An NP-complete number-theoretic problem

  • Authors:
  • Eitan M. Gurari;Oscar H. Ibarra

  • Affiliations:
  • -;-

  • Venue:
  • STOC '78 Proceedings of the tenth annual ACM symposium on Theory of computing
  • Year:
  • 1978

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Abstract

Systems of nonlinear equations of the form D: A&ymarc; &equil; &sgr;marc;.(x), where A is an m×n matrix of rational constants and &ymarc; &equil; (Y1,...,yn), &sgr;(x) &equil; (&sgr;1(x),..., &sgr;m (x)) are column vectors are considered. Each &sgr;i(x) is of the form ri(x) or @@@@ri(x)@@@@, where ri(x) is a rational function of x with rational coefficients. It is shown that the problem of determining for a given system D whether there exists a nonnegative integral solution (y1,...,yn,X) satisfying D is decidable. In fact, the problem is NP-complete when restricted to systems D in which the maximum degree of the polynomials defining the &sgr;i(x)'s is bounded by some fixed polynomial in the length of the representation of D. Some recent results connecting Diophantine equations and counter machines are briefly mentioned.