Computation is any type of calculation or the use of computer technology in Information processing. Computation is a process following a well-defined model understood and expressed in an algorithm, protocol, network topology, etc. Computation is also a major subject matter of computer science: it investigates what can or cannot be done in a computational manner.

Computation can be classified by at least three orthogonal criteria: digital vs analog, sequential vs parallel vs concurrent, batch vs interactive.

In practice, digital computation is often used to simulate natural processes (for example, Evolutionary computation), including those that are more naturally described by analog models of computation (for example, Artificial neural network).

A computation can be seen as a purely physical phenomenon occurring inside a closed physical system called a computer. Examples of such physical systems include digital computers, mechanical computers, quantum computers, DNA computers, molecular computers, analog computers or wetware computers. This point of view is the one adopted by the branch of theoretical physics called the physics of computation.

Keith Gordon Downing (born 23 July 1965 in Oldbury) is an English former footballer. He made the vast majority of his appearances for Wolverhampton Wanderers, where he was nicknamed “Psycho” for his robust style playing in central midfield.

Downing began his professional career in 1984 at Notts County, after a spell at Mile Oak Rovers, before moving to Wolves in 1987. At Wolves he played over 200 league and cup games, scoring 11 goals in total, and helping the team to two successive promotions in the late 1980s.

In 1993 Downing moved to Birmingham City, but managed only one league game, before leaving for Stoke City and later Cardiff City. He ended his playing career at Hereford United, becoming player-coach in 1998 and subsequently returned to Wolves as a youth team coach.

He joined Cheltenham Town as assistant manager in the summer of 2004, working alongside manager John Ward, who he had met through his time at Wolves where Ward had been assistant manager. When Ward left the club to join Carlisle United in October 2007, Downing stepped in as caretaker manager, before being given the position on a full time basis on 2 November 2007. He left the club by mutual consent on 13 September 2008.