Verified validation of lazy code motion

Partial Redundancy Elimination using Lazy Code Motion

Verified proof carrying code

Proof Carrying Code (PCC) is a technique to exclude safety errors in low level code. Instead of runtime tests, it statically checks a proof of safety (a certificate) attached to the code. To guarantee that PCC only accepts safe code, we formalise and verify it in Isabelle/HOL, an interactive theorem prover for higher order logic. In an abstract framework we identify key components and their int...

A Machine-Verified Code Generator

We consider the machine-supported verification of a code generator computing machine code from WHILE-programs, i.e. abstract syntax trees which may be obtained by a parser from programs of an imperative programming language. We motivate the representation of states developed for the verification, which is crucial for success, as the interpretation of tree-structured WHILE-programs differs signi...

ModelPlex: Verified Runtime Validation of Verified Cyber-Physical System Models

Formal verification and validation play a crucial role in making cyber-physical systems (CPS) safe. Formal methods make strong guarantees about the system behavior if accurate models of the system can be obtained, including models of the controller and of the physical dynamics. In CPS, models are essential; but any model we could possibly build necessarily deviates from the real world. If the r...

Code Optimizations for Lazy Evaluation

Implementations of lazy evaluation for non-strict functional languages usually involve the notion of a delayed representation of the value of an expression, which we call a thunk. We present several techniques for implementing thunks and formalize a class of optimizations that reduce both the space and time overhead of these techniques. The optimizations depend on a compile-time inferencing str...