Nontriviality for exponential time w.r.t. weak reducibilities

  • Authors:
  • Klaus Ambos-Spies;Timur Bakibayev

  • Affiliations:
  • University of Heidelberg, Institut für Informatik, Im Neuenheimer Feld 294, D-69120 Heidelberg, Germany;Al-Farabi Kazakh National University, 71 Al-Farabi ave., Almaty 050038, Kazakhstan

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2013

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Abstract

A set A is nontrivial for the linear exponential time class E=DTIME(2^l^i^n) if A@?E and the sets from E which can be reduced to A are not from a single level DTIME(2^k^n) of the linear exponential hierarchy. Similarly, a set A is nontrivial for the polynomial exponential time class EXP=DTIME(2^p^o^l^y) if A@?EXP and the sets from EXP which can be reduced to A are not from a single level DTIME(2^n^^^k) of the polynomial exponential hierarchy (see [2]). Here we compare the strength of the nontriviality notions with respect to the underlying reducibilities where we consider the polynomial-time variants of many-one, bounded truth-table, truth-table, and Turing reducibilities. Surprisingly, the results obtained for E and EXP differ. While the above reducibilities yield a proper hierarchy of nontriviality notions for E, nontriviality for EXP under many-one reducibility and truth-table reducibility coincides.