(definition)
Definition: (1) a structure providing an easily verified bound on the optimal value of an optimization problem. Typically used in the analysis of an approximation algorithm to prove the performance guarantee. (2) a mismatch of two symbols of string y at a distance of d is a "witness" to the fact that in no subject y could occur twice at a distance of exactly d positions (equivalently, that d cannot be a period of y).
See also certificate.
Note: From Algorithms and Theory of Computation Handbook, pages 13-17 and 34-18, Copyright © 1999 by CRC Press LLC. Appearing in the Dictionary of Computer Science, Engineering and Technology, Copyright © 2000 CRC Press LLC.
Author: CRC-A
If you have suggestions, corrections, or comments, please get in touch with Paul E. Black.
Entry modified 17 December 2004.
HTML page formatted Mon Sep 11 09:46:09 2006.
Cite this as:
Algorithms and Theory of Computation Handbook, CRC Press LLC, 1999, "witness", in
Dictionary of Algorithms and Data
Structures [online], Paul E. Black, ed.,
U.S. National Institute of
Standards and Technology. 17 December 2004. (accessed TODAY)
Available from: http://www.nist.gov/dads/HTML/witness.html