thumb|right|225px|An array of 17 purpose-built oxygen-depleted titanium dioxide memristors built at HP Labs, imaged by an atomic force microscope. The wires are about 50 nm, or 150 atoms, wide. Electric current through the memristors shifts the oxygen vacancies, causing a gradual and persistent change in electrical resistance.

Memristor (; a portmanteau of "memory resistor") is a name of passive two-terminal circuit element in which there is a functional relationship between charge and magnetic flux linkage. Memristor theory was formulated and named by Leon Chua in a 1971 paper. In 2008, a team at HP Labs announced the development of a switching memristor based on a thin film of titanium dioxide. It has a regime of operation with an approximately linear charge-resistance relationship as long as the time-integral of the current stays within certain bounds. These devices are being developed for application in nanoelectronic memories, computer logic, and neuromorphic computer architectures.

Background

A memristor is a passive two-terminal electronic component in which there is a functional relationship between charge and magnetic flux linkage. When current flows in one direction through the device, the resistance increases; and when current flows in the opposite direction, the resistance decreases. When the current is stopped, the component retains the last resistance that it had, and when the flow of charge starts again, the resistance of the circuit will be what it was when it was last active.

More generally, a memristor is a two-terminal component in which the resistance depends on the integral of the input applied to the terminals (rather than on the instantaneous value of the input as in a varistor). Since the element "remembers" the amount of current that has passed through it in the past, it was tagged by Chua with the name "memristor." Another way of describing a memristor is that it is any passive two-terminal circuit elements that maintains a functional relationship between the time integral of current (called charge) and the time integral of voltage (often called flux, as it is related to magnetic flux). The slope of this function is called the memristance ''M'' and is similar to variable resistance. Batteries can be considered to have memristance, but they are not passive devices. The definition of the memristor is based solely on the fundamental circuit variables of current and voltage and their time-integrals, just like the resistor, capacitor, and inductor. Unlike those three elements however, which are allowed in linear time-invariant or LTI system theory, memristors of interest have a nonlinear function and may be described by any of a variety of functions of net charge. There is no such thing as a standard memristor. Instead, each device implements a particular function, wherein the integral of voltage determines the integral of current, and vice versa. A linear time-invariant memristor is simply a conventional resistor.

In his 1971 paper, memristor theory was formulated and named by Leon Chua, extrapolating the conceptual symmetry between the resistor, inductor, and capacitor, and inferring the memristor was a similarly fundamental device. (However, as mentioned above, if it has no non-linearity then it is the same as a standard resistor. It is more meaningful to compare it with a varistor, which has a non-linear relationship between current and voltage.) Other scientists had already proposed fixed nonlinear flux-charge relationships, but Chua's theory introduced generality.

Like other two-terminal components (''e.g.,'' resistor, capacitor, inductor), real-world devices are never purely memristors ("ideal memristor"), but will also exhibit some amount of capacitance, resistance, and inductance. Note however that a "memristor" with constant ''M'' and a resistor with constant ''R'' (i.e. not a varistor) are the same thing.

Theory

The memristor is essentially a two-terminal variable resistor, with resistance dependent upon the amount of charge ''q'' that has passed between the terminals.

:$V\; =\; I\; \backslash cdot\; M(q)$

To relate the memristor to the resistor, capacitor, and inductor, it is helpful to isolate the term ''M''(''q''), which characterizes the device, and write it as a differential equation:

M = dΦ_m / dQ,

where Q is defined by I = dQ/dt, and Φ_m is defined by V = dΦ_m/dt. Note that the above table covers all meaningful ratios of ''I'', ''Q'', ''Φ''_m, and ''V''. No device can relate ''I'' to ''Q'', or ''Φ''_m to ''V'', because ''I'' is the derivative of ''Q'' and ''Φ''_m is the integral of ''V''.

The variable ''Φ''_m ("magnetic flux linkage") is generalized from the circuit characteristic of an inductor. It ''does not'' represent a magnetic field here, and its physical meaning is discussed below. The symbol ''Φ''_m may simply be regarded as the integral of voltage over time.

Thus, the memristor is formally defined as a two-terminal element in which the flux linkage (or integral of voltage) Φ_m between the terminals is a function of the amount of electric charge ''Q'' that has passed through the device. Each memristor is characterized by its memristance function describing the charge-dependent rate of change of flux with charge.

:$M(q)=\backslash frac\{\backslash mathrm\; d\backslash Phi\_m\}\{\backslash mathrm\; dq\}$

Substituting that the flux is simply the time integral of the voltage, and charge is the time integral of current, we may write the more convenient form

:$M(q(t))=\backslash cfrac\{\backslash mathrm\; d\backslash Phi\_m/\backslash mathrm\; dt\}\{\backslash mathrm\; dq/\backslash mathrm\; dt\}=\backslash frac\{V(t)\}\{I(t)\}$

It can be inferred from this that memristance is simply charge-dependent resistance. If ''M''(''q(t)'') is a constant, then we obtain Ohm's Law ''R(t)'' = ''V(t)''/'' I(t)''. If ''M''(''q(t)'') is nontrivial, however, the equation is not equivalent because ''q(t)'' and ''M''(''q(t)'') will vary with time. Solving for voltage as a function of time we obtain

:$V(t)\; =\backslash \; M(q(t))\; I(t)$

This equation reveals that memristance defines a linear relationship between current and voltage, as long as ''M'' does not vary with charge. Of course, nonzero current implies time varying charge. Alternating current, however, may reveal the linear dependence in circuit operation by inducing a measurable voltage without net charge movement—as long as the maximum change in ''q'' does not cause much change in ''M''.

Furthermore, the memristor is static if no current is applied. If ''I''(''t'') = 0, we find ''V''(''t'') = 0 and ''M''(''t'') is constant. This is the essence of the memory effect.

The power consumption characteristic recalls that of a resistor, ''I''²''R''.

:$P(t)\; =\backslash \; I(t)V(t)\; =\backslash \; I^2(t)\; M(q(t))$

As long as ''M''(''q''(''t'')) varies little, such as under alternating current, the memristor will appear as a constant resistor. If ''M''(''q''(''t'')) increases rapidly, however, current and power consumption will quickly stop.

Derivation of "flux linkage" in a passive device

In an inductor, magnetic flux Φ_m relates to Faraday's law of induction, which states that the energy to push charges around a loop (electromotive force, in units of Volts) equals the negative derivative of the flux through the loop:

:$\backslash mathcal\; E\; =\; -\backslash frac\{\backslash mathrm\; d\backslash Phi\_\backslash mathrm\; m\}\{\backslash mathrm\; dt\}$

This notion may be extended by analogy to a single device. Working against an accelerating force (which may be EMF, or any applied voltage), a resistor produces a decelerating force, and an associated "flux linkage" varying with opposite sign. For example, a high-valued resistor will quickly produce flux linkage. The term "flux linkage" is generalized from the equation for inductors, where it represents a physical magnetic flux: If 1 Volt is applied across an inductor for 1 second, then there is 1 V·s of flux linkage in the inductor, which represents energy stored in a magnetic field that may later be obtained from it. The same voltage over the same time across a resistor results in the same flux linkage (as defined here, in units of V·s), but the energy is dissipated, rather than stored in a magnetic field — there is no physical magnetic field involved as a link to anything. Voltage for passive devices is evaluated in terms of energy ''lost'' by a unit of charge, so generalizing the above equation simply requires reversing the sense of EMF.

:$V\; =\; \backslash frac\{\backslash mathrm\; d\backslash Phi\_\backslash mathrm\; m\}\{\backslash mathrm\; dt\backslash ,\}$

:$\backslash Phi\_\backslash mathrm\; m\; =\; \backslash int\; V\backslash mathrm\; dt$

Observing that Φ_m is simply equal to the integral over time of the potential drop between two points, we find that it may readily be calculated, for example by an operational amplifier configured as an integrator.

Two unintuitive concepts are at play:

Magnetic flux is defined here as generated by a resistance in opposition to an applied field or electromotive force. In the absence of resistance, flux due to constant EMF, and the magnetic field within the circuit, would increase indefinitely. The opposing flux induced in a resistor must also increase indefinitely so the sum with applied EMF remains finite.

Any appropriate response to applied voltage may be called "magnetic flux," as the term is used here.

The upshot is that a passive element may relate some variable to flux without storing a magnetic field. Indeed, a memristor always appears instantaneously as a resistor. As shown above, assuming non-negative resistance, at any instant it is dissipating power from an applied EMF and thus has no outlet to dissipate a stored field into the circuit. This contrasts with an inductor, for which a magnetic field stores all energy originating in the potential across its terminals, later releasing it as an electromotive force within the circuit.

Physical restrictions on ''M''(''q'')

''M''(''q'') is physically restricted to be positive for all values of ''q'' (assuming the device is passive and does not become superconductive at some ''q''). A negative value would mean that it would perpetually supply energy when operated with alternating current.

An applied constant voltage potential results in uniformly increasing Φ_m. It is not realistic for the function ''M''(''q'') to contain an infinite amount of information over this infinite range. Three alternatives avoid this physical impossibility:

''M''(''q'') approaches zero, such that Φ_m = �?�''M''(''q'')d''q'' = �?�''M''(''q''(''t''))''I''(''t'') d''t'' remains bounded, but continues changing at an ever-decreasing rate. Eventually, this would encounter some kind of quantization and non-ideal behavior.

''M''(''q'') is periodic, so that ''M''(''q'') = ''M''(''q'' − Δ''q'') for all ''q'' and some Δ''q'', e.g. sin²(''q''/''Q'').

The device enters hysteresis once a certain amount of charge has passed through, or otherwise ceases to act as a memristor.

Memristive systems

The memristor was generalized to memristive systems in a 1976 paper by Leon Chua. Whereas a memristor has mathematically scalar state, a system has vector state. The number of state variables is independent of, and usually greater than, the number of terminals.

In this paper, Chua applied this model to empirically observed phenomena, including the Hodgkin-Huxley model of the axon and a thermistor at constant ambient temperature. He also described memristive systems in terms of energy storage and easily observed electrical characteristics. These characteristics match resistive random-access memory and phase-change memory, relating the theory to active areas of research.

In the more general concept of an ''n''-th order memristive system the defining equations are

:$V(t)=M(\backslash textbf\{w\},I,t)I(t),$ :$\backslash dot\{\backslash textbf\{w\}\}=f(\backslash textbf\{w\},I,t)$

where the vector w represents a set of ''n'' state variables describing the device. The ''pure'' memristor is a particular case of these equations, namely when ''M'' depends only on charge (w=''q'') and since the charge is related to the current via the time derivative d''q''/d''t''=''I''. For ''pure'' memristors ''f'' is not an explicit function of ''I''.

Operation as a switch

For some memristors, applied current or voltage will cause a great change in resistance. Such devices may be characterized as switches by investigating the time and energy that must be spent in order to achieve a desired change in resistance. Here we will assume that the applied voltage remains constant and solve for the energy dissipation during a single switching event. For a memristor to switch from ''R''_on to ''R''_off in time ''T''_on to ''T''_off, the charge must change by ΔQ = ''Q''_on−''Q''_off.

:$E\_\{\backslash mathrm\{switch\}\}\; =\backslash \; V^2\backslash int\_\{T\_\backslash mathrm\{off\}\}^\{T\_\backslash mathrm\{on\}\}\; \backslash frac\{\backslash mathrm\; dt\}\{M(q(t))\}\; =\backslash \; V^2\backslash int\_\{Q\_\backslash mathrm\{off\}\}^\{Q\_\backslash mathrm\{on\}\}\backslash frac\{\backslash mathrm\; dq\}\{I(q)M(q)\}\; =\backslash \; V^2\backslash int\_\{Q\_\backslash mathrm\{off\}\}^\{Q\_\backslash mathrm\{on\}\}\backslash frac\{\backslash mathrm\; dq\}\{V(q)\}\; =\backslash \; V\backslash Delta\; Q$

To arrive at the final expression, substitute ''V''=''I''(''q'')''M''(''q''), and then �?�d''q''/''V'' = �?�''Q''/''V'' for constant ''V''. This power characteristic differs fundamentally from that of a metal oxide semiconductor transistor, which is a capacitor-based device. Unlike the transistor, the final state of the memristor in terms of charge does not depend on bias voltage.

The type of memristor described by Williams ceases to be ideal after switching over its entire resistance range and enters hysteresis, also called the "hard-switching regime." Another kind of switch would have a cyclic ''M''(''q'') so that each ''off''-''on'' event would be followed by an ''on''-''off'' event under constant bias. Such a device would act as a memristor under all conditions, but would be less practical.

Implementations

Titanium dioxide memristor

Interest in the memristor revived when an experimental solid state version was reported by R. Stanley Williams of Hewlett Packard. The article was the first to demonstrate that a solid-state device could have the characteristics of a memristor based on the behavior of nanoscale thin films. The device neither uses magnetic flux as the theoretical memristor suggested, nor stores charge as a capacitor does, but instead achieves a resistance dependent on the history of current.

Although not cited in HP's initial reports on their TiO₂ memristor, the resistance switching characteristics of titanium dioxide was originally described in the 1960s.

The HP device is composed of a thin (50 nm) titanium dioxide film between two 5 nm thick electrodes, one Ti, the other Pt. Initially, there are two layers to the titanium dioxide film, one of which has a slight depletion of oxygen atoms. The oxygen vacancies act as charge carriers, meaning that the depleted layer has a much lower resistance than the non-depleted layer. When an electric field is applied, the oxygen vacancies drift (see ''Fast ion conductor''), changing the boundary between the high-resistance and low-resistance layers. Thus the resistance of the film as a whole is dependent on how much charge has been passed through it in a particular direction, which is reversible by changing the direction of current. Since the HP device displays fast ion conduction at nanoscale, it is considered as a nanoionic device.

Memristance is displayed only when both the doped layer and depleted layer contribute to resistance. When enough charge has passed through the memristor that the ions can no longer move, the device enters hysteresis. It ceases to integrate ''q''=�?�''I''d''t'', but rather keeps ''q'' at an upper bound and ''M'' fixed, thus acting as a constant resistor until current is reversed.

Memory applications of thin-film oxides had been an area of active investigation for some time. IBM published an article in 2000 regarding structures similar to that described by Williams. Samsung has a U.S. patent for oxide-vacancy based switches similar to that described by Williams. Williams also has a pending U.S. patent application related to the memristor construction.

Although the HP memristor is a major discovery for electrical engineering theory, it has yet to be demonstrated in operation at practical speeds and densities. Graphs in Williams' original report show switching operation at only ~1 Hz. Although the small dimensions of the device seem to imply fast operation, the charge carriers move very slowly, with an ion mobility of 10⁻¹⁰ cm²/(Vs). In comparison, the highest known drift ionic mobilities occur in advanced superionic conductors, such as rubidium silver iodide with about 2×10⁻⁴ cm²/(Vs) conducting silver ions at room temperature. Electrons and holes in silicon have a mobility ~1000 cm²/(Vs), a figure which is essential to the performance of transistors. However, a relatively low bias of 1 volt was used, and the plots appear to be generated by a mathematical model rather than a laboratory experiment.

In April 2010, HP labs announced that they had practical memristors working at 1 ns (~1 GHz) switching times and 3 nm by 3 nm sizes, with electron/hole mobility of 1 m/s, which bodes well for the future of the technology. At these densities it could easily rival the current sub-25 nm flash memory technology.

Polymeric memristor

In July 2008, Victor Erokhin and Marco P. Fontana, in ''Electrochemically controlled polymeric device: a memristor (and more) found two years ago'', claim to have developed a polymeric memristor before the titanium dioxide memristor more recently announced.

In 2004, Juri H. Krieger and Stuart M. Spitzer published a paper "Non-traditional, Non-volatile Memory Based on Switching and Retention Phenomena in Polymeric Thin Films" at the IEEE Non-Volatile Memory Technology Symposium, describing the process of dynamic doping of polymer and inorganic dielectric-like materials in order to improve the switching characteristics and retention required to create functioning nonvolatile memory cells. Described is the use of a special passive layer between electrode and active thin films, which enhances the extraction of ions from the electrode. It is possible to use fast ion conductor as this passive layer, which allows to significantly decrease the ionic extraction field.

Spin memristive systems

Spintronic Memristor

Yiran Chen and Xiaobin Wang, researchers at disk-drive manufacturer Seagate Technology, in Bloomington, Minnesota, described three examples of possible magnetic memristors in March, 2009 in IEEE Electron Device Letters. In one of the three, resistance is caused by the spin of electrons in one section of the device pointing in a different direction than those in another section, creating a "domain wall," a boundary between the two states. Electrons flowing into the device have a certain spin, which alters the magnetization state of the device. Changing the magnetization, in turn, moves the domain wall and changes the device's resistance.

This work attracted significant attention from the electronics press, including an interview by IEEE Spectrum.

Spin Torque Transfer Magnetoresistance

Spin Torque Transfer MRAM is a well-known device that exhibits memristive behavior. The resistance is dependent on the relative spin orientation between two sides of a magnetic tunnel junction. This in turn can be controlled by the spin torque induced by the current flowing through the junction. However, the length of time the current flows through the junction determines the amount of current needed, i.e., the charge flowing through is the key variable.Additionally, as reported by Krzysteczko et al., MgO based magnetic tunnel junctions show memristive behavior based on the drift of oxygen vacancies within the insulating MgO layer (resistive switching). Therefore, the combination of spin transfer torque and resistive switching leads naturally to a second-order memristive system with w=(''w₁'',''w₂'') where ''w₁'' describes the magnetic state of the magnetic tunnel junction and ''w₂'' denotes the resistive state of the MgO barrier. Note that in this case the change of ''w₁'' is current-controlled (spin torque is due to a high current density) whereas the change of ''w₂'' is voltage-controlled (the drift of oxygen vacancies is due to high electric fields).

Spin Memrisitive System

A fundamentally different mechanism for memristive behavior has been proposed by Yuriy V. Pershin and Massimiliano Di Ventra in their paper "Spin memristive systems". The authors show that certain types of semiconductor spintronic structures belong to a broad class of memristive systems as defined by Chua and Kang. The mechanism of memristive behavior in such structures is based entirely on the electron spin degree of freedom which allows for a more convenient control than the ionic transport in nanostructures. When an external control parameter (such as voltage) is changed, the adjustment of electron spin polarization is delayed because of the diffusion and relaxation processes causing a hysteresis-type behavior. This result was anticipated in the study of spin extraction at semiconductor/ferromagnet interfaces, but was not described in terms of memristive behavior. On a short time scale, these structures behave almost as an ideal memristor. This result broadens the possible range of applications of semiconductor spintronics and makes a step forward in future practical applications of the concept of memristive systems.

Manganite memristive systems

Although not described using the word "memristor", a study was done of bilayer oxide films based on manganite for non-volatile memory by researchers at the University of Houston in 2001. Some of the graphs indicate a tunable resistance based on the number of applied voltage pulses similar to the effects found in the titanium dioxide memristor materials described in the Nature paper "The missing memristor found".

Resonant tunneling diode memristor

In 1994, F. A. Buot and A. K. Rajagopal of the U.S. Naval Research Laboratory demonstrated that a 'bow-tie' current-voltage (I-V) characteristics occurs in AlAs/GaAs/AlAs quantum-well diodes containing special doping design of the spacer layers in the source and drain regions, in agreement with the published experimental results. This 'bow-tie' current-voltage (I-V) characteristic is characteristic of a memristor although the term memristor was not explicitly used in their papers. No magnetic interaction is involved in the analysis of the 'bow-tie' I-V characteristics.

Potential applications

Williams' solid-state memristors can be combined into devices called crossbar latches, which could replace transistors in future computers, taking up a much smaller area.

They can also be fashioned into non-volatile solid-state memory, which would allow greater data density than hard drives with access times potentially similar to DRAM, replacing both components. HP prototyped a crossbar latch memory using the devices that can fit 100 gigabits in a square centimeter, and has designed a highly scalable 3D design (consisting of up to 1000 layers or 1 petabit per cm³). HP has reported that its version of the memristor is currently about one-tenth the speed of DRAM. The devices' resistance would be read with alternating current so that the stored value would not be affected.

Some patents related to memristors appear to include applications in programmable logic, signal processing, neural networks, and control systems.

Recently, a simple electronic circuit consisting of an LC network and a memristor was used to model experiments on adaptive behavior of unicellular organisms. It was shown that the electronic circuit subjected to a train of periodic pulses learns and anticipates the next pulse to come, similarly to the behavior of slime molds ''Physarum polycephalum'' where the viscosity of channels in the cytoplasm respond to periodic changes of environment. Such a learning circuit may find applications, e.g., in pattern recognition. The DARPA’s SyNAPSE project has funded HP Labs, in collaboration with the Boston University Neuromorphics Lab, to develop neuromorphic architectures which may be based on memristive systems. In 2010, Massimiliano Versace and Ben Chandler co-wrote an article describing the MoNETA (Modular Neural Exploring Traveling Agent) model. MoNETA is the first large-scale neural network model to implement whole-brain circuits to power a virtual and robotic agent compatibly with memristive hardware computations. The software used to implement MoNETA, Cog Ex Machina, has been featured on the cover page of IEEE Computer in February 2011 in a joint article by HP Labs and the Boston University Neuromorphics Lab. The same lab has show in 2011 how memristors could be coupled with fuzzy logic to manufacture chips able to implement neural computation with a low power budget.

Memcapacitors and meminductors

In 2009, Massimiliano Di Ventra, Yuriy Pershin and Leon Chua co-wrote an article extending the notion of memristive systems to capacitive and inductive elements in the form of memcapacitors and meminductors whose properties depend on the state and history of the system.

Historical timeline

;1960 : Bernard Widrow develops a 3-terminal device called a "memistor" as a new fundamental circuit component forming the basis of a neural network circuit called ADALINE (ADAptive LInear NEuron).

;1967 : J.G. Simmons and R.R. Verderber publish an article in the ''Proceeding of the Royal Society of London'' entitled "New conduction and reversible memory phenomena in thin insulating films". The article notes hysteretic resistance switching effects in thin film (20-300 nm) silicon oxide having injected gold ions. Electron trapping is suggested as the explanation for the phenomena.

;1968 : F. Argall publishes an article in ''Solid-State Electronics'' entitled "Switching Phenomena in Titanium Oxide Thin Films". Although the article is not cited in HP's memristor papers the article describes substantially similar experimental data.

;1969 : G. Dearnaley A. M. Stoneham and D.V. Morgan 1969 J. Non Cryst. Sol. 4, 593 612 suggest the filamentary model for switching. They showed there were no injected gold ions in the silicon oxide films. Their 1970 paper G. Dearnaley A. M. Stoneham and D.V. Morgan 1970 Rep. Prog. Phys. 33, 1129 1191 reviewed and compared the several mechanisms proposed. This paper was translated into Russian as Uspekhi Fizicheskikh Nauk 112 83 128 (1974).

;1971 : Leon Chua, a professor at UC Berkeley, postulates a new two-terminal circuit element characterized by a relationship between charge and flux linkage as a fourth fundamental circuit element in the article "Memristor-the Missing Circuit Element" published in IEEE Transactions on Circuit Theory.

;1976 : Leon Chua and his student Sung Mo Kang publish a paper entitled "Memristive Devices and Systems" in the ''Proceedings of the IEEE'' generalizing the theory of memristors and memristive systems including a property of zero crossing in the Lissajous curve characterizing current vs. voltage behavior.

;1986 : Robert Johnson and Stanford Ovshinsky receive U.S. Patent 4,597,162 describing manufacturing of a 2-terminal reconfigurable resistance switching array based on phase changing materials. While distinct from memristor behavior, some of the basic elements later used by Stan Williams group such as the use of a crossbar architecture and the basic use of a 2-terminal resistance switch are found in this patent.

;1990 : S.Thakoor, A. Moopenn, T. Daud, and A.P. Thakoor publish an article entitled "Solid-state thin-film memistor for electronic neural networks" in the ''Journal of Applied Physics''. The article teaches a tungsten oxide electrically reprogrammable variable resistance device, but it is unclear whether the "memistor" referred to in the title has any connection to the memristor of Chua. In addition, the cited references of this article do not include any of Chua's publications on the memristor so this appears to be a coincidence.

;1992 : (August 27) Juri H. Krieger and Nikolai F. Yudanov receive RU. Patent 2,071,126 in the first describing application of a super-ionic material with high ion mobility for creating a resistance switching memory cell.

;1993 : (November 3) Ju. H. Krieger, N.F. Yudanov, I.K. Igumenov and S.B. Vaschenko publish an article entitled "Study of Test Structures of a Molecular Memory Element" The article describe manufacturing of a resistance switching memory cell based on a conjugated polymer.

: Katsuhiro Nichogi, Akira Taomoto, Shiro Asakawa, Kunio Yoshida of the Matsushita Research Institute receive U.S. Patent 5,223,750 describing an artificial neural function circuit formed using two-terminal organic thin film resistance switches which appear to have some properties similar to the memristor. However, no specific mention of memristors is made.

;1994 : F. A. Buot and A. K. Rajagopal publish in the ''Journal of Applied Physics'' an article entitled "Binary information storage at zero bias in quantum-well diodes". The article demonstrates the existence of a memristor-'bow-tie' current-voltage characteristics in AlAs/GaAs/AlAs quantum-well diodes with special spacer-layer doping design. The analysis does not involve magnetic interaction and the authors were not aware of Chua's publications on memristor. It appears that the analysis bears no direct connection to the memristor of Chua.

;1998 : (June 2) Michael Kozicki and William West receive U.S. Patent 5,761,115 (assigned to Axon Technologies Corp. and the Arizona Board of Regents) describing the Programmable metallization cell, a device which consists of an ion conductor between two or more electrodes and whose resistance or capacitance can be programmed via the growth and dissolution of a metal "dendrite". No connection to memristors is made, but the functionality is similar.

: (June 3) Bhagwat Swaroop, William West, Gregory Martinez, Michael Kozicki, and Lex Akers publish a paper entitled "Programmable Current Mode Hebbian Learning Neural Network Using Programmable Metallization Cell" in the ''Proceedings of the IEEE International Symposium on Circuits and Systems'', demonstrating that the complexity of an artificial synapse can be minimized by using an ionic programmable resistance device.

: (June 12) James R. Heath, Philip Kuekes, Gregory Snider, and Stan Williams, of HP Labs, publish a paper in ''Science'' entitled "A Defect-Tolerant Computer Architecture: Opportunities for Nanotechnology". The article discusses how the possibility of a chemically fabricated 2-terminal configurable bit element can be implemented in a crossbar configuration and provide for defect tolerant computing. No connection to memristors is yet identified.

: (November 12) Ju. H. Krieger, N.F. Yudanov, I.K. Igumenov and S.B. Vaschenko publish an article entitled "Molecular Analogue Memory Cell" in the ''Proceedings of the Sixth Foresight Conference on Molecular Nanotechnology'', Santa Clara, California.

;2000 : (July 3) A. Beck, J. G. Bednorz, Ch. Gerber, C. Rossel, and D. Widmer of IBM's Zurich Research Laboratory describe reproducible resistance switching effects in thin oxide films in the article "Reproducible switching effect in thin oxide films for memory applications" published in ''Applied Physics Letters''. The switches are noted as having hysteretic features similar to memristors, but no connection to memristors is yet noted.

: (October 3) Philip Kuekes, Stanley Williams, and James Heath, of HP Labs, receive U.S. Patent 6,128,214 (assigned to Hewlett-Packard) describing a nanoscale crossbar using a rotaxane molecular structure as a 2-terminal non-linear resistance switch. The connection to the memristor theory is not yet recognized.

;2001 : Shangqing Liu, NaiJuan Wu, Xin Chen, and Alex Ignatiev, researchers in the Space Vacuum Epitaxy Center of the University of Houston, present results during a non-volatile memory conference held in San Diego, California on November 6–7 in the article "A New Concept for Non-Volatile Memory: The Electric Pulse Induced Resistive Change Effect in Colossal Magnetoresistive Thin Films". This appears to be the first identification of the importance of oxide bilayers to achieve a high to low resistance ratio. Data is provided indicative of the zero-crossing Lissajous curves discussed by Chua and Kang, but no connection to memristors is yet noted and no explanation for the underlying mechanism is provided.

: (May 1) Ju. H. Krieger, S.V. Trubin S.B., Vaschenko and N.F. Yudanov publish an article entitled "Molecular analogue memory cell based on electrical switching and memory in molecular thin films" The article describe manufacturing of a two-terminal resistance switching array (8x8) based on a soluble oligomers of a conjugated polymer and an ionic complex (sodium salt). This principle allows creating memory cells with several bits per one cell and will allow working out the artificial neuron for neural networks and neural computers.

: (August 13) Ju. H. Krieger and N.F. Yudanov have a pending PCT International Application PCT/RU01/00334 describing memory cells having active and passive layers may store multiple information bits. The active layer may include conjugated polymers, an inclusion compounds or different type of oxide that have a variable resistance based on the movement of ions and electrons between the passive layer and the active layer. The passive layer may be a super-ionic material that has high ion and electron mobility.

;2003 : A. Bandyopadhyay and A. J. Pal from Indian Association for the Cultivation of Science demonstrated Large conductance switching and memory effects in organic molecules for data-storage applications, in Appl. Phys. Lett. 82, 1215 (2003). They demonstrated current-voltage characteristics similar to the prediction of Chua's memristor and they demonstrated Random Access Memory for millions of times and Read Only memory for hours. They tuned the memristive property using functional groups, A. Bandyopadhyay and A. J. Pal, J. Phys. Chem. B. 107, 2531 (2003). They tuned memristive features via Self-assembled Supramolecular Structures, A. Bandyopadhyay, A. J. Pal, Adv. Mater. 15, 1949 (2003).

;2004 : Ju. H. Krieger and N.F. Yudanov receive U.S. Patent 6,768,157 (July 27), 6,806,526 (October 19) 6,815,286 (November 9) (assigned to Advanced Micro Devices) describing memory cells having active and passive layers may store multiple information bits. The active layer may include conjugated polymers, an inclusion compounds or different type of oxide that have a variable resistance based on the movement of ions and electrons between the passive layer and the active layer. The passive layer may be a super-ionic material that has high ion and electron mobility.

: (15–17 November) Ju. H. Krieger and Stuart M. Spitzer publish a paper in the ''IEEE Proceeding 2004 Non-Volatile Memory Technology Symposium'' entitled "Non-volatile Memory Based on Switching and Retention Phenomena in Polymeric Thin Films". This work describes the process of dynamic doping of polymer and inorganic dielectric-like materials in order to improve the switching characteristics and retention required to create functioning nonvolatile memory cells.

;2005 : (March 22) Darrell Rinerson, Christophe Chevallier, Steven Longcor, Wayne Kinney, Edmond Ward, and Steve Kuo-Ren Hsia receive U.S. Patent 6,870,755 (assigned to Unity Semiconductor) including basic patent claims to reversible 2-terminal resistance switching materials based on metal oxides.

: Ju. H. Krieger and N.F. Yudanov receive U.S. Patent 6,838,720 (January 4) 6,855,977 (February 15), 6,858,481 (February 22), 6,864,522 (March 8), 6,873,540 (March 29) (assigned to Advanced Micro Devices) describing manufacturing of a two-terminal resistance switching memory cells having active and passive layers. Employing self-assembly produces polymer memory cells at the precise locations of the contacts of the transistor array. The mechanism of inducing the conductivity change of the polymer by changing its doping concentration provides a promising approach to make various memory devices.

: (November 1) Zhida Lan, Colin Bill, and Michael A. VanBuskirk receive U.S. Patent 6,960,783 (assigned to Advanced Micro Devices) teaching a resistance switching memory cell formed from a layer of organic material and a layer of metal oxides or sulfides. The I-V characteristic is similar to the memristor, but no mention of the memristor is included in the description.

;2006 : (February 14) Stanford Ovshinsky receives U.S. Patent 6,999,953 describing a neural synaptic system based on phase change material used as a 2-terminal resistance switch. Leon Chua's original memristor paper is cited by the U.S. Patent Office as a pertinent prior art reference, but no specific reference of connection to the memristor theory is made.

: Ju. H. Krieger and N.F. Yudanov receive U.S. Patents 6,992,323 (January 31), 7,026,702 (April 11), 7,113,420 (September 26) (assigned to Advanced Micro Devices) describing manufacturing of a two-terminal resistance switching memory cells.

: (September 11) Shangquig Liu, Naijuan Wu, Alex Ignatiev, and Jianren Li publish an article entitled "Electric-pulse-induced capacitance change effect in perovskite oxide thin films" which appears to disclose effects similar to that of a memcapacitor.

;2007 : (January 2) Juri H. Krieger and Stuart M. Spitzer receive U.S. Patent 7,157,732 (assigned to Spansion) describing manufacturing of a switchable diode with memory having a passive and active layer with asymmetric semiconducting properties. The active layer may include conjugated polymers, an inclusion compounds or different type of oxide that have a variable resistance based on the movement of ions and electrons between the passive layer and the active layer. The passive layer may be a super-ionic material that has high ion and electron mobility.

: (February 27) Vladimir Bulovic, Aaron Mandell, and Andrew Perlman, receive U.S. Patent 7,183,141 (assigned to Spansion), including basic claims to methods of programming 2-terminal ionic complex resistance switches to act as a fuse or anti-fuse.

: (April 10) Gregory Snider of HP Labs receives U.S. Patent 7,203,789, assigned to Hewlett-Packard, describing implementations of 2-terminal resistance switches similar to memristors in reconfigurable computing architectures.

: (August 10) Gregory Snider of HP Labs publishes the article "Self-organized computation with unreliable, memristive nanodevices" in the ''Journal of Nanoscience and Nanotechnology'' discussing memristive nanodevices useful to pattern recognition and reconfigurable circuit architectures.

: (November 27) Blaise Mouttet, a graduate student at George Mason University, receives U.S. Patent 7,302,513 describing uses for 2-terminal resistance switching materials in signal processing, control systems, communications, and pattern recognition.

;2008 : (April 15) Greg Snider of HP Labs receives U.S. Patent 7,359,888 (assigned to Hewlett-Packard) including basic claims to a nanoscale 2-terminal resistance switch crossbar array formed as a neural network.

: (May 1) Dmitri Strukov, Gregory Snider, Duncan Stewart, and Stan Williams, of HP Labs, publish an article in Nature "The missing memristor found" identifying a link between the 2-terminal resistance switching behavior found in nanoscale systems and Leon Chua's memristor.

: (June 1–5) Blaise Mouttet, a graduate student at George Mason University, presents a poster entitled "Logicless Computational Architectures with Nanoscale Crossbar Arrays" describing analog computational architectures using 2-terminal resistance switching materials similar to the memristor at the 2008 NSTI Nanotechnology Conference and Trade Show in Boston.

: (July 7) Victor Erokhin and M.P. Fontana claim to have developed a polymeric memristor before the titanium dioxide memristor of Stan Williams group in the article "Electrochemically controlled polymeric device: a memristor (and more) found two years ago".

: (July 15) J. Joshua Yang, Matthew D. Pickett, Xuema Li, Douglas A. A. Ohlberg, Duncan R. Stewart and R. Stanley Williams publish an article in ''Nature Nanotechnology'' "Memristive switching mechanism for metal/oxide/metal nano-devices" demonstrating the memristive switching behavior and mechanism in nanodevices.

: (August 26) Stefanovich Genrikh, Choong-rae Cho, In-kyeong Yoo, Eun-hong Lee, Sung-il Cho, and Chang-wook Moon, receive U.S. Patent 7,417,271 (assigned to Samsung) including basic patent claims to a bilayer oxide 2-terminal resistance switch having memristive properties. However, the connection to Leon Chua's theory is not recognized in the patent description.

: (September 14–16) Blaise Mouttet, a graduate student at George Mason University, presents a poster entitled "Proposal for Memristors in Signal Processing" at Nano-Net 2008, a nanotechnology conference in Boston.

: (September 23) Yu V. Pershin and M. Di Ventra of University of California, San Diego publish an article in ''Physical Review Letters'' entitled "Spin memristive systems: Spin memory effects in semiconductor spintronics" which notes memristive behavior in spintronics.

: (October 22) Yu V. Pershin, S. La Fontaine, M. Di Ventra publish an article entitled "Memristive model of amoeba's learning" identifying memristive behavior in amoeba's learning.

: (October 28) Duncan Stewart, Patricia Beck, and Doug Ohlberg, researchers at HP Labs, receive U.S. Patent 7,443,711 (assigned to Hewlett-Packard) including basic patent claims to a tunable nanoscale 2-terminal resistance switch.

: (November 4) Blaise Mouttet, a graduate student at George Mason University, receives U.S. Patent 7,447,828 including various patent claims to using 2-terminal resistance switching materials in adaptive signal processing.

: (November 21) Leon Chua, Stan Williams, Greg Snider, Rainer Waser, Wolfgang Porod, Massimiliano Di Ventra, and Blaise Mouttet speak at a Symposium on Memristors and Memristive Systems held at University of California, Berkeley. Discussion includes the theoretical foundations of memristors and memristive systems of Leon Chua and Sung Mo Kang and the prospects of memristors for RRAM and neuromorphic electronic architectures.

: (December 2) Blaise Mouttet receives U.S. Patent 7,459,933 including various patent claims to using 2-terminal hysteretic resistance materials for image processing and pattern recognition.

;2009 : (January 21) Sung Hyun Jo, Kuk-Hwan Kim, and Wei Lu of the University of Michigan publish an article in ''NanoLetters'' entitled "High-Density Crossbar Arrays Based on a Si Memristive System", which details an amorphous silicon based memristive material capable of being integrated with CMOS devices.

: (January 23) Massimiliano Di Ventra, Yuriy V. Pershin, Leon O. Chua submit an article in arXiv entitled "Circuit elements with memory: memristors, memcapacitors and meminductors". which extends the notion of memristive systems to capacitive and inductive elements, namely capacitors and inductors whose properties depend on the state and history of the system.

: (January 30) Blaise Mouttet published a Google knol article entitled: "An Introduction to Memimpedance and Memadmittance Systems Analysis", which is an explanation on "Circuit elements with memory: memristors, memcapacitors and meminductors" and Chua's memristor paper.

: (February 10) HP Labs group publish an article entitled "A hybrid nanomemristor/transistor logic circuit capable of self-programming" in the ''Proceedings of the National Academy of Sciences''.

: (May 1) An article is published in NanoLetters entitled "Nanoparticle Assemblies as Memristors" describing a newly discovered memristor material based on magnetite nanoparticles and proposing an extended memristor model including both time-dependent resistance and time-dependent capacitance.

: (May 19) Yuriy Pershin and Massimiliano Di Ventra published a preliminary article in ''Nature Precedings'' entitled "Experimental demonstration of associative memory with memristive neural networks" in which a memristor emulator demonstrates properties of a neural synapse.

: (June 2) A. Delgado published a paper entitled "Input Output Linearization of Memristive Systems" in the ''Proceedings of the 2009 IEEE Nanotechnology Materials and Devices Conference''; this work demonstrates that feedback linearization can be applied to the memristor producing a linear device.

: (June 3) Scientists at NIST published an article in IEEE Electron Device Letters entitled "A Flexible Solution-Processed Memristor". NIST's memristor is based on TiO2 like HPLabs, but is fabricated using a less expensive room temperature deposition process and deposits the memristive material on flexible polymer sheets with potential applications as components of biosensors or radio-frequency identification (RFID).

: (July 13) At the 2nd International Multi-Conference on Engineering and Technological Innovation, Blaise Mouttet of George Mason University described a memristor-based pattern recognition circuit performing an analog variation of the exclusive nor function. The circuit architecture is proposed as a way to circumvent Von Neumann's bottleneck for processors used in robotic control systems.

: (August 4) The physical realization of an electrically modifiable array of memristive neural synapses is achieved by researchers at the Gwangju Institute of Science and Technology as reported in the journal Nanotechnology.

: (September 17) Memristive behavior of magnetic tunnel junctions is reported by researchers from the Bielefeld University, Germany. A combination of resistive and magnetoresistive switching leads to a second order memristive device. The two state variables are the state of the insulating layer (oxygen vacancy positions) and the state of the magnetic electrodes (the relative orientation of the magnetization direction).

;2010 : (February, 17) A review on memristor and its modeling approaches is accepted to be published in the ''Proceedings of the Royal Society''.

: The 2nd Memristor and Memristive Systems Symposium was held on Tuesday, February 2, 2010 at Sutardja Dai Hall, UC Berkeley.

: (April 8) An array of memristors is demonstrated to perform logical functions.

:(April, 20) Memristor-based Content Addressable Memory (MCAM) is introduced and accepted in IEEE Transactions on Very Large Scale Integration (VLSI) Systems.

: (June 1) At the 2010 International Symposium on Circuits and Systems, there were two special sessions on memristor devices and fabrication. One of the presentations entitled "The mythology of the memristor" by Blaise Mouttet argued that the interpretation of the memristor as a fourth fundamental was incorrect and that the device discovered by HPLabs was not actually a memristor, but part of a broader class of memristive systems.

: (August 31) HP announced they teamed up with Hynix to produce a commercial product dubbed "ReRam".

: (October 15) At the 2010 IEEE Nanotechnology Materials and Devices Conference, A. Delgado presented the paper "The Memristor as Controller". This work introduces the memristor as a programmable gain for closed loop systems and derives an approximate describing function for the pinched hysteresis loop.

: (December 7) Ju-Hee So and Hyung-Jun Koo of North Carolina State University announced a hydrogel form of memristor which is speculated to be useful to construct a brain-computer interface.

;2013 : The first products using memristor technology are expected to become available.

See also

Chua (unit)

Memistor

Electrical element

List of emerging technologies

Physical neural network

RRAM

References

External links

Discovery: Memristors, BBC World Service, Thursday 17 March 2011

Hewlett Packard outlines computer memory of the future BBC News, Thursday, 8 April 2010

Technical FAQ by Memristor lead scientist, Stan Williams of HP Labs May 20, 2008

IEEE Spectrum - How We Found the Missing Memristor, by R. Stanley Williams Dec 2008

Memristive switching mechanism for metal/oxide/metal nanodevices July 15, 2008

Java simulations of memristor circuits Dec 3, 2008

Youtube video of 2008 Memristor and Memristive Systems Symposium at UC Berkeley

6-minute memristor guide by R. Stanley Williams (Youtube) December 10, 2008 IEEE Spectrum online

A detailed references list and links on memristors

A detailed references list and links on high-order nonlinear circuits elements

A talk on the progress the Boston University Neuromorphic Lab effort in building the memristor-based MoNETA model

The IEEE Spectrum "MoNETA: A Mind Made from Memristors" featuring the memristor-based neural model, December 1, 2010

Business Landscape of Memristor Electronics

Memristor processor solves mazes

Category:Electrical components Category:Emerging technologies

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name	Stanley Williams
image name	Stanley 'Tookie' Williams mugshot.jpg
birth name	Stanley Tookie Williams III
birth date	December 29, 1953
birth place	Shreveport, Louisiana,
death date	December 13, 2005
death place	San Quentin Prison, California, United States
charge	First degree murder with special circumstance
conviction penalty	Death penalty
conviction status	Executed
occupation	criminal,writer, philosopher,anti-gang activist.
children	}}

Stanley Tookie Williams III (December 29, 1953 – December 13, 2005) was the co-founder of the Crips, a notorious American street gang which had its roots in South Central Los Angeles in 1969. In 1979 he was convicted of four murders committed in the course of robberies and sentenced to death. Later on in his life, he became an author of several books including anti-gang and violence literature and children's books.

Williams refused to help police investigate his gang, and was implicated in attacks on guards and women, as well as multiple escape plots. In 1993, Williams began making changes in his behavior, and became an anti-gang activist while on Death Row in California. He renounced his gang affiliation and apologized for his role in founding the Crips. He also co-wrote children's books and participated in efforts intended to prevent youths from joining gangs. A biographical TV-movie entitled ''Redemption: The Stan Tookie Williams Story'' was made in 2004, and featured Jamie Foxx as Williams.

On December 13, 2005, Williams was executed by lethal injection after clemency and a four-week stay of execution were both rejected by Governor Arnold Schwarzenegger, amidst debate over the death penalty and whether Williams' anti-gang advocacy in prison represented genuine atonement for his crimes or was just a way to escape execution. Williams was the second inmate in California to be executed in 2005.

Childhood

Stanley Williams III was born December 29, 1953 at the New Orleans Charity Hospital in New Orleans, Louisiana to a 17-year old mother.

Williams' father abandoned the family when he was just a year old. Williams' mother hoped to escape the racism in the South and find prosperity in California, where many Blacks from the South were migrating to find better jobs. In 1959, at the age of five, Williams moved with his mother from New Orleans to Los Angeles, California by a Greyhound bus. His mother moved the two into an apartment on the West Side of South Central Los Angeles.

Because Williams' mother worked two and sometimes three jobs in order to support them, Williams was a latchkey kid and often engaged in mischief on the streets. Williams recalled that, as a child, he would hang out in abandoned houses and vacant lots around his neighborhood in South Central where he would watch adults get drunk, abuse drugs, gamble and engage in pit bull fights. Williams stated that after the adults finished the dog fighting they would make the children fight each other. Williams participated in these street fights regularly as a child where adults would bet on him and give him part of the proceeds for winning his fights. Williams was often the target of older bullies in his neighborhood and, by the age of twelve, he began carrying a switchblade in order to defend himself from older street hooligans.

Early delinquent behavior

By the time Williams reached his teens he had gained a reputation on the West Side as a vicious street fighter. Williams was expelled from several high schools in South Central L.A. for fighting and had begun doing stints in juvenile hall. Initially Williams despised the predatory street gangs in South Central. Because of his viciousness and willingness to fight older youths, many of whom belonged to small-time street gangs, Williams earned the respect of many neighborhood toughs on the West Side who were leaders of their own small-time cliques.

At age fifteen Williams befriended a teenager named Donald "Doc" Archie. Archie was part of a small-time West Side clique and Williams earned the clique's respect quickly after beating up one of their members for insulting his mother. As Williams' violent reputation began to spread across South Central L.A. he became the unofficial leader of this clique.

In 1970, at age sixteen, Williams was arrested in Inglewood, California for stealing a car and was sent to the Los Padrinos Juvenile Hall in Downey, California. While doing time at the detention center Williams was introduced to weightlifting by the facilities' gym coach. This experience would spark Williams' interest in bodybuilding as he became physically bigger and stronger by the time of his release from custody in early 1971. According to Williams, upon his release from custody, the review board asked him what he planned to do after being released. A seventeen year old Williams replied that he planned on "being the leader of the biggest gang in the world."

Founding of the Crips

Seventeen year-old Stanley Williams was approached by Raymond Washington in the spring of 1971, at Washington Preparatory High School. Washington was from the East Side of South Central, while Williams was from the West Side of that area. A mutual friend of both young men informed Washington of Williams' toughness and his willingness to fight members of larger, more established street gangs like the Brims and the Chain Gang (both gangs would later become Bloods sets; The L.A. Brims and The Inglewood Family Bloods respectively). According to Williams' account of his initial meeting with Washington what struck him about Washington was that, besides being incredibly muscular, Washington and his cohort were dressed similar to Williams and his clique (leather jackets with starched Levi's jeans and suspenders). They formed an alliance known first as the "Cribs," later changed to "Crips." (Ray Washington was killed in August 1979; his funeral took place on his birthday). Because Williams had befriended so many clique leaders and street toughs on the West Side, these leaders in turn rallied their members at Williams' behest and formed what would become the West Side Crips.

The purpose for creating the gang initially was to eliminate all street gangs and create a "bull force" neighborhood watch. Williams said: "We started out—at least my intent was to, in a sense, address all of the so-called neighboring gangs in the area and to put, in a sense—I thought 'I can cleanse the neighborhood of all these, you know, marauding gangs.' But I was totally wrong. And eventually, we morphed into the monster we were addressing." Washington himself has stated that he founded the Crips not with the intention of eliminating other gangs, but to create a force powerful enough to protect local black people from racism, corruption and brutality at the hands of the police.

At the time of the Crips' initial formation there were only three Crip sets: Washington's East Side Crips (later called East Coast Crips), Williams' West Side Crips and the Compton Crips, led by a teenager named Mac Thomas. Washington, Williams and Thomas went on an aggressive and violent recruitment campaign throughout the Black ghettos of Los Angeles. They challenged the leaders of other gangs to one-on-one street fights. Many gang leaders and their members acquiesed and joined the Crips.

Leader of the Crips

As leader of the West Side Crips Williams became the archetype of the new wave of Los Angeles gang members. Williams had become incredibly muscular as a result of his intense bodybuilding regimen and never missed an opportunity to display his physique, either in street fights or at social events like concerts or the annual Watts Fest. Williams' violent exploits as a gang leader were just as legendary as his huge biceps. With his best friend and "enforcer" Curtis "Buddha" Morrow Willliams would engage in random acts of violence against rival gang members and innocent people alike, striking fear in both street criminals and the residents of South Central, Watts and Compton. Perhaps what made his exploits even more legendary was the fact that on numerous occasions the criminal charges that were filed against him never stuck.

As other leaders of the Crips were either incarcerated or killed (in 1973 Raymond Washington was arrested for 2nd degree robbery and sentenced to five years in prison in Tracy, California, Curtis "Buddha" Morrow was shot to death in South Central L.A. in February of 1973 after a petty argument, Mac Thomas was ambushed and shot to death by Bloods in Compton in 1974) Williams was regarded as the leader of the Crips. Around this time Williams lived a dual life as a gang leader as well as a youth counselor in Compton, even studying Sociology at Compton College, however he spent his free time gangbanging and participated in numerous violent attacks against the Bloods.

In 1976, Williams was wounded in a drive-by shooting in Compton by members of the Bloods. While sitting on the front porch of a house he was living in several Bloods gang members opened fire on him from a moving car. Attempting to avoid getting hit Williams was shot in both of his legs as he dived off of the front porch. Despite being told by doctors that he wouldn't be able to walk again Williams began a nearly year-long process of rehabilitating himself through physical therapy and an intense workout regimen and ultimately regained his ability to walk.

Williams' drug use

Williams began dabbling in street drugs around the age of twelve. As a preteen Williams befriended a neighborhood pimp who, in return for Williams performing errands for him, would reward Williams with money and drugs particularly quaaludes, barbiturates (then known as "Red Devils") or marijuana. After being shot Williams began smoking angel dust; marijuana joints or cigarettes dipped in PCP (also known as "sherm" or "wet daddies"). PCP served two purposes for Williams: for one it gave him a psychotic edge in street fights and violent confrontations with rival gang members. PCP also gave Williams freakish strength and he used the drug as a sort of steroid in order to lift heavier weights when working out.

Williams' personal life began to unravel: his maternal grandmother with whom he was very close to passed away in 1976, he lost his counseling job in 1977 after being implicated in a robbery that was committed by two youths from a group home that Williams supervised, he was denied an opportunity to compete in an amateur bodybuilding contest after it was discovered that he was a gang leader (Williams would later appear on the 1970's variety show The Gong Show performing a posedown routine) and his gangbanger lifestyle was beginning to take a mental toll on him, which included a brief stay in the psychiatric ward of a hospital after Williams experienced a bad trip while high on PCP . With each of these setbacks Williams found himself using PCP more and more. To support his drug habit Williams would intimidate and/or rob drug dealers in South Central L.A. in order to obtain PCP. Williams' addiction to PCP would prove to be his undoing.

Crimes

In 1979 Williams was convicted of murder, in two separate incidents. Williams always maintained his innocence, though subsequent court reviews concluded that there was no compelling reason to grant a retrial.

Court transcripts state that Williams met with a man who is only identified in court documents as "Darryl" late on Tuesday evening, February 28, 1979. Williams introduced Darryl to a friend of his, Alfred Coward, a.k.a. "Blackie," a reference to his dark colored skin.

A short time after the initial meeting, Darryl, driving a brown station wagon and accompanied by Williams, drove to the home of James Garret. Williams frequently stayed with Garret, and kept some of his personal effects at that location including a 12-gauge shotgun. Williams went into the Garret residence, and in about ten minutes returned with the shotgun.

The three men then went to the home of Tony Sims in Pomona, California, where they discussed where they could go to make some money. Afterward, they went to another residence, where Williams left the others for a period of time. Upon returning, Williams produced a .22 caliber pistol, which he placed in the station wagon. Darryl and Williams got into the station wagon, Coward and Sims got into another vehicle, and shortly thereafter they were on the freeway.

Botched robbery

Both vehicles exited the freeway in the vicinity of Whittier Boulevard, where they drove to a nearby Stop-N-Go market. Darryl and Sims, at the request of Williams, entered the store with the apparent intention of robbing it. Darryl was carrying the .22 pistol that Williams had deposited in the station wagon earlier. Darryl also had an AK-47 assault rifle in the trunk of the car, along with two semi-automatic handguns.

The clerk at the Stop-N-Go market, Johnny Garcia, had just finished mopping the floor when he observed a station wagon and four black men at the door to the market. Two of the men entered the market. One of the men went down an aisle while the other approached Garcia.

The man that approached Garcia asked for a cigarette. Garcia gave the man a cigarette and lit it for him. After approximately three to four minutes, both men left the market without carrying out the planned robbery.

The 7-Eleven murder

Transcripts show that next Coward and Sims followed Williams and Darryl to the 7-Eleven market located at 10437 Whittier Boulevard, in Whittier, California. The store clerk, twenty-six year old Albert Lewis Owens, was sweeping the store at 7:42 p.m. in the parking lot. When Darryl and Sims entered the 7-Eleven, Owens put the broom and dustpan he was using on the hood of his car and followed them into the store. Williams and Coward then followed Owens into the store. Court records show that as Darryl and Sims walked to the counter area to take money from the register, Williams walked behind Owens, pulled the shotgun from under his jacket and told Owens to "shut up and keep walking."

While pointing the shotgun at Owens’ back, Williams directed him to a back storage room and ordered him to lie down. Coward said that he next heard the sound of a round being chambered into the shotgun. He then heard a shot and glass breaking, followed by two more shots. Records show that he shot out a security monitor and then killed Owens, shooting him twice in the back at point blank range as he lay prone on the storage room floor.

The Brookhaven Motel murders

The Yang family, husband seventy-six year old Yen-Yi Yang, and wife sixty-three year old Tsai-Shai C. Yang, were immigrants from Taiwan. They ran the Brookhaven Motel located at 10411 South Vermont Avenue in South Central Los Angeles along with their forty-three year old daughter, Yu-Chin Yang Lin, and son Robert. Yu-Chin had recently joined them from Taiwan.

According to court transcripts, at approximately 5:00 a.m. on March 11, 1979, Stanley Williams entered the Brookhaven Motel lobby and then broke down the door that led to the private office. Inside the office, Williams shot and killed Yen-Yi, Tsai-Shai, and Yu-Chin, after which he emptied the cash register and fled the scene.

Robert, asleep with his wife in their bedroom at the motel, was awakened by the sound of somebody breaking down the door to the motel’s office. Shortly thereafter he heard a female scream, followed by gunshots. Robert entered the motel office and found that his mother, his sister, and his father had all been shot; the cash register was empty.

The forensic pathologist testified that Yen-Yi Yang suffered two close range shotgun wounds, one to his left arm and abdomen, and one to the lower left chest. Tsai-Shai also received two close range wounds, one to the tailbone, and the other to the front of the abdomen, entering at the navel. Yee-Cheen Lin was shot once in the upper left face area at a distance of a few feet.

Witnesses testified that Williams referred to the victims in conversations with friends as "Buddha-heads", a derogatory term for Asians.

Conviction

Stanley Williams was convicted in 1979 of all four murders with special circumstances on each count of felony murder (robbery) as well as multiple murder in the case of the Brookhaven event. The jury also convicted him of robbery in both cases, and found that he personally used a firearm in the commission of the crimes. The jury recommended the death penalty, and the judge accepted the recommendation and sentenced him to death.

From the beginning of his sentence, Williams maintained his innocence regarding the four murders, alleging prosecutorial misconduct, exclusion of exculpatory evidence, ineffective assistance of counsel, biased jury selection, and the misuse of jailhouse and government informants. Williams claimed that the police found "not a shred of tangible evidence, no fingerprints, no crime scenes of bloody boot prints. They didn't match my boots, nor eyewitnesses. Even the shotgun shells found conveniently at each crime scene didn't match the shotgun shells that I owned." However, the prosecution's firearms expert, a sheriff's deputy, testified during trial that the shotgun shell recovered from the Yang murder crime scene matched test shells from the shotgun owned by Stanley Williams. No second examiner verified his findings. The Defense claims this expert's methodology was "junk science at best."

Williams' gun was found in the home of a couple with whom he occasionally stayed. According to the District Attorney, the husband was undergoing sentencing for receiving stolen property and tried for extortion. Williams' lawyers have claimed that the District Attorney quashed a murder investigation in exchange for their testimony. The two shells recovered from the Owens crime scene were consistent with shells fired from this gun, with no exclusionary markings. The shell recovered from the Yang crime scene was conclusively matched to Williams' weapon "to the exclusion of all other firearms."

Critics claim that although he renounced gangs and apologized for his role in co-founding the Crips, Williams continued to associate with Crips members in prison. However, when contacted about Williams' alleged ongoing gang activity, Los Angeles Police Department spokeswoman April Harding said there was no evidence of his gang leadership. Opponents also pointed out that he received a significant amount of money from outside sources. They stated that people who appreciate Williams' work sent him money. "It's as simple as that," said Williams' spokeswoman Barbara Becnel.

The prosecution removed three blacks from serving as jurors in Williams' trial. Williams' lawyers claimed that he was convicted by a jury that had no blacks, one Latino, one Filipino-American, and ten caucasians. The District Attorney provided proof, however, in the form of a death certificate and the sworn affidavit of another juror, that juror #12, William James McLurkin, was black. The defense responded that, contrary to the sworn affidavit, McLurkin did not appear black. They maintain that the trial record indicates that none of the lawyers—and particularly the prosecutor—thought Mr. McLurkin was black. McLurkin's driver license photo and the fact that both he and his mother were born in the Philippines was presented as additional evidence in a November 2005 petition for clemency. The defense, however, has neither stated whether or not his mother was actually Filipina, nor refuted the evidence that McLurkin was black.

According to the clemency petition, in his closing arguments, prosecuting District Attorney Robert Martin described Williams as a "Bengal tiger in captivity in a zoo" and said that the jury needed to imagine him in his natural "habitat" which was like "going into the back country, into the hinterlands." In a radio interview, Martin stated that the analogy was not meant to be racial, and instead was a metaphor to the fact that Williams appeared in court dressed in business attire much like an animal in a zoo appears more docile than it would be in the wild.

Williams threatens jurors

In the Court of Appeals summary of the case, Williams stated that various jurors misconstrued as a threat a question that he asked defense counsel at the close of the guilt phase. The trial record shows that after the jurors returned their guilty verdicts, Williams said, 'Sons of bitches,' in a voice sufficiently loud that the court reporter included this statement in the trial transcript. "On the day that the jury began its penalty-phase deliberations, an alternate juror reported to the bailiff that he was going to get all of them."

Prison life

As inmate CDC# C29300 at San Quentin State Prison Williams spent 6½ years in solitary confinement in the late 1980s for multiple assaults on guards and fellow inmates. According to a classification report found on page 8 of filings by his lawyers during the clemency proceedings dated August 5, 2004, Williams had no violations since that time.

Challenges to the conviction

Appeals

Williams appealed his conviction in the state courts, and filed a petition in the federal courts for habeas corpus relief. The State courts affirmed the conviction. The lower federal court denied the habeas petition. In 2001, the United States Court of Appeals for the Ninth Circuit heard Williams' appeal from the lower federal court. The appellate court denied Williams' appeal in 2002, but noted that the federal courts were not his only forum for relief and that he could request clemency from the Governor of California.

Activist response and community reaction

In late 2005, a campaign began to urge Governor Arnold Schwarzenegger to grant clemency for Williams in consideration of his work as an anti-gang activist and asserted "redemption." Thousands of people signed online petitions calling for Schwarzenegger to commute the death sentence. Those who campaigned against the execution included entertainers, politicians, and Nobel laureates. In early November, 2005, Williams' attorneys filed his formal petition for executive clemency, as well as a motion to obtain new evidence. (See below for the full text of the documents filed in these proceedings.)

The state, through the office of the Los Angeles County District Attorney, opposed the clemency petition. The Los Angeles Police Department, the Los Angeles County District Attorney, and other law enforcement groups disputed that Williams had in fact reformed, saying that he refused to divulge information on other gang members, or debrief officials on the tactics and communication methods that gangs use. Williams said he didn't want to be a "snitch."

The clemency petition emphasized the theme of Williams' redemption, rather than his claim of actual innocence. At least one commentator felt this strategy was flawed: San Francisco Chronicle writer Bob Egelko noted doubts stated by the courts handling the appeals and quoted Austin Sarat, professor of law and politics at Amherst College in Massachusetts and author of ''Mercy on Trial,'' a book about clemency: ''"It's [actual innocence] about the only ground in which governors grant clemency in the modern period...I know of no case in which a death row inmate has been spared (solely) on the basis of post-conviction rehabilitation."''

On December 8, 2005, Governor Schwarzenegger held a clemency hearing. The one-hour, closed-door meeting took place as a crowd consisting of both supporters of Williams and proponents of capital punishment congregated outside the Capitol in Sacramento. Schwarzenegger described the decision whether to grant clemency as "the toughest thing when you are governor, dealing with someone's life."

While the clemency petition was pending before the governor, Williams also filed further appeals in the courts. On November 30, 2005, the California Supreme Court, in a 4-3 decision, refused to reopen Williams' case. On December 11, 2005, the California Supreme Court denied Williams' request for a stay of execution. Supporters of Williams also made another plea directly to Governor Schwarzenegger to stay the execution.

Also during this period, the media, community organizations, and relatives of the victims were speaking out. In mid-November 2005, talk show hosts John and Ken of the ''John and Ken Show'' on Clear Channel's KFI radio in Los Angeles, California started a "Tookie Must Die (For Killing Four Innocent People)" hour on their show daily until the execution of Williams. In the hour, they interviewed advocates of both sides of the issue and expressed their support of the impending execution.

Many anti-death penalty and civil rights organizations around the country organized activist campaigns to stop the execution, including the Campaign to End the Death Penalty, the NAACP, A.N.S.W.E.R., and others. Tookie's friend, co-author and political collaborator, Barbara Becnel, helped to spearhead much of the organizing. Celebrities also joined the fight, including Snoop Dogg, who appeared at a clemency rally wearing a shirt advertising the Save Tookie website and performed a song he had written for Williams, and Jamie Foxx, who - noting that Tookie's execution date was his birthday - publicly stated that the only birthday present he wanted was clemency for Williams. Other prisoners were also involved in activism to save Williams's life. Tony Ford, whose death sentence in a disputed case has been indefinitely stayed, helped organize a prisoners' strike in Texas protesting Williams' execution.

On November 29, 2005, the American Civil Liberties Union of Northern California announced that more than 175,000 Californians had signed a petition requesting the temporary suspension of executions in California until the California Commission on the Fair Administration of Justice could complete its study, due by December 31, 2007. The "California Moratorium on Executions Act", A.B.1121, is scheduled to have its first hearing in January 2006. Press conferences and rallies in more than a dozen California cities called for a halt to all executions and asked Governor Schwarzenegger to commute Williams’ death sentence to a sentence of life without parole; demonstrations against the death penalty also took place in numerous cities around the world.

On December 8, 2005, Lora Owens, the stepmother of Albert Owens, one of the victims, made a statement expressing her opinion of Stanley Williams: "I think he [Williams] is the same cold-blooded killer that he was then and he would be now if he had the opportunity again." Owens' two daughters, Rebecca and Andrea, who were 8 and 5 when their father was murdered, also opposed clemency and recalled that they were aghast when they had learned that their father's murderer was nominated for a Nobel Peace Prize.

By contrast, on December 9, 2005, Linda Owens, Albert Owens' widow, issued a statement in support of Williams’ efforts to bring an end to gang violence and his call for peace between gangs: "I, Linda Owens want to build upon Mr. Williams' peace initiative. I invite Mr. Williams to join me in sending a message to all communities that we should all unite in peace. This position of peace would honor my husband's memory and Mr. Williams work."

The Governor denies clemency

On December 12, 2005, Governor Schwarzenegger denied clemency for Williams. In his denial, Governor Schwarzenegger cited the following:

"The possible irregularities in Williams’ trial have been thoroughly and carefully reviewed by the courts, and there is no reason to disturb the judicial decisions that uphold the jury’s decisions that he is guilty of these four murders and should pay with his life."

The basis of his request for clemency is the "personal redemption Stanley Williams has experienced and the positive impact of the message he sends," yet "it is impossible to separate Williams' claim of innocence from his claim of redemption."

"Cumulatively, the evidence demonstrating Williams is guilty of these murders is strong and compelling...there is no reason to second guess the jury’s decision of guilt or raise significant doubts or serious reservations about Williams’ convictions and death sentence."

"Williams has written books that instruct readers to avoid the gang lifestyle and to stay out of prison...(h)e has also...tried to preach a message of gang avoidance and peacemaking...(i)t is hard to assess the effect of such efforts in concrete terms, but the continued pervasiveness of gang violence leads one to question the efficacy of Williams' message."

"The dedication of Williams' book ''Life in Prison'' casts significant doubt on his personal redemption… the mix of individuals on [the dedication] list is curious… (b)ut the inclusion of George Jackson on the list defies reason and is a significant indicator that Williams is not reformed and that he still sees violence and lawlessness as a legitimate means to address societal problems."

"Is Williams’ redemption complete and sincere, or is it just a hollow promise? Stanley Williams insists he is innocent, and that he will not and should not apologize or otherwise atone for the murders of the four victims in this case. Without an apology and atonement for these senseless and brutal killings there can be no redemption. In this case, the one thing that would be the clearest indication of complete remorse and full redemption is the one thing Williams will not do."

Governor Schwarzenegger summarized by basing his denial of clemency on the "totality of circumstances."

Last legal efforts to save Williams

On the same day the governor denied Williams clemency, Jonathan Harris, a New York counsel with Curtis, Mallet-Prevost, Colt & Mosle LLP, filed a response summarizing new evidence of innocence.

It included reference to an affidavit by Gordon Bradbury von Ellerman attesting to belief in Williams' innocence. Dated December 10, it states that he called the NAACP on December 8 after reading in the ''Daily Breeze'' that his cellmate, George Oglesby, had testified against Williams. He states that he had observed Oglesby receive police reports on Williams and others. Mr. Oglesby told Von Ellerman that he was using the documents to testify against Williams and others "to gain a reduction or eliminate charges against him." Von Ellerman also observed Oglesby copying from samples of Williams' handwriting to "create incriminating documents that would appear to be written by Mr. Williams." Prosecutors had cited handwritten notes written by Mr. Williams about an escape plan which involved the killing of a bus driver and another accomplice.

Execution

On December 13, 2005, after exhausting all forms of appeal, Williams was executed by lethal injection at San Quentin State Prison, California. ''Newsweek'' reported thousands of protesters outside, most of whom were seeking Williams' clemency. He was the 12th person to be executed by the state following the 1976 U.S. Supreme Court decision of ''Gregg v. Georgia''.

Williams provided no last words to the prison warden. In an interview on WBAI Pacifica radio hours before the execution, he stated:

"My lack of fear of this barbaric methodology of death, I rely upon my faith. It has nothing to do with machismo, with manhood, or with some pseudo former gang street code. This is pure faith, and predicated on my redemption. So, therefore, I just stand strong and continue to tell you, your audience, and the world that I am innocent and, yes, I have been a wretched person, but I have redeemed myself. And I say to you and all those who can listen and will listen that redemption is tailor-made for the wretched, and that's what I used to be…That's what I would like the world to remember me. That's how I would like my legacy to be remembered as: a redemptive transition, something that I believe is not exclusive just for the so-called sanctimonious, the elitists. And it doesn't—is not predicated on color or race or social stratum or one's religious background. It's accessible for everybody. That's the beauty about it. And whether others choose to believe that I have redeemed myself or not, I worry not, because I know and God knows, and you can believe that all of the youths that I continue to help, they know, too. So with that, I am grateful…I say to you and everyone else, God bless. So take care."

Witnesses described the mood in the execution chamber as somber, and Williams showed no resistance as he was led into the execution chamber. After Williams was strapped to the gurney, he struggled against the straps holding him down to look up at the press gallery behind him, and to exchange glances with his supporters.

Williams's advocate and editor Barbara Becnel was also a witness to Williams's execution. In the epilogue of Williams's reprinted memoir, ''Blue Rage, Black Redemption'', Becnel reported that prior to Williams's arrival in the death chamber, he had promised her that "he would find a way to lift his head and smile at me at some point during his execution, no matter what was being done to him. And that is exactly what he did."

Williams then rested his head on the gurney while medical technicians began inserting needles in his veins, although CNN reported the staff had difficulty inserting the needles and the usually-short process took almost 20 minutes.

''Contra Costa Times'' reporter John Simerman added, "They had some trouble with the second I.V., which was in the left arm… Williams, at one point, grimaced or looked almost out of frustration…at the difficulty there…He had his glasses on the whole time. He kept them on, and he kept looking…"

With a look of frustration on his face, Williams angrily asked the technicians, "You guys doing that right?" A female guard whispered to him, and a second guard patted Williams' shoulder as if to comfort him. Williams shed one silent tear but otherwise showed no emotion as he died. Members of Albert Owens' family who witnessed the execution were described as stony-faced; however, Lora Owens appeared very upset, according to MSNBC anchor Rita Cosby.

Kevin Fagan, a reporter for the ''San Francisco Chronicle'', wrote a detailed description of the execution:

"This is the sixth one I have seen here at San Quentin, and I have to say this was very different. The most notable thing was that Williams had supporters at the back of the room… Mrs. Becnel was among them, I understand. We could see them, and throughout the last part of the execution—or preparing him when he was still conscious, they gave what looked like black power salutes several times to him, one man and two women. And most strikingly at the end of the execution, as those three were heading out, they yelled, 'The State of California just killed an innocent man!' which is the first time I ever heard any outburst in the death chamber there."

After Williams was pronounced dead at 12:35 a.m. PST (08:35 UTC), several reporters who witnessed the execution held a news conference.

Aftermath

Williams' spokeswoman and co-author, Barbara Becnel, said shortly after Williams's death that she is "now on a mission" to obtain justice for Stanley Tookie Williams. Williams directed Becnel to receive his body and Becnel began making the funeral arrangements.

Becnel reacted to Williams' execution by saying "We are going to prove his innocence, and when we do, we are going to show that Gov. Arnold Schwarzenegger is, in fact, himself a cold blooded murderer."

Williams' body was laid out for viewing on December 19, 2005 and drew approximately 2,000 mourners. A memorial service was held in Los Angeles on December 20, 2005, where Becnel read his final wishes. Williams' funeral filled the 1,500 seat Bethel AME church and drew a wide variety of people from current gang members to celebrities and religious leaders. On June 25, 2006, Barbara Becnel and Williams' longtime friend, Shirley Neal, sprinkled his ashes into a lake in Thokoza Park in the city of Soweto, South Africa as Williams had wished.

At his funeral, the last words of Williams echoed from a tape played to mourners, whom he asked to spread a message to loved ones:

:"The war within me is over. I battled my demons and I was triumphant."

:"Teach them how to avoid our destructive footsteps. Teach them to strive for higher education. Teach them to promote peace and teach them to focus on rebuilding the neighborhoods that you, others, and I helped to destroy."

Rapper Snoop Dogg, himself a former Crip, recited a poem to mourners about the execution:

:''"It's 9:15 on 12/13 and another black king will be taken from the scene."'' Crips Gang member and rapper, WC, made a reference to the execution of Williams on his album ''Guilty by Affiliation'': "Charles Manson can kill and live to see another day, but if you're black like Tookie they're gonna steal you away."

Governor Schwarzenegger's decision provoked outrage in his home town of Graz, Austria. Local politicians submitted a petition to the City Council to remove his name from the local stadium, which was backed by a majority on the council. Before the vote was taken, Schwarzenegger asked for the name of the stadium to be changed, since he and Graz council members were not of one mind on the issue.

Williams' children

Travon Williams, the older son by Bonnie Williams-Taylor, whom Williams wed in 1981 before his conviction, was 32 years old at the time of his father's execution. Williams-Taylor talked to her ex-husband by phone that day. "He was great. He said he was at peace with himself and proud of his son," who avoided the gang life, according to Leslie Fulbright, a staff writer for the ''San Francisco Chronicle''. Travon is married, a father, owns a home and works for a social services agency in the Los Angeles area, said Barbara Becnel, Stanley Williams' co-author.

Travon was the only family member who spoke at the funeral. Williams' son "brought the church to its feet" when he promised to teach Schwarzenegger about redemption. He said, "I feel it's my duty to go on a worldwide campaign to show that redemption is real," he said.

Stanley Williams' other son, Stanley "Little Tookie" Williams, IV, a Neighborhood Crip, was found guilty of shooting a 20-year-old woman to death in an alley off Sunset Boulevard in Hollywood. Williams IV was sentenced to sixteen years in prison for second-degree murder.

In November 2005, the Fontana, California Police Department advised print and television media that a warrant had been issued for a registered sex offender, Lafayette Jones. The police department identified Jones as the son of Stanley Tookie Williams. The defense of Stanley Tookie Williams stated that this was a lie purported by the police department, and in their Reply Petition for Executive Clemency, they attached a declaration from Lafayette Jones' mother which declared, under penalty of perjury, that Jones was not Stanley Tookie Williams' son.

References

Books by Williams

Magazines

San Francisco Magazine 2006

Notes

External links

Transcript and audio of interview with Williams (Democracy Now!)

People v. Williams (1988) 44 C3d 1127, Habeas Corpus filed on behalf of Williams

Transcript and audio of interview with Tookie a few hours before his execution with Democracy Now!

The Crimes of Tookie Williams (About.com)

Webcast of Williams' memorial service

Stan "Tookie" Williams Memorial at Find A Grave

Stanley Williams. ''California Department of Corrections and Rehabilitation''. Retrieved on 2007-11-12.

Obituary

"''American Gangster:'' Tookie Williams & The Rise of the Crips" by Alan Kurtz (Blogcritics)

Legal documents

PDF files:

* Motion for Post Judgment Discovery (savetookie.org)

* Executive Clemency petition filed by Curtis, Mallet-Prevost, Colt & Mosle LLP, from the law firm's website

* Los Angeles County District Attorney's Response to Clemency petition from the District Attorney's website

* Executive Clemency Reply petition filed by Curtis, Mallet-Prevost, Colt & Mosle LLP, from the law firm's website

* Stanley Williams v. Jill Brown, filed in the Supreme Court of the United States of America - www.streetgangs.com

News articles

''Snoop Dogg, Barbara Becnel and Minister Tony Muhammad speak at Rally'', ''Alex Alonso'', November 21, 2005.

''"Stanley Tookie Williams, Could be First Gang Member Executed in California"'', ''Alex Alonso'', December 10, 2005. Retrieved December 21, 2005.

''"Tookie’s Mistaken Identity; On the trail of the real founder of the Crips", L.A. Weekly, December 16–22, 2005. Retrieved December 21, 2005.

''"Watching Williams die", Contra Costa Times, December 13, 2005.

Category:1953 births Category:2005 deaths Category:20th-century American criminals Category:21st-century executions by the United States Category:Activists from the San Francisco Bay Area Category:American activists Category:American people convicted of murder Category:American robbers Category:California criminals Category:Crips Category:Executed African-American people Category:History of Los Angeles, California Category:People convicted of murder by California Category:People executed by California Category:People executed by lethal injection Category:People executed for murder Category:People from Monroe, Louisiana Category:People from Los Angeles, California

cs:Stanley Williams cz:Stanley Williams da:Stanley "Tookie" Williams de:Stanley Williams es:Stanley Williams eo:Stanley Williams fr:Stanley Williams ko:스�?�리 윌리엄스 it:Stanley Williams he:ס�?נלי וילי�?מס hu:Stanley Williams nl:Stanley Williams ja:スタ�?��?��?��?�ウィ�?�ア�?�ズ pl:Stanley Williams pt:Stanley Williams ru:Уильям�?, Стэнли fi:Stanley Williams sv:Stanley Williams

Name	Leon Chua
Birth date	June 28, 1936
Birth place	Philippines
Residence
Citizenship
Nationality
Ethnicity	Han Chinese
Fields	Electronic Engineer
Workplaces	University of California, Berkeley
Alma mater	Mapúa Institute of Technology Massachusetts Institute of Technology
Doctoral students	See: Ph.D. Dissertations supervised by Chua
Known for	Nonlinear circuit theory Cellular neural networks Memristor Chua's circuit Chaotic digital CDMA
Awards	IEEE W.R.G. Baker Prize Paper Award
Signature
Footnotes	He is the father of Amy Chua. }}

Leon Ong Chua (; ; born June 28, 1936) is an IEEE Fellow and a professor in the electrical engineering and computer sciences department at the University of California, Berkeley, which he joined in 1971. Considered to be the "father of nonlinear circuit theory and cellular neural networks", he is also the inventor and namesake of Chua's circuit and was the first to conceive the theories behind, and postulate the existence of, the solid-state memristor. Thirty-seven years after he predicted its existence, a working solid-state memristor was created by a team led by R. Stanley Williams at Hewlett Packard.

Early life and education

A Chinese American, Chua and his fraternal twin sister grew up as members of the Chinese ethnic minority community in the Philippines under the reign of the Empire of Japan during World War II. He earned his BSEE degree from Mapúa Institute of Technology in the Philippines in 1959, then emigrated to the United States on a scholarship to the Massachusetts Institute of Technology, where he earned an MSEE degree in 1961. He then earned a Ph.D from the University of Illinois, Urbana-Champaign in 1964. His PhD thesis was entitled ''Nonlinear Network Analysis----The Parametric Approach.'' Over the ensuing years, he has received eight honorary doctorates.

Chua has four daughters; the eldest, Amy Chua (a Professor of Law at Yale University.), Michelle, Katrin (a professor at Stanford University), and Cynthia (Cindy).

Career

Chua was a member of the faculty at Purdue University from 1964-1970 before joining Berkeley in 1971. His current research interests include cellular neural/nonlinear networks, nonlinear circuits and systems, nonlinear dynamics, bifurcation theory, and chaos theory. He is also the Editor of The International Journal of Bifurcation and Chaos.

Awards and honors

''Doctor Honoris Causa'' from the École Polytechnique Fédérale de Lausanne, Switzerland (1983) Honorary Doctorate from the University of Tokushima, Japan (1984) Honorary Doctorate from the Technische Universität Dresden, Germany (1992) '' Doctor Honoris Causa'' from the Technical University of Budapest, Hungary (1994) ''Doctor Honoris Causa'' from the University of Santiago de Compostela, Spain (1995) ''Doctor Honoris Causa'' from the University of Frankfurt, Germany (1996) ''Doctor Honoris Causa'' from the Gheorghe Asachi Technical University of Iaşi, Romania (1997) ''Doctor Honoris Causa'' from the University of Catania, Italy (2000) IEEE Browder J. Thompson Memorial Prize Award (1967) IEEE Guillemin-Cauer Award (1972, 1985, 1989) IEEE W.R.G. Baker Prize Paper Award (1973), for the paper '' "Memristor: The Missing Circuit Element" in IEEE TRANSACTIONS on Circuit Theory, September 1971'' IEEE Neural Networks Pioneer Award (2000) IEEE Gustav Robert Kirchhoff Award (2005), ''For seminal contributions to the foundation of nonlinear circuit theory, and for inventing Chua's Circuit and Cellular Networks, each spawning a new research area.''

M. E. Van Valkenburg Award (1995 and 1998)

IEEE Circuits and Systems Society Vitold Belevitch Award (2007), ''For seminal contributions to nonlinear circuit theory, the first mathematically proven physical implementation of Chaos (Chua circuit), the local activity principle as the root of complexity, the cellular neural/nonlinear network principle and basic theory, and the qualitative theory of complexity in 1D cellular automata.''

2010 Guggenheim Fellowship

References

Category:1936 births Category:Living people Category:American people of Chinese descent Category:Mapúa Institute of Technology alumni Category:University of California, Berkeley faculty Category:American electrical engineers Category:Fellow Members of the IEEE Category:Massachusetts Institute of Technology alumni Category:University of Illinois at Urbana–Champaign alumni

ceb:León Chua de:Leon Chua es:Leon Ong Chua fr:Leon Chua no:Leon Ong Chua pt:Leon Ong Chua sv:Leon Chua zh:蔡少棠 vi:Thái Thiếu �?ường