Seminar: A. Slinko 2012-06-18

Speaker:     Arkadii Slinko
Affiliation: The University of Auckland
Title:       Geometric properties of voting rules
Date:        Monday, 18 Jun 2012
Time:        4:00 pm
Location:    Room 6115, Owen Glenn Building

Each axiom of voting rules considered in Economics and Political Science reflects some notion of fairness, e.g., unanimity requires that, if all voters vote for a certain candidate, this candidate should be elected; anonymity requires that it does not matter who submitted which ballot; monotonicity requires that, if support of the winner of the election grows, she should remain the winner of the election.

In a completely different vein we investigate the geometric properties of voting rules. We define a graph on the set of all elections as vertices and colour them  in a such a way that two vertices have the same colour if and only if the corresponding elections have the same winner. We determine for which classic social choice rules the monochromatic components are connected, convex, etc.

This is a work in progress in co-authorship with Edith Elkind, Svetlana Obraztsova, Piotr Faliszewski.

Seminar: P. Girard 2012-05-21

Speaker:     Patrick Girard
Affiliation: The University of Auckland
Title:       Logical dynamics of belief change in the community
Date:        Monday, 21 May 2012
Time:        4:00 pm
Location:    Room 6115, Owen Glenn Building

In this paper we explore the relationship between norms of belief revision that may be adopted by members of a community and the resulting dynamic properties of the distribution of beliefs across that community. We show that  at a qualitative level many aspects of social belief change  can be obtained from a very simplistic model, which we call `threshold influence’. In particular, we focus on the question of what makes the beliefs of a community stable under various dynamical situations. Besides, we  consider refinements and alternatives to the `threshold’ model. The most significant alternative is to move to consideration of plausibility judgements rather than mere beliefs. We show first that some such change is mandated by difficult problems with belief-based dynamics related to the need to decide on an order in which different beliefs are considered. Secondly, we show that the resulting plausibility-based account results in a dynamical system that is non-deterministic at the level of beliefs. Nonetheless, the plausibility-based account lacks certain intuitively desirable features, such as the preservation of the transitivity.

Seminar: P. Girard 2012-05-07

Speaker:     Patrick Girard
Affiliation: The University of Auckland
Title:       Ceteris paribus reasoning and preferences
Date:        Monday, 7 May 2012
Time:        4:00 pm
Location:    Room 6115, Owen Glenn Building

Ceteris Paribus clauses in reasoning are used to allow for defeaters of norms, rules or laws, such as in von Wright’s example “I prefer my raincoat over my umbrella, everything else being equal”. I offer an analysis in which sets of formulas S, embedded in modal operators, provide necessary and sufficient conditions for things to be equal in ceteris paribus clauses. I’ll talk about how ceteris paribus preferences can be formalised and discuss questions that arise with the formalisation, and propose some solutions.

Seminar: A. Slinko 2012-03-26

Speaker:     Arkadii Slinko
Affiliation: The University of Auckland
Title:       MMP review: what are the issues and what are the options?
Date:        Monday, 26 Mar 2012
Time:        4:00 pm
Location:    Room 6115, Owen Glenn Building

In this talk I will outline the issues under consideration in the current review of the MMP voting system and outline the major options that can be chosen. I will try to explain the rational and major trade-offs made in the design of hybrid systems like MMP. From this point we will start a discussion on particular issues. This will hopefully start the process of preparation of a submission to the Electoral Commission on behalf of the Centre.

Workshop on Game Theory, Epistemic Logic, and related topics

From Mamoru Kaneko, an external affiliate of CMSS:

We will have a small informal workshop on epistemic logic, game theory, and related topics.  This time, emphasized topics are: Epistemic, cognitive aspects of game theory, and human behavior in social context. Methods are: philosophical, theoretical, experimental and simulation studies.

See the workshop website for more details. Submission deadline for abstracts is 25 May 2012 and the workshop is 27-30 August.