A tighter upper bound for random MAX 2-SAT

  • Authors:
  • Xuelin Xu;Zongsheng Gao;Ke Xu

  • Affiliations:
  • LMIB & School of Mathematics and Systems Science, Beihang University, Beijing, 100191, PR China;LMIB & School of Mathematics and Systems Science, Beihang University, Beijing, 100191, PR China;State Key Laboratory of Software Development Environment, Beihang University, Beijing, 100191, PR China

  • Venue:
  • Information Processing Letters
  • Year:
  • 2011

Quantified Score

Hi-index 0.89

Visualization

Abstract

Given a conjunctive normal form F with n variables and m=cn 2-clauses, it is interesting to study the maximum number maxF of clauses satisfied by all the assignments of the variables (MAX 2-SAT). When c is sufficiently large, the upper bound of f(n,cn)@?E(maxF) of random MAX 2-SAT had been derived by the first-moment argument. In this paper, we provide a tighter upper bound (3/4)cn+g(c)cn also using the first-moment argument but correcting the error items for f(n,cn), and g(c)=(3/4)cos((1/3)xarccos((4ln2)/c-1))-3/8 when considering the @e^3 error item. Furthermore, we extrapolate the region of the validity of the first-moment method is c2.4094 by analyzing the higher order error items.