A detailed model of a random access computation over an ab stract domain is presented and the existence of an NP complete problem is proven under broad conditions which unify Cook s theorem and recent results in the real number model by Blum Shub and Smale

The e ect of query order on NP completeness is investigated A sequence D D Dk of decision problems is de ned to be sequentially complete for NP if each Di NP and every problem in NP can be decided in polynomial time with one query to each of D Dk in this order It is shown that if NP contains a language that is p generic in the sense of Ambos Spies Fleischhack and Huwig then for every integer k ...

Nonuniformity is a central concept in computational complexity with powerful connections to circuit complexity and randomness. Nonuniform reductions have been used to study the isomorphism conjecture for NP and completeness for larger complexity classes. We study the power of nonuniform reductions for NP-completeness, obtaining both separations and upper bounds for nonuniform completeness vs un...

We consider the complexity of the traveling tournament problem, which is a well-known benchmark problem in tournament timetabling. The problem was supposed to be computationally hard ever since its proposal in 2001. Recently, the first NP-completeness proof has been given for the variant of the problem were no constraints on the number of consecutive home games or away games of a team are consi...

In this note we give an easier proof of the known result that the car sequencing problem is NP-hard, and point out that it is NP-hard in the strong sense. We show that a previous claim of NP-completeness is incorrect, and instead we give a sufficient condition of membership of NP. We also provide a pseudo-polynomial algorithm for a special case.

Given a nite two player game with common payoos (i.e., the players have completely common interests), we show that the problem of determining whether there exists a joint strategy whose expected joint payoo is at least (1; 1) is NP-complete.

We prove that deciding whether a given input word contains as subsequence every possible permutation of integers {1, 2, . . . , n} is coNP-complete. The coNP-completeness holds even when given the guarantee that the input word contains as subsequences all of length n−1 sequences over the same set of integers. We also show NP-completeness of a related problem of Partially Non-crossing Perfect Ma...