Exact cover

Exact cover

In mathematics, given a set "X" and a collection mathcal{S} of subsets of "X", an exact cover mathcal{S}^* is a subcollection of mathcal{S} such that every element in "X" is contained in "exactly one" set in mathcal{S}^*. An exact cover is a kind of cover.

In computer science, the exact cover problem is a decision problem to find an exact cover or else determine none exists. The exact cover problem is NP-complete [

The N queens problem is an example of an exact cover problem.

See also

* Constraint satisfaction problem
* Dancing Links
* Difference_map_algorithm
* Hitting set
* Karp's 21 NP-complete problems
* Knuth's Algorithm X
* List of NP-complete problems

References

* cite web
last = Dahlke
first = K
title = Exact cover
work = Math Reference Project
url = http://www.mathreference.com/lan-cx-np,excov.html
accessdate = 2008-06-21


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