Modular Specification and Verification of Delegation with SMT Solvers

Delegation is a very common programming idiom, whereby a task is carried out by a statically unknown part of the program. Delegation enhances the modularity and the extensibility of a program, and, for that reason, is the main ingredient of many important design patterns. Unfortunately, delegation complicates specification and verification: the programmer must either rely on unsuitably weak specifications imposed by behavioral subtyping, or compromise automation by resorting to higherorder logic. In this paper, we present an expressive specification and verification methodology, in which partial correctness reasoning about delegation can be carried out in first order logic, using automated SMT solvers.