A series of rule governed state transitions whose rules can be altered.

There are numerous competing definitions of computation. Along with the initial definition provided here, the following three definitions are often encountered:
  1. Rule governed state transitions
  2. Discrete rule governed state transitions
  3. Rule governed state transitions between interpretable states
The difficulties with these definitions can be summarized as follows:
  1. Admits all physical systems into the class of computational systems, making the definition somewhat vacuous
  2. Excludes all forms of analog computation, perhaps including the sorts of processing taking place in the brain.
  3. Necessitates accepting all computational systems as representational systems. In other words, there is no computation without representation on this definition.
Chris Eliasmith