Why aims at being a verification conditions generator (VCG) back-end for other verification tools. It provides a powerful input language including higher-order functions, polymorphism, references, arrays and exceptions. It generates proof obligations for many systems: the proof assistants Coq, PVS, Isabelle/HOL, HOL 4, HOL Light, Mizar and the decision procedures Simplify, Alt-Ergo, Yices, CVC Lite and haRVey.

This package contains examples of programs verified using Why.