This paper compares Propositional Dynamic Logic of Non-Regular Programs and Fixpoint Logic with Chop. It identifies a fragment of the latter which is equiexpressive to the former. This relationship transfers several decidability and complexity results between the two logics.

We present a proof of completeness of hyper-resolution based on the fixpoint semantics of disjunctive logic programs. This shows that hyperresolution can be studied from the point of view of logic programming.

These notes give an introduction to the theory of the modal μ-calculus and other modal fixpoint logics. ∗Institute for Logic, Language and Computation, University of Amsterdam, Science Park 904, NL–1098XH Amsterdam. E-mail: [email protected].

We have already proposed a process algebra μLOTOS as a mathematical framework to synthesize a process from a number of (incomplete) specifications, in which requirements for the process do not have to be completely determined. It is guaranteed that the synthesized process satisfies all the given specifications, if they are consistent. For example, μLOTOS is useful for incremental design. The ad...

s Axiom sets and their extensions are viewed as functions from the set of formulas in the language, to a set of four truth-values t,f, s for undefined, and k for contradiction. Such functions form a lattice with 'contains less information' as the partial order and 'combination of several sources of knowledge' as the l.u.b. operation We demonstrate the relevance of this approach by giving concis...