Editing Decision problem (section)

== Complete problems ==

{{main|Complete problem}}

Decision problems can be ordered according to [[many-one reduction|many-one reducibility]] and related to feasible reductions such as [[polynomial-time reduction]]s. A decision problem ''P'' is said to be ''[[complete problem|complete]]'' for a set of decision problems ''S'' if ''P'' is a member of ''S'' and every problem in ''S'' can be reduced to ''P''. Complete decision problems are used in [[computational complexity theory]] to characterize [[complexity class]]es of decision problems. For example, the [[Boolean satisfiability problem]] is complete for the class [[NP (complexity)|NP]] of decision problems under polynomial-time reducibility.