CLF (the Concurrent Logical Framework) is a language for specifying and reasoning about concurrent systems. Its most significant feature is the first-class representation of concurrent executions as monadic expressions. We illustrate the representation techniques available within CLF by applying them to an asynchronous pi-calculus with correspondence assertions, including its dynamic semantics, safety criterion, and a type system with latent effects due to Gordon and Jeffrey.

Abstract. We formalise the pi-calculus using the nominal datatype package, a package based on ideas from the nominal logic by Pitts et al., and demonstrate an implementation in Isabelle/HOL. The purpose is to derive powerful induction rules for the semantics in order to conduct machine checkable proofs, closely following the intuitive arguments found in manual proofs. In this way we have covered many of the standard theorems of bisimulation equivalence and congruence, both late and early, and both strong and weak in a unison manner. We thus provide one of the most extensive formalisations of a process calculus ever done inside a theorem prover. A significant gain in our formulation is that agents are identified up to alpha-equivalence, thereby greatly reducing the arguments about bound names. This is a normal strategy for manual proofs about the pi-calculus, but that kind of hand waving has previously been difficult to incorporate smoothly in an interactive theorem prover. We show how the nominal logic formalism and its support in Isabelle accomplishes this and thus significantly reduces the tedium of conducting completely formal proofs. This improves on previous work using weak higher order abstract syntax since we do not need extra assumptions to filter out exotic terms and can keep all arguments within a familiar first-order logic.

This paper presents a method for coding pi-calculus in the COQ proof assistant, in order to use this environment to formalize properties of the pi-calculus. This method consists in making a syntactic discrimination between free names (then called parameters) and bound names (then called variables) of the processes, so that implicit renamings of bound names are avoided in the substitution operation. This technique has been used by J.McKinna and R.Pollack in an extensive study of PTS [5]. We use this coding here to prove subject reduction property for a type system of a monadic pi-calculus.

Abstract. We present a coinductive proof system for bisimilarity in transition systems specifiable in the de Simone SOS format. Our coinduction is incremental, in that it allows building incrementally an a priori unknown bisimulation, and pattern-based, in that it works on equalities of process patterns (i.e., universally quantified equations of process terms containing process variables), thus taking advantage of equational reasoning in a “circular ” manner, inside coinductive proof loops. The proof system has been formalized and proved sound in Isabelle/HOL. 1

� Goal: To learn how to properly use references when writing. � We will talk a lot about references and a little about how to write a technical paper. � Assignment: Write a two page paper on a technical topic of your own choice. You must use (at least) 3 different types of references. Deadline: 20/9. Institutionen för informationsteknologi | www.it.uu.se Why use references? What is a reference? Informationsteknologi � To give credit (to the original discovery) � To relieve the writer from (some) responsibility � To lead the reader to a source (for more details) � To show the evolution in a field Informationsteknologi Any material where the reader can find more information on the subject. Two main types of references Archival: Books, journals, proceedings... Non-archival: Internet, lecture notes, oral