Games in Logic, Language and Computation
Friday September 5, 2003
Academiegebouw, Senaatzaal
Broerstraat 5, Groningen
Last Update : 2003/08/28

The eighth edition of the workshop on Games in Logic, Language and
Computation (GLLC8) will be held on Friday September 5. For any
further information, email
Barteld Kooi, Hans van Ditmarsch or Gerben Blom.
The informal workshop series "Games in Logic, Language and Computation" focuses on the application of game theory in linguistics, logic and computer science, as well as on the (logical) foundations of game theory. Earlier meetings have taken place in Utrecht, Amsterdam, Nunspeet and Groningen.
The workshop is open to all interested. We would appreciate it if
all those who want to participate mail Barteld Kooi.


Sponsors

Department of Mathematics and Computing Science of the University of Groningen


Schedule

The abstracts are under the link of their title or follow this link.


Travel Information

Dutch train schedules for rail departure and arrival times throughout the
netherlands and international european destinations can be found at the Nederlandse Spoorwegen. There is
one important thing you should be carefull about in the train. This holds
for most trains bound for the north of the Netherlands. There is one part
of the train that is bound for Leeuwarden and one part of the train that is
bound for Groningen. These are two parts of the same train!! The train is
split into two parts in Zwolle.
To go from Groningen Central Station to the Academiegebouw exit the
Station main entrance (facing North), go a bit to the right and cross the
canal at the 20 meter high yellow matchbox (this happens to be the
Groninger Museum). Then walk straight on for about 10 minutes (H.N. Werkmanbrug,
Ubbo Emmiusstraat, Folkingestraat, Vismarkt, Stoeldraaiersstraat, Oude
Kijk in 't Jatstraat). Then turn right at the Academieplein. There you find
the Academiegebouw. A map of the city centre can be found here. You can
of course also take a taxi, which can also be found at the main entrance of
the station.


Previous GLLC's

GLLC 7 November 28 2002, Amsterdam, NL
GLLC 6 June 20 2002, Utrecht, NL
GLLC 5 December 12 2001, Amsterdam, NL
GLLC 4 November 21 2000, Groningen, NL.
GLLC 3 October 26 2000, Nunspeet, NL
GLLC 2 June 23 2000, Amsterdam, NL
GLLC/ILLC Workshop on Logic and Games November 1920 1999, Amsterdam, NL


Links

Tourist Office Groningen
Department of Mathematics
and Computing Science of the RuG
Department of Artificial
Intelligence of the RuG
Rijksuniversiteit Groningen


Titles and Abstracts.

Wiebe van der Hoek (University of Liverpool)
Agents that Know How to Play (Work with Wojcieck Jamroga)

In recent years there has been an increase of attention to
Alternating time Temporal Logic. Two semantics for it have been
proven to be equivalent, and attempts have been made to add an
epistemic component to it. In our talk we briefly sketch some
pitfalls that one can encounter by adding knowledge operators to
ATL. We then suggest a number of ways to overcome this.
This work is related to Barteld's work in the sense that it
is about 'Knowledge' and 'Change'. Since ATL is especially
attractive from a model checking perspective, and there
currently is some work on probabilistic model checkers, chanches
are that in the futurs ATL might also be enriched to reason
about 'Chanche'.

Hans van Ditmarsch (University of Otago)
Dynamic doxastic logic for defeasible belief revision

Degrees of belief can be modelled with a sphere semantics, where each of
some set of factual states (possible worlds) is associated with a
templated order, that corresponds to the default rule for that state. If a
distinguished outermost sphere is incorporated which corresponds to
definitely excluded states, knowledge can be modelled as well. For
interpreted and other multiagent systems, the system of spheres reduces to
the following: the agent's knowledge induces a partition on the set of
factual states, and default rules induce a templated order ('concentric
circles') on each class of the partition. In plain English: a bag of
onions, where an onion represents a state of knowledge, a peel a degree of
belief, and the innermost peel the most normal or minimal beliefs (in
belief revision the last is 'the to be revised belief set').
On such structures we can express both changes in knowledge and changes in
degrees of belief in a logical language that combines dynamic modal
operators for knowledge change with dynamic operators for belief revision.
As in 'normal' dynamic epistemic logic, such modal revision operators can
be seen as information state transformers, i.e., as binary relations
between information states. This may then result in a change of minimal
(preferred) states, as selected for most normal ('default') beliefs.
In my own PhD I described knowledge changes in the murder game Cluedo. I
did not extend my language to include beliefs and belief changes. Such
beliefs also depend on the distribution of states over epistemic classes
in models, and that can be addressed in probabilistic terms. Barteld Kooi
has described in detail how to reason about probabilities within the
precise setting of card game models as in Cluedo.

Boudewijn de Bruin (Universiteit van Amsterdam)
On Two Theorems About the Nash Equilibrium

Discussions with Barteld Kooi have been a source of
inspiration for me for the logical analysis of probability statements in
game theory. Paradigms of precision and subtlety, his analyses of
puzzles and paradoxes of probability are a trustworthy guide to a better
understanding of probabilistic reasoning.
I will discuss two results from Aumann&Brandenburger (1995): a
``preliminary observation'' about the epistemic assumptions of the
*pure* Nash equilibrium, and a real theorem about the *mixed* Nash
equilibrium. Logical analysis shows, I claim, that the distinction of
pure vs. mixed is not the most relevant one, but that rather the two
results provide characterizations of actions resp. beliefs. This means
that the real distinction is the one between *practical* and
*theoretical* rationality. And that is quite puzzling, or so I will
argue.

Marc Pauly (University of Liverpool)
Don't stick to the point, or: How not to aggregate individual judgements

Consider a political party which needs to agree on a party
programme, or an appointment committee at a university
which needs to decide which criteria the applicants satisfy.
In each case, a group needs to make a decision regarding
multiple propositions based on individual judgements. This
raises the question of how to aggregate individual judgements
into group judgements. It will be shown that the requirement
of logical consistency imposes very strong restrictions on the
possible decision making mechanisms.

Johan van Benthem (Stanford University, Universiteit van
Amsterdam)
Argumentation Games

Argumentation can be viewed as a game in many different ways.
Sometimes these are just ways of revamping standard logic.
But in this talk, we focus on the more procedural aspects of
argumentation in a game setting, looking at (a) pro and con
argument games (Prakken & Vreeswijk) which are basically
graph games, (b) the procedural component of Lorenzenstyle
dialogue games, and (c) some simple numerical games that
model weight of arguments, and various known effects, like
'halflife time' of arguments, and 'the success of success'.
References: "Logic in Games", ILLC, chapters 4 + 5, & some new material.

Francien Dechesne (Universiteit van Tilburg, Eindhoven University of
Technology)
IFlogic & pairs of existential second order sentences

In Hintikka's book ``The Principles of Mathematics Revisited'' (1996), it
is described how any IFsentence can be translated into an existential
second ordersentence (its truth condition), and how any e.s.o.sentence
is the truth condition of some IFsentence. An IFformula and its
e.s.o.translation are said to be equivalent. But this equivalence is only
a weak equivalence: two IFsentences can have the same truth condition,
while having different `falsityconditions'.
By the interpration of negation as role exchange in GTS, a falsity
condition of a formula is the truth condition of its negation. It can thus
be obtained in the same manner, hence also as an e.s.o.sentence. An
IFsentence is therefore strongly equivalent to a pair of
e.s.o.sentences. But conversely, not all pairs of e.s.o.sentences
correspond to an IFsentence. A recent note of John Burgess on Henkin
quantifiers answers the question which pairs of e.s.o.sentences do.

Benedikt Löwe(Universiteit van Amsterdam)
Determinacy for infinite perfect information games with more than
two players with preferences

We will discuss analogues of the GaleStewart theorem for
infinite nplayer games where the players have commonly known preferences.
The usual GaleStewart theory for two players and two players with a draw
will be recovered as a special case.


