Complete problems for deterministic polynomial time

  • Authors:
  • Neil D. Jones;William T. Laaser

  • Affiliations:
  • -;-

  • Venue:
  • STOC '74 Proceedings of the sixth annual ACM symposium on Theory of computing
  • Year:
  • 1974

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Abstract

The results of Cook and Karp ([K], [C]) aroused considerable interest for at least two reasons. First, the answer to a long-standing open question which had seemed peculiar to automata theory—whether deterministic and nondeterministic polynomial-time-bounded Turing machines are equivalent in power—was seen to be exactly equivalent to determining whether any of several familiar combinatorial problems can be solved by polynomial-time algorithms. Second, the existence of complete problems for NP1 made it possible to replace an entire class of questions by a question about a single representative.Thus all of these combinatorial and automata-theoretic problems were essentially restatements of a single problem, such as: can satisfiability of a propositional formula be decided in polynomial time. The main purpose of this paper is to introduce several problems which are complete for P, the class of languages recognizable in deterministic polynomial time. Any such language has the property that if it is recognizable in space logk(•), then every language in P is so recognizable. Thus a problem complete for P will serve to differentiate those sets in P which are not recognizable in logarithmic space from those which are, providing such differentiation is possible. A problem of this type was first presented by Cook in [C2], concerning solvable path systems.