(2+ f(n))-SAT and Its Properties

  • Authors:
  • Xiaotie Deng;Chan H. Lee;Yunlei Zhao;Hong Zhu

  • Affiliations:
  • -;-;-;-

  • Venue:
  • COCOON '02 Proceedings of the 8th Annual International Conference on Computing and Combinatorics
  • Year:
  • 2002

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Abstract

Consider a formula which contains n variables and m clauses with the form 驴 = 驴驴 驴 驴驴, where 驴驴 is an instance of 2-SAT which contains m驴 2-clauses and 驴驴 is an instance of 3-SAT which contains m驴 3-clauses. 驴 is an instance of (2 + f(n))-SAT if (m驴/m驴 + m驴) 驴 f(n). We prove that (2 + f(n))-SAT is in P if f(n) = O(log n/n驴), and in NPC if f(n) =1/(n驴-驴) (驴驴 : 0 n)k/n驴)-SAT (k = 2), for natural problems in NP - NPC - P (denoted as NPI) with respect to this (2 + f(n))-SAT model. We prove that the restricted version of it is not in NPC under the assumption P 驴 NP. Actually it is indeed in NPI under some stronger but plausible assumption, specifically, the Exponential-Time Hypothesis (ETH) which was introduced by Impagliazzo and Paturi.