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In computational complexity theory and computability theory, a counting problem is a type of computational problem. If ''R'' is a search problem then : is the corresponding counting function and : denotes the corresponding counting problem. Note that ''cR'' is a search problem while #''R'' is a decision problem, however ''cR'' can be ''C'' Cook reduced to #''R'' (for appropriate ''C'') using a binary search (the reason #''R'' is defined the way it is, rather than being the graph of ''cR'', is to make this binary search possible). ==Counting complexity class== If ''NC'' is a complexity class associated with non-deterministic machines then ''#C'' = is the set of counting problems associated with each search problem in ''NC''. In particular, #P is the class of counting problems associated with NP search problems. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Counting problem (complexity)」の詳細全文を読む スポンサード リンク
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