(definition)

**Definition:**
A *finite state machine* whose *transition function* maps inputs symbols and *states* to a (possibly empty) set of *next states*. The transition function also may map the null symbol (no input symbol needed) and states to next states.

**Also known as** NFA, nondeterministic finite automaton.

**See also**
*deterministic finite state machine*.

*Note:
Any such machine may be converted to a deterministic finite state machine, although the number of states may increase by an exponential amount.
*

* Thanks to Thorsten Jens (thojens@gmx.de) and Yaacov Yesha (yayesha@cs.umbc.edu) for correcting this entry. 17 January 2001.*

Author: PEB

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Entry modified 17 December 2004.

HTML page formatted Mon Feb 2 13:10:40 2015.

Cite this as:

Paul E. Black, "nondeterministic finite state machine", in
*Dictionary of Algorithms and Data Structures* [online], Vreda Pieterse and Paul E. Black, eds. 17 December 2004. (accessed TODAY)
Available from: http://www.nist.gov/dads/HTML/nondetermFiniteStateMach.html