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On the Complexity of Pointer Arithmetic in Separation Logic

  • James BrotherstonEmail author
  • Max Kanovich
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 11275)

Abstract

We investigate the complexity consequences of adding pointer arithmetic to separation logic. Specifically, we study an extension of the points-to fragment of symbolic-heap separation logic with sets of simple “difference constraints” of the form \(x \le y + k\), where x and y are pointer variables and k is an integer offset. This extension can be considered a practically minimal language for separation logic with pointer arithmetic.

Most significantly, we find that, even for this minimal language, polynomial-time decidability is already impossible: satisfiability becomes \(\mathsf {NP}\)-complete, while quantifier-free entailment becomes \(\mathsf {coNP}\)-complete and quantified entailment becomes \(\varPi ^P_2\)-complete (where \(\varPi ^P_2\) is the second class in the polynomial-time hierarchy).

However, the language does satisfy the small model property, meaning that any satisfiable formula has a model, and any invalid entailment has a countermodel, of polynomial size, whereas this property fails when richer forms of arithmetical constraints are permitted.

Keywords

Separation logic Pointer arithmetic Complexity 

Notes

Acknowledgements

Many thanks to Josh Berdine and Nikos Gorogiannis for a number of illuminating discussions on pointer arithmetic, and to our anonymous reviewers for their comments, which have helped us to improve the presentation of this paper.

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Copyright information

© Springer Nature Switzerland AG 2018

Authors and Affiliations

  1. 1.University College LondonLondonUK
  2. 2.National Research University Higher School of EconomicsMoscowRussian Federation

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