Review: Hoare triples, wp, sp from previous lecture03.

Big Picture of VCG

We will first consider programs without loops.

Normal Form of Loop-Free Programs

Compositional VCG

Forward VCG

Backward VCG

We next look at proof rules for loops, assuming loop invariants are given.

Hoare Logic Rule for Loops

We next look at a program semantics that has explicit error conditions, and that gives nice rules for weakest preconditions.

Assert and Error Conditions

Practical Aspects of VCG