Computer Science Department
School of Computer Science, Carnegie Mellon University


Deciding Quantifier-Free Presburger Formulas using
Finite Instantiation based on Parameterized Solution Bounds

Sanjit A. Seshia, Randal E. Bryant

December 2003

Keywords: Presburger arithmetic, Boolean satisfiability, separation (difference-bound) constraints, solution bounds, finite instantiation, decision procedures, theorem proving

Given a formula φ in quantifier-free Presburger arithmetic, it is well known that, if there is a satisfying solution to φ, there is one whose size, measured in bits, is polynomially bounded in the size of φ. In this paper, we consider a special class of quantifier-free Presburger formulas in which most linear constraints are separation (difference-bound) constraints, and the non-separation constraints are sparse. This class has been observed to commonly occur in software verification problems. We derive a new solution bound in terms of parameters characterizing the sparseness of linear constraints and the number of non-separation constraints, in addition to traditional measures of formula size. In particular, the number of bits needed per integer variable is linear in the number of non-separation constraints and logarithmic in the number and size of non-zero coefficients in them, but is otherwise independent of the total number of linear constraints in the formula. The derived bound can be used in a decision procedure based on instantiating integer variables over a finite domain and translating the input quantifier-free Presburger formula to an equi-satisfiable Boolean formula, which is then checked using a Boolean satisfiability (SAT) solver. We present empirical evidence indicating that this method can greatly outperform other decision procedures.

19 pages

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