Anti-unification algorithms and their applications in program analysis

A term t is called a template of terms t 1 and t 2 iff t 1∈=∈tη 1 and t 2∈= ∈tη 2, for some substitutions η 1 and η 2. A template t of t 1 and t 2 is called the most specific iff for any template t' of t 1 and t 2 there exists a substitution ξ such that t∈=∈t'ξ. The anti-unification proble...

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Bibliographic Details
Main Authors: Bulychev, P, Kostylev, E, Zakharov, V
Format: Conference item
Published: Springer 2010
Description
Summary:A term t is called a template of terms t 1 and t 2 iff t 1∈=∈tη 1 and t 2∈= ∈tη 2, for some substitutions η 1 and η 2. A template t of t 1 and t 2 is called the most specific iff for any template t' of t 1 and t 2 there exists a substitution ξ such that t∈=∈t'ξ. The anti-unification problem is that of computing the most specific template of two given terms. This problem is dual to the well-known unification problem, which is the computing of the most general instance of terms. Unification is used extensively in automatic theorem proving and logic programming. We believe that anti-unification algorithms may have wide applications in program analysis. In this paper we present an efficient algorithm for computing the most specific templates of terms represented by labelled directed acyclic graphs and estimate the complexity of the anti-unification problem. We also describe techniques for invariant generation and software clone detection based on the concepts of the most specific templates and anti-unification. © 2010 Springer Berlin Heidelberg.