computational complexity

, Volume 23, Issue 1, pp 85–98 | Cite as

ReachFewL = ReachUL

  • Brady Garvin
  • Derrick Stolee
  • Raghunath Tewari
  • N. V. Vinodchandran
Article

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.

Keywords

Log-space complexity unambiguous computations graph reachability 

Subject classification

68Q05 68Q10 68Q15 68Q17 

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Copyright information

© Springer Basel 2012

Authors and Affiliations

  • Brady Garvin
    • 1
  • Derrick Stolee
    • 1
  • Raghunath Tewari
    • 2
  • N. V. Vinodchandran
    • 1
  1. 1.Department of Computer Science and EngineeringUniversity of Nebraska-LincolnLincolnUSA
  2. 2.Department of Computer Science and EngineeringIndian Institute of Technology, KharagpurKharagpurIndia

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