# Process Algebra with Four-Valued Logic

## Alban Ponse

(University of Amsterdam)

Three and four-valued logic arise naturally in descriptions of data types with error/exceptions and divergencies. We take this observation as a point of departure, and propose a combination of a fragment of four-valued logic and process algebra. This fragment can easily be extended to a truth-functionally complete logic (for instance by adding a definedness predicate), and is geared to a simple relation with process algebra via the guarded command. We present an operational semantics in SOS-style, and a completeness result for ACP with conditionals and four-valued logic.

Joint work with Jan A. Bergstra (University of Amsterdam and Utrecht University).

**Friday 14th November 1997, 14:30**

Seminar Room 322

Department of Computer Science