On the isomorphism problem for decision trees and decision lists

  • Authors:
  • Vikraman Arvind;Johannes Köbler;Sebastian Kuhnert;Gaurav Rattan;Yadu Vasudev

  • Affiliations:
  • The Institute of Mathematical Sciences, Chennai, India;Institut für Informatik, Humboldt-Universität zu Berlin, Germany;Institut für Informatik, Humboldt-Universität zu Berlin, Germany;The Institute of Mathematical Sciences, Chennai, India;The Institute of Mathematical Sciences, Chennai, India

  • Venue:
  • FCT'13 Proceedings of the 19th international conference on Fundamentals of Computation Theory
  • Year:
  • 2013

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Abstract

We study the complexity of isomorphism testing for Boolean functions that are represented by decision trees or decision lists. Our results include a $2^{\sqrt{s}(\lg s)^{O(1)}}$ time algorithm for isomorphism testing of decision trees of size s. Additionally, we show: · Isomorphism testing of rank-1 decision trees is complete for logspace. · For r≥2, isomorphism testing for rank-r decision trees is polynomial-time equivalent to Graph Isomorphism. As a consequence we obtain a ${2^{\sqrt{s}(\lg s)^{O(1)}}}$ time algorithm for isomorphism testing of decision trees of size s. · The isomorphism problem for decision lists admits a Schaefer-type dichotomy: depending on the class of base functions, the isomorphism problem is either in polynomial time, or equivalent to Graph Isomorphism, or coNP-hard.