**Scope**

State-based dynamical systems as found throughout computing science are traditionally described as transition systems or certain kinds of automata. During the last decade, it has become increasingly clear that such systems can be captured uniformly as so-called ``coalgebras'' (which are the formal dual of algebras). Coalgebra is beginning to develop into a field of its own, with its own proof-methods (involving bisimulations and invariants). This workshop will be devoted to both an introduction to basic coalgebraic notions and techniques, and also to some recent advances in the theory of coalgebras.

We are looking for participants to this informal workshop on both the theory and the use of coalgebras in computer science. Depending on the reactions, the workshop will consist of one or two days, preceding the ETAPS conference (28-29 March 1998).

The scope of the meeting includes the following themes:

- the theory of coalgebras (including set theoretic and categorical approaches);
- coalgebras as computational and semantical models (for programming languages, dynamic systems, etc.);
- coalgebras in (functional, object-oriented, concurrent) programming;
- coalgebras and data types;
- (coinductive) definition and proof principles for coalgebras (with bisimulations or invariants);
- coalgebras and (hidden-sorted) algebras;
- coalgebraic specification and verification;
- coalgebras and (modal) logic

Participants are encouraged to suggest extensions to the list above.

**Organization**: Bart Jacobs
(Nijmegen), Horst Reichel (Dresden), Jan
Rutten (CWI, Amsterdam) and
Larry Moss
(Bloomington, IN).

**Saturday, March 28th, 14.00 - 17.30:**

- James Worrell: Toposes of coalgebras and hidden algebras
- John Power and Hiroshi Watanabe: An axiomatics for categories of coalgebras
- D. Pavlovic: Guarded induction on final coalgebras
- Andrea Corradini, Martin Grosse-Rhode, and Reiko Heckel: Structured transition systems as lax coalgebras
- Horst Reichel: Dialgebraic Logic

**Sunday, March 29th, 9.00 - 12.30:**

- Paul Caspi and Marc Pouzet: A co-iterative characterization of synchronous stream functions
- Alberto Pardo: Monadic Corecursion---Definition, Fusion Laws, and Applications---
- Erik de Vink: On a functor for probabilistic bisimulation preserving weak pullbacks
- Luis Monteiro: Semantic domains based on sets with families of equivalences
- Jan Rutten: Relators, bimodules, and behavioural distances

**Sunday, March 29th, 14.00 - 17.30:**

- Grigore Rosu: A Birkhoff-like axiomatizability result for hidden algebra
- H. Peter Gumm and Tobias Schroder: Covarieties and complete covarieties
- Dmitri Schamschurko: Modeling Process Calculuses with PVS
- Alexander Kurz: Specifying coalgebras with modal logic
- Bart Jacobs: Reasoning about classes in object-oriented languages (this talk contains a demo)

**Location**

The workshop will take place at the Faculty of Sciences, Campo Grande, see the relevant ETAPS page for more information.

**Publication**

A special volume of the ENTCS series (Electronic Lecture Notes in Theoretical Computer Science) contains the proceedings of the meeting. Hard copies of this volume are available at the meeting. At a later stage, a special issue of TCS (Theoretical Computer Science) is foreseen, with selected contributions from the earlier ENTCS volume.

**Registration**

Registration for the CMCS workshop takes place via the ETAPS registration page.

Some references on the subject can be found in some of the papers on our homepages (Bart Jacobs and Jan Rutten). In particular, a tutorial is available, containing an introduction to coalgebras and coinduction (with many references). It has been published in the Bulletin of the European Association for Theoretical Computer Science 62 (1997), p.222-259.