
 State transition system  Open Encyclopedia (Site not responding. Last check: 20071102) 
  In a state transition system, transitions do not form a function, but a relation between the states, and therefore, there may be zero or more than one transition out of a given state, with the same input. 
  State transition systems with a finite number of states and transitions can be represented as directed graphs. 
  Formally, an unlabelled state transition system is a tuple (S, →) where S is a set (of states) and → ⊆ S × S is a binary relation over S (of transitions.) If p,q ∈ S, (p,q) ∈ → is usually written as p → q. 
 openencyclopedia.com /State_transition_system (356 words) 
