Moore machine

In the theory of computation, a Moore machine is a finite-state machine whose current output values are determined only by its current state. This is in contrast to a Mealy machine, whose output values are determined both by its current state and by the values of its inputs. Like other finite state machines, in Moore machines, the input typically influences the next state. Thus the input may indirectly influence subsequent outputs, but not the current or immediate output. The Moore machine is named after Edward F. Moore, who presented the concept in a 1956 paper, “Gedanken-experiments on Sequential Machines.” A Moore machine can be defined as a 6-tuple consisting of the following: A finite set of states A start state (also called initial state) which is an element of A finite set called the input alphabet A finite set called the output alphabet A transition function mapping a state and the input alphabet to the next state An output function mapping each state to the output alphabet A Moore machine can be regarded as a restricted type of finite-state transducer. A state transition table is a table listing all the triples in the transition relation . The state diagram for a Moore machine, or Moore diagram, is a diagram state diagram that associates an output value with each state. As Moore and Mealy machines are both types of finite-state machines, they are equally expressive: either type can be used to parse a regular language. The difference between Moore machines and Mealy machines is that in the latter, the output of a transition is determined by the combination of current state and current input ( as the domain of ), as opposed to just the current state ( as the domain of ). When represented as a state diagram, for a Moore machine, each node (state) is labeled with an output value; for a Mealy machine, each arc (transition) is labeled with an output value. Every Moore machine is equivalent to the Mealy machine with the same states and transitions and the output function , which takes each state-input pair and yields , where is 's output function and is 's transition function.