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The Complexity of Counting Functions with Easy Decision Version

机译:简单决策版本计数功能的复杂性

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We investigate the complexity of counting problems that belong to the complexity class #P and have an easy decision version. These problems constitute the class #PE which has some well-known representatives such as #PERFECT MATCHINGS, #DNF-SAT, and NONNEGATIVE PERMANENT. An important property of these problems is that they are all #P-complete, in the Cook sense, while they cannot be #P-complete in the Karp sense unless P = NP. We study these problems in respect to the complexity class TotP, which contains functions that count the number of all paths of a PNTM. We first compare TotP to #P and #PE and show that FP is contained in TotP is contained in #PE is contained in #P and that the inclusions are proper unless P = NP. We then show that several natural #PE problems — including the ones mentioned above — belong to TotP. Moreover, we prove that TotP is exactly the Karp closure of self-reducible functions of #PE. Therefore, all these problems share a remarkable structural property: for each of them there exists a polynomial-time nondeterministic Turing machine which has as many computation paths as the output value.
机译:我们调查计算属于复杂性类#p的问题的复杂性,并且具有简单的决策版本。这些问题构成了班级#pe,它有一些着名的代表,如#perfect匹配,#dnf-sat和非负永久性。这些问题的一个重要属性是它们都是#p-temply,在厨师的意义上,除非p = np,否则它们不能在karp sense中排名第一。我们在复杂性类TOTP上研究这些问题,其中包含计算PNTM所有路径的函数。我们首先比较TOTP到#P和#PE,并显示FP包含在TOTP中,其中#pe包含在#p中,除非p = np,夹杂物是正确的。然后,我们表明了几个自然的#pe问题 - 包括上面提到的问题 - 属于Totp。此外,我们证明了TOTP正好是#PE的自我可重复函数的KARP闭合。因此,所有这些问题都具有显着的结构特性:对于它们中的每一个,存在具有作为输出值的计算路径的多项式非术语定义机器。

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