Under the hypothesis that NP does not have p-measure 0 (roughly, that NP contains more than a negligible subset of exponential time), it is show n that there is a language that is polynomial-time Turing complete (``Cook complete''), but not polynomial-time many-one complete (``Karp-Levin complete''), for NP. This conclusion, widely believed to be true, is not known to follow from P<>NP or other traditional complexitytheoretic hypotheses. Evidence is presented that ``NP does not have p-measure 0'' is a reasonable hypothesis with many credible consequences. Additional such consequences proven here include the separation of many truth-table reducibilities in NP (e.g., k queries versus k+1 queries), the class separation E<>NE, and the existence of NP search problems that are not reducible to the corresponding decision problems.
Disciplines
Theory and Algorithms
AbstractUnder the hypothesis that NP does not have p-measure 0 roughly, that NP contains more than a negligible subset of exponential time, it is show n that there is a language that is P T -complete Cook complete", but not P m -complete Karp-Levin complete", for NP. This conclusion, widely believed to be true, is not known to follow from P 6 = NP or other traditional complexity-theoretic hypotheses.Evidence is presented that NP does not have p-measure 0" is a reasonable hypothesis with many credible consequences. Additional such consequences proven here include the separation of many truthtable reducibilities in NP e.g., k queries versus k +1 queries, the class separation E 6 = NE, and the existence of NP search problems that are not reducible to the corresponding decision problems.