Science Fair Project Encyclopedia
Alternating finite automaton
In automata theory, an alternating finite automaton (AFA) is a non-deterministic finite automaton whose transitions are divided into existential and universal transitions. Let A be an alternating automaton.
- For a transition
, A nondeterministically chooses to switch the state to either q1 or q2, reading a.
- For a transition
, A moves to q1 and q2, reading a.
Note that due to the universal quantification a run is represented by a run tree. A accepts a word w, if there exists a run tree on w such that every path ends in an accepting state.
A basic theorem tells that any AFA is equivalent to an non-deterministic finite automaton (NFA) by performing a similar kind of powerset construction as it is used for the transformation of a NFA to a deterministic finite automaton (DFA). This construction converts an AFA with k states to a NFA with up to 2k states.
09-23-2007 01:00:40
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details


