Mechanized Verification with Sharing

We consider software verification of imperative programs by theorem proving in higher-order separation logic. Of particular interest are the difficulties of encoding and reasoning about sharing and aliasing in pointer-based data structures. Both of these are difficulties for reasoning in separation logic because they rely, fundamentally, on non-separate heaps. We show how sharing can be achieved while preserving abstraction using mechanized reasoning about fractional permissions in Hoare type theory.