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ReachFewL = ReachUL

Abstract

We show that two complexity classes introduced about two decades ago are unconditionally equal. ReachUL is the class of problems decided by nondeterministic log-space machines which on every input have at most one computation path from the start configuration to any other configuration. ReachFewL, a natural generalization of ReachUL, is the class of problems decided by nondeterministic log-space machines which on every input have at most polynomially many computation paths from the start configuration to any other configuration. We show that ReachFewL = ReachUL.

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Correspondence to N. V. Vinodchandran.

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Garvin, B., Stolee, D., Tewari, R. et al. ReachFewL = ReachUL. comput. complex. 23, 85–98 (2014). https://doi.org/10.1007/s00037-012-0050-8

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Keywords

  • Log-space complexity
  • unambiguous computations
  • graph reachability

Subject classification

  • 68Q05
  • 68Q10
  • 68Q15
  • 68Q17