19 March 2012
Amsterdam, The Netherlands
COIN, or Coalgebra in the Netherlands, is a seminar taking place
alternating at the Radboud University Nijmegen and the CWI in
Amsterdam. The aim of COIN is to bring together coalgebra researchers
from various locations in the Netherlands, and share current results
and questions in the world of coalgebra. We welcome presentations on
any subject related to coalgebra.
The next COIN meeting is scheduled for Monday, 19 March 2012, at the
CWI, in room L120. The schedule is as follows:
13:30 - 14:15 Georgiana Caltais (Reykjavik University Iceland)
Final Semantics for Decorated Traces
14:15 - 15:00 Tomasz Brengos (Warsaw University of Technology)
Weak bisimulations for coalgebras over ordered functors
15:15 - 16:00 Clemens Kupke (University of Oxford)
Dualities and minimal automata
COIN is coordinated by Marcello Bonsangue (Leiden University/CWI), Bart
Jacobs (Radboud Universiteit Nijmegen), and Jan Rutten (CWI/Radboud
Universiteit Nijmegen), and its website can be found at
http://homepages.cwi.nl/~winter/coin.html
Abstracts
=========
Georgiana Caltais (Reykjavik University Iceland)
Final Semantics for Decorated Traces
------------------------------------
In concurrency theory, various semantic equivalences on labelled
transition systems are based on traces enriched or decorated with some
additional observations. They are generally referred to as decorated
traces, and examples include ready, failure, trace and complete trace
equivalence. In this talk we shall apply the generalized powerset
construction in order to give a coalgebraic presentation of decorated
trace semantics. This will allow us to provide a uniform notion of
canonical, minimal representatives for the various decorated trace
equivalences, in terms of final Moore automata. As a consequence, we
shall see how proofs of decorated trace equivalence can be given by
coinduction, using different types of (Moore-) bisimulation, which is
helpful for automation.
This is joint work with Filippo Bonchi (LIP-ENS Lyon), Marcello
Bonsangue (Leiden University/CWI), Jan Rutten (CWI/Radboud University
Nijmegen), and Alexandra Silva (Radboud University Nijmegen, CWI).
Tomasz Brengos (Warsaw University of Technology)
Weak bisimulations for coalgebras over ordered functors
-------------------------------------------------------
The aim of this talk is to introduce a coalgebraic setting in which it is
possible to generalize and compare the two known approaches to weak
bisimulation for labelled transition systems. To be more precise, for an
ordered functor F and a class of F-coalgebras satisfying some additional
properties we define a coalgebraic saturator which will serve as the base
for two approaches to generalizing weak bisimulation. Although the two
ways of defining weak bisimulation for LTS are known to be equivalent, we
will show that in the general setting of ordered functors they do not
always have to coincide. We will give sufficient conditions for them to
match and present interesting examples of functors and coalgebras where
they differ.
Finally, we will talk about restrictions of the generalization and
problems for further research.
Clemens Kupke (CWI)
Dualities and minimal automata
------------------------------
In my talk I am going to describe how dualities between categories of
finite automata (coalgebras) and algebras can be used in order to obtain
Brzozowski-like minimisation constructions for different types of
(deterministic) automata. In particular, I will focus on linear weighted
and probabilistic automata. This is joint work with Nick Bezhanishvili
and Prakash Panangaden.