Discrete mathematics/Finite state automata

From testwiki
Revision as of 22:14, 12 October 2007 by imported>Mike's bot account (re-categorization for Subject: pages)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

Formally, a Deterministc Finite Automaton is a 5-tuple D=(Q,Σ,δ,s,F) where:

Q is the set of all states.
Σ is the alphabet being considered.
δ is the set of transitions, including exactly one transition per element of the alphabet per state.
s is the single starting state.
F is the set of all accepting states.

Similarly, the formal definition of a Nondeterministic Finite Automaton is a 5-tuple N=(Q,Σ,δ,s,F) where:

Q is the set of all states.
Σ is the alphabet being considered.
δ is the set of transitions, with epsilon transitions and any number of transitions for any particular input on every state.
s is the single starting state.
F is the set of all accepting states.

Note that for both a NFA and a DFA, s is not a set of states. Rather, it is a single state, as neither can begin at more than one state. However, a NFA can achieve similar function by adding a new starting state and epsilon-transitioning to all desired starting states.

The difference between a DFA and an NFA being the delta-transitions are allowed to contain epsilon-jumps(transitions on no input), unions of transitions on the same input, and no transition for any elements in the alphabet.

For any NFA N, there exists a DFA D such that L(N)=L(D)