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Zlil Sela: Automorphisms of groups and a higher rank JSJ decomposition
Atelier sur Groupes autour de 3-variétés/ Workshop on Groups around 3-Manifolds (Juin/June 05-16 2023)
Juin/June 12 :
Webpage : https://www.crmath.ca/en/activities/#/type/activity/id/3857
Program: https://crm.umontreal.ca/2023/3Manifolds/pdf/schedule-Manifolds-w2.pdf
The JSJ decomposition encodes the automorphisms and the virtually cyclic splittings of a hyperbolic group. For general finitely presented groups, the JSJ decomposition encodes only their splittings. We generalize the structure and the construction of the JSJ decomposition, to study the automorphisms of a (colorable) hierarchically hyperbolic group that satisfies some weak acylindricity conditions. The object that we construct can be viewed as a higher rank JSJ decomposition. Like the JSJ decomposition of a hyperbolic group ...
published: 13 Jul 2023
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Zlil Sela - Automorphisms of groups and a higher rank JSJ decomposition
The JSJ (for groups) was originally constructed to study the automorphisms and the cyclic splittings of a (torsion-free) hyperbolic group. Such a structure theory was needed to complete the solution of the isomorphism problem for (torsion-free) hyperbolic groups.
Later, the JSJ was generalized to all finitely presented groups. In this generality it encodes the splittings but not all the automorphisms.
We further generalize the JSJ decomposition to study automorphisms of groups that act on products of hyperbolic spaces, and more generally to study automorphisms of (some) hierarchically hyperbolic groups (e.g. right angled Artin groups). The object that we construct can be viewed as a higher rank JSJ decomposition.
published: 06 Sep 2021
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NCNGT2020: Volume Conjecture, geometric decomposition and deformation of hyperbolic structures (II)
Hi everyone! This to the second and the last talk of the series "Volume Conjecture, geometric decomposition and deformation of hyperbolic structures".
Last time, we discussed how the asymptotics of the quantum invariants for hyperbolic links and 3-manifolds are related to 3 dimensional hyperbolic geometry. This time, we will focus on some satellite links whose complements have more than one hyperbolic piece in the geometric decomposition, and relate the asymptotics of their colored Jones polynomials to the geometric structures on the geometric pieces.
Preprints are available on arxiv:
- Asymptotics of some quantum invariants of the Whitehead chains,
https://arxiv.org/abs/1912.10638
- Volume conjecture, geometric decomposition and deformation of hyperbolic structures
https://arxiv.org/ab...
published: 24 May 2020
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Benjamin Barrett: Gromov boundaries and Bowditch's JSJ decomposition
It is a fundamental principle in geometric group theory that large scale geometric properties of metric spaces on which a group acts should be considered properties of the group itself. If a given group acts on a hyperbolic metric space, then a particularly natural example of such a large-scale property is the Gromov boundary of that space: this is a topological space that compactifies the hyperbolic space at infinity. Connectivity properties of this boundary tell us how we can cut the group up into simpler pieces: a famous theorem of Stallings says that the group splits (as an amalgamated product or HNN extension) over a finite group if and only if the boundary is disconnected. In fact, one can say more: work of Brian Bowditch tells us that the structure of the collection of local cut poi...
published: 02 Apr 2021
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Complexities of 3-manifolds
Knots and Spatial Graphs 2015
Complexities of 3-manifolds/ Jae Choon Cha (POSTECH)/ 2015-11-06
published: 24 May 2017
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Symplectic fillings of lens spaces / Austin Christian / NCNGT 2021
Using the JSJ decomposition for symplectic fillings developed in our first talk, we complete the classification (up to diffeomorphism) of exact symplectic fillings of lens spaces. This is joint work with Youlin Li, and our result was independently obtained by John Etnyre and Agniva Roy.
This is the second of a pair of talks presented at NCNGT 2021. Here's the first: https://youtu.be/OQLa-E1bXCM
published: 07 Jun 2021
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Martin Bobb: Decomposition along flats for convex projective manifolds
Real convex projective geometry generalizes hyperbolic geometry in a way that allows for interesting deformation theory and also aspects of non-positive curvature. In this talk I will introduce convex projective geometry, and we will discuss a natural decomposition of compact convex projective manifolds along their codimension-1 flat substructures. This extends a celebrated 2006 result of Benoist: a 'geometric JSJ-decomposition' for compact convex projective 3-manifolds to manifolds of every dimension (greater than 2).
published: 26 Jun 2020
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"Conformal dimension and decompositions of hyperbolic groups," John Mackay, NYGT, 10/22/2021
"Conformal dimension and decompositions of hyperbolic groups," John Mackay (University of Bristol), New York Group Theory Seminar, 10/22/2021
published: 22 Oct 2021
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Geometry of complex surface singularities and 3-manifolds - Neumann
Geometric Structures on 3-manifolds
Topic: Geometry of complex surface singularities and 3-manifolds
Speaker: Walter Neumann
Date: Tuesday, January 26
I will talk about bilipschitz geometry of complex algebraic sets, focusing on the local geometry in dimension 2 (complex surface singularities), where the topological classification has long been understood in terms of 3-manifolds, while the analytic classification, even in this low dimension, is still very much out of reach. Bilipschitz geometry lies between the extremes of topological and analytic type. Although it leads to a "tame" classification (as first conjectured by Siebenmann and Sullivan in the 70's and proved by Mostowski in the mid-eighties), it is only in the last decade that the richness of the bilipschitz classification has b...
published: 26 Jan 2016
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"Geometric Topology of 3-manifolds" by Prof. Krüger Ramos Álvaro (Part.2/4)
Abstract: One of the greatest achievements on mathematics in the 21st century is the proof of the Poincaré's Conjecture by Grigory Perelman in 2003. Indeed, Perelman proved a much stronger result, which is the Geometrization Conjecture proposed by William Thurston in 1982. In order to do so, Perelman used the Ricci flow, a geometric/analytical argument proposed by Richard Hamilton. In this course, thought for a student with some background in Riemannian geometry, we will present Poincaré's conjecture in the context of the geometrization, explain the Geometrization theorem together with the eight Thurston's geometries and give an intuitive overview of the proof of Perelman.
☝️ Krüger Ramos Álvaro is professor at Universidade Federal do Rio Grande do Sul, Brazil.
This course was filmed at ...
published: 08 Dec 2022
52:35
Zlil Sela: Automorphisms of groups and a higher rank JSJ decomposition
Atelier sur Groupes autour de 3-variétés/ Workshop on Groups around 3-Manifolds (Juin/June 05-16 2023)
Juin/June 12 :
Webpage : https://www.crmath.ca/en/activi...
Atelier sur Groupes autour de 3-variétés/ Workshop on Groups around 3-Manifolds (Juin/June 05-16 2023)
Juin/June 12 :
Webpage : https://www.crmath.ca/en/activities/#/type/activity/id/3857
Program: https://crm.umontreal.ca/2023/3Manifolds/pdf/schedule-Manifolds-w2.pdf
The JSJ decomposition encodes the automorphisms and the virtually cyclic splittings of a hyperbolic group. For general finitely presented groups, the JSJ decomposition encodes only their splittings. We generalize the structure and the construction of the JSJ decomposition, to study the automorphisms of a (colorable) hierarchically hyperbolic group that satisfies some weak acylindricity conditions. The object that we construct can be viewed as a higher rank JSJ decomposition. Like the JSJ decomposition of a hyperbolic group it encodes information on the algebraic structure of the automorphism group and on the dynamics of individual automorphisms.
https://wn.com/Zlil_Sela_Automorphisms_Of_Groups_And_A_Higher_Rank_Jsj_Decomposition
Atelier sur Groupes autour de 3-variétés/ Workshop on Groups around 3-Manifolds (Juin/June 05-16 2023)
Juin/June 12 :
Webpage : https://www.crmath.ca/en/activities/#/type/activity/id/3857
Program: https://crm.umontreal.ca/2023/3Manifolds/pdf/schedule-Manifolds-w2.pdf
The JSJ decomposition encodes the automorphisms and the virtually cyclic splittings of a hyperbolic group. For general finitely presented groups, the JSJ decomposition encodes only their splittings. We generalize the structure and the construction of the JSJ decomposition, to study the automorphisms of a (colorable) hierarchically hyperbolic group that satisfies some weak acylindricity conditions. The object that we construct can be viewed as a higher rank JSJ decomposition. Like the JSJ decomposition of a hyperbolic group it encodes information on the algebraic structure of the automorphism group and on the dynamics of individual automorphisms.
- published: 13 Jul 2023
- views: 58
58:42
Zlil Sela - Automorphisms of groups and a higher rank JSJ decomposition
The JSJ (for groups) was originally constructed to study the automorphisms and the cyclic splittings of a (torsion-free) hyperbolic group. Such a structure theo...
The JSJ (for groups) was originally constructed to study the automorphisms and the cyclic splittings of a (torsion-free) hyperbolic group. Such a structure theory was needed to complete the solution of the isomorphism problem for (torsion-free) hyperbolic groups.
Later, the JSJ was generalized to all finitely presented groups. In this generality it encodes the splittings but not all the automorphisms.
We further generalize the JSJ decomposition to study automorphisms of groups that act on products of hyperbolic spaces, and more generally to study automorphisms of (some) hierarchically hyperbolic groups (e.g. right angled Artin groups). The object that we construct can be viewed as a higher rank JSJ decomposition.
https://wn.com/Zlil_Sela_Automorphisms_Of_Groups_And_A_Higher_Rank_Jsj_Decomposition
The JSJ (for groups) was originally constructed to study the automorphisms and the cyclic splittings of a (torsion-free) hyperbolic group. Such a structure theory was needed to complete the solution of the isomorphism problem for (torsion-free) hyperbolic groups.
Later, the JSJ was generalized to all finitely presented groups. In this generality it encodes the splittings but not all the automorphisms.
We further generalize the JSJ decomposition to study automorphisms of groups that act on products of hyperbolic spaces, and more generally to study automorphisms of (some) hierarchically hyperbolic groups (e.g. right angled Artin groups). The object that we construct can be viewed as a higher rank JSJ decomposition.
- published: 06 Sep 2021
- views: 713
24:53
NCNGT2020: Volume Conjecture, geometric decomposition and deformation of hyperbolic structures (II)
Hi everyone! This to the second and the last talk of the series "Volume Conjecture, geometric decomposition and deformation of hyperbolic structures".
Last tim...
Hi everyone! This to the second and the last talk of the series "Volume Conjecture, geometric decomposition and deformation of hyperbolic structures".
Last time, we discussed how the asymptotics of the quantum invariants for hyperbolic links and 3-manifolds are related to 3 dimensional hyperbolic geometry. This time, we will focus on some satellite links whose complements have more than one hyperbolic piece in the geometric decomposition, and relate the asymptotics of their colored Jones polynomials to the geometric structures on the geometric pieces.
Preprints are available on arxiv:
- Asymptotics of some quantum invariants of the Whitehead chains,
https://arxiv.org/abs/1912.10638
- Volume conjecture, geometric decomposition and deformation of hyperbolic structures
https://arxiv.org/abs/1912.11779
https://wn.com/Ncngt2020_Volume_Conjecture,_Geometric_Decomposition_And_Deformation_Of_Hyperbolic_Structures_(Ii)
Hi everyone! This to the second and the last talk of the series "Volume Conjecture, geometric decomposition and deformation of hyperbolic structures".
Last time, we discussed how the asymptotics of the quantum invariants for hyperbolic links and 3-manifolds are related to 3 dimensional hyperbolic geometry. This time, we will focus on some satellite links whose complements have more than one hyperbolic piece in the geometric decomposition, and relate the asymptotics of their colored Jones polynomials to the geometric structures on the geometric pieces.
Preprints are available on arxiv:
- Asymptotics of some quantum invariants of the Whitehead chains,
https://arxiv.org/abs/1912.10638
- Volume conjecture, geometric decomposition and deformation of hyperbolic structures
https://arxiv.org/abs/1912.11779
- published: 24 May 2020
- views: 88
1:04:39
Benjamin Barrett: Gromov boundaries and Bowditch's JSJ decomposition
It is a fundamental principle in geometric group theory that large scale geometric properties of metric spaces on which a group acts should be considered proper...
It is a fundamental principle in geometric group theory that large scale geometric properties of metric spaces on which a group acts should be considered properties of the group itself. If a given group acts on a hyperbolic metric space, then a particularly natural example of such a large-scale property is the Gromov boundary of that space: this is a topological space that compactifies the hyperbolic space at infinity. Connectivity properties of this boundary tell us how we can cut the group up into simpler pieces: a famous theorem of Stallings says that the group splits (as an amalgamated product or HNN extension) over a finite group if and only if the boundary is disconnected. In fact, one can say more: work of Brian Bowditch tells us that the structure of the collection of local cut points in the boundary determines a canonical JSJ decomposition for the group. In this talk I'll describe how Bowditch's JSJ decomposition is built from the structure of the boundary.
https://wn.com/Benjamin_Barrett_Gromov_Boundaries_And_Bowditch's_Jsj_Decomposition
It is a fundamental principle in geometric group theory that large scale geometric properties of metric spaces on which a group acts should be considered properties of the group itself. If a given group acts on a hyperbolic metric space, then a particularly natural example of such a large-scale property is the Gromov boundary of that space: this is a topological space that compactifies the hyperbolic space at infinity. Connectivity properties of this boundary tell us how we can cut the group up into simpler pieces: a famous theorem of Stallings says that the group splits (as an amalgamated product or HNN extension) over a finite group if and only if the boundary is disconnected. In fact, one can say more: work of Brian Bowditch tells us that the structure of the collection of local cut points in the boundary determines a canonical JSJ decomposition for the group. In this talk I'll describe how Bowditch's JSJ decomposition is built from the structure of the boundary.
- published: 02 Apr 2021
- views: 222
47:44
Complexities of 3-manifolds
Knots and Spatial Graphs 2015
Complexities of 3-manifolds/ Jae Choon Cha (POSTECH)/ 2015-11-06
Knots and Spatial Graphs 2015
Complexities of 3-manifolds/ Jae Choon Cha (POSTECH)/ 2015-11-06
https://wn.com/Complexities_Of_3_Manifolds
Knots and Spatial Graphs 2015
Complexities of 3-manifolds/ Jae Choon Cha (POSTECH)/ 2015-11-06
- published: 24 May 2017
- views: 159
25:25
Symplectic fillings of lens spaces / Austin Christian / NCNGT 2021
Using the JSJ decomposition for symplectic fillings developed in our first talk, we complete the classification (up to diffeomorphism) of exact symplectic filli...
Using the JSJ decomposition for symplectic fillings developed in our first talk, we complete the classification (up to diffeomorphism) of exact symplectic fillings of lens spaces. This is joint work with Youlin Li, and our result was independently obtained by John Etnyre and Agniva Roy.
This is the second of a pair of talks presented at NCNGT 2021. Here's the first: https://youtu.be/OQLa-E1bXCM
https://wn.com/Symplectic_Fillings_Of_Lens_Spaces_Austin_Christian_Ncngt_2021
Using the JSJ decomposition for symplectic fillings developed in our first talk, we complete the classification (up to diffeomorphism) of exact symplectic fillings of lens spaces. This is joint work with Youlin Li, and our result was independently obtained by John Etnyre and Agniva Roy.
This is the second of a pair of talks presented at NCNGT 2021. Here's the first: https://youtu.be/OQLa-E1bXCM
- published: 07 Jun 2021
- views: 29
49:21
Martin Bobb: Decomposition along flats for convex projective manifolds
Real convex projective geometry generalizes hyperbolic geometry in a way that allows for interesting deformation theory and also aspects of non-positive curvatu...
Real convex projective geometry generalizes hyperbolic geometry in a way that allows for interesting deformation theory and also aspects of non-positive curvature. In this talk I will introduce convex projective geometry, and we will discuss a natural decomposition of compact convex projective manifolds along their codimension-1 flat substructures. This extends a celebrated 2006 result of Benoist: a 'geometric JSJ-decomposition' for compact convex projective 3-manifolds to manifolds of every dimension (greater than 2).
https://wn.com/Martin_Bobb_Decomposition_Along_Flats_For_Convex_Projective_Manifolds
Real convex projective geometry generalizes hyperbolic geometry in a way that allows for interesting deformation theory and also aspects of non-positive curvature. In this talk I will introduce convex projective geometry, and we will discuss a natural decomposition of compact convex projective manifolds along their codimension-1 flat substructures. This extends a celebrated 2006 result of Benoist: a 'geometric JSJ-decomposition' for compact convex projective 3-manifolds to manifolds of every dimension (greater than 2).
- published: 26 Jun 2020
- views: 50
1:04:05
"Conformal dimension and decompositions of hyperbolic groups," John Mackay, NYGT, 10/22/2021
"Conformal dimension and decompositions of hyperbolic groups," John Mackay (University of Bristol), New York Group Theory Seminar, 10/22/2021
"Conformal dimension and decompositions of hyperbolic groups," John Mackay (University of Bristol), New York Group Theory Seminar, 10/22/2021
https://wn.com/Conformal_Dimension_And_Decompositions_Of_Hyperbolic_Groups,_John_Mackay,_Nygt,_10_22_2021
"Conformal dimension and decompositions of hyperbolic groups," John Mackay (University of Bristol), New York Group Theory Seminar, 10/22/2021
- published: 22 Oct 2021
- views: 170
58:45
Geometry of complex surface singularities and 3-manifolds - Neumann
Geometric Structures on 3-manifolds
Topic: Geometry of complex surface singularities and 3-manifolds
Speaker: Walter Neumann
Date: Tuesday, January 26
I will t...
Geometric Structures on 3-manifolds
Topic: Geometry of complex surface singularities and 3-manifolds
Speaker: Walter Neumann
Date: Tuesday, January 26
I will talk about bilipschitz geometry of complex algebraic sets, focusing on the local geometry in dimension 2 (complex surface singularities), where the topological classification has long been understood in terms of 3-manifolds, while the analytic classification, even in this low dimension, is still very much out of reach. Bilipschitz geometry lies between the extremes of topological and analytic type. Although it leads to a "tame" classification (as first conjectured by Siebenmann and Sullivan in the 70's and proved by Mostowski in the mid-eighties), it is only in the last decade that the richness of the bilipschitz classification has become evident. I will describe work of Lev Birbrair, Anne Pichon and myself, on bilipschitz classification of complex surface germs in terms of refined JSJ decomposition of their 3-manifold links plus associated rational invariants, and if time permits, also the relationship of the classification with Zariski equisingularity, which was Zariski's approach to a tame classification.
For more videos visit http;//video.ias.edu
https://wn.com/Geometry_Of_Complex_Surface_Singularities_And_3_Manifolds_Neumann
Geometric Structures on 3-manifolds
Topic: Geometry of complex surface singularities and 3-manifolds
Speaker: Walter Neumann
Date: Tuesday, January 26
I will talk about bilipschitz geometry of complex algebraic sets, focusing on the local geometry in dimension 2 (complex surface singularities), where the topological classification has long been understood in terms of 3-manifolds, while the analytic classification, even in this low dimension, is still very much out of reach. Bilipschitz geometry lies between the extremes of topological and analytic type. Although it leads to a "tame" classification (as first conjectured by Siebenmann and Sullivan in the 70's and proved by Mostowski in the mid-eighties), it is only in the last decade that the richness of the bilipschitz classification has become evident. I will describe work of Lev Birbrair, Anne Pichon and myself, on bilipschitz classification of complex surface germs in terms of refined JSJ decomposition of their 3-manifold links plus associated rational invariants, and if time permits, also the relationship of the classification with Zariski equisingularity, which was Zariski's approach to a tame classification.
For more videos visit http;//video.ias.edu
- published: 26 Jan 2016
- views: 2042
1:38:59
"Geometric Topology of 3-manifolds" by Prof. Krüger Ramos Álvaro (Part.2/4)
Abstract: One of the greatest achievements on mathematics in the 21st century is the proof of the Poincaré's Conjecture by Grigory Perelman in 2003. Indeed, Pe...
Abstract: One of the greatest achievements on mathematics in the 21st century is the proof of the Poincaré's Conjecture by Grigory Perelman in 2003. Indeed, Perelman proved a much stronger result, which is the Geometrization Conjecture proposed by William Thurston in 1982. In order to do so, Perelman used the Ricci flow, a geometric/analytical argument proposed by Richard Hamilton. In this course, thought for a student with some background in Riemannian geometry, we will present Poincaré's conjecture in the context of the geometrization, explain the Geometrization theorem together with the eight Thurston's geometries and give an intuitive overview of the proof of Perelman.
☝️ Krüger Ramos Álvaro is professor at Universidade Federal do Rio Grande do Sul, Brazil.
This course was filmed at ICTP (Trieste, Italy) from October 24 to 27, 2022.
------------------------------------------------
Follow CIMPA news:
Website: https://www.cimpa.info
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https://wn.com/Geometric_Topology_Of_3_Manifolds_By_Prof._Krüger_Ramos_Álvaro_(Part.2_4)
Abstract: One of the greatest achievements on mathematics in the 21st century is the proof of the Poincaré's Conjecture by Grigory Perelman in 2003. Indeed, Perelman proved a much stronger result, which is the Geometrization Conjecture proposed by William Thurston in 1982. In order to do so, Perelman used the Ricci flow, a geometric/analytical argument proposed by Richard Hamilton. In this course, thought for a student with some background in Riemannian geometry, we will present Poincaré's conjecture in the context of the geometrization, explain the Geometrization theorem together with the eight Thurston's geometries and give an intuitive overview of the proof of Perelman.
☝️ Krüger Ramos Álvaro is professor at Universidade Federal do Rio Grande do Sul, Brazil.
This course was filmed at ICTP (Trieste, Italy) from October 24 to 27, 2022.
------------------------------------------------
Follow CIMPA news:
Website: https://www.cimpa.info
Facebook: https://bit.ly/3sY8OdQ
Twitter: https://twitter.com/cimpa_math
LinkedIn: https:https://bit.ly/3rHfrRs
- published: 08 Dec 2022
- views: 58