EECS20N: Signals and Systems


The input and output alphabets have a special element called the stuttering element, typically denoted absent, such that for any sStates,

update(s, absent) = (s, absent).

When the input symbol is the stuttering element, the state does not change, and the output symbol is the stuttering element. In other words, although there is a reaction, no progress is made.

The stuttering element will prove useful when we synchronously compose state machines because it will allow one machine to react by changing state while another machine stutters, remaining in the same state.