Formal Philosophy

Logic at Columbia University

Category: Events

Ramanujam: Reasoning in games that change during play

by Yang Liu

Reasoning in games that change during play
R. Ramanujam (Institute of Mathematical Sciences, India)
4:00 – 6:00 PM, Friday, June 2, 2014
Room 4421, CUNY GC

Abstract. We consider large games, in which the number of players is so large that outcomes are determined not by strategy profiles, but by distributions. In the model we study, a society player monitors choice distributions and intervenes periodically, leading to game changes. Rationality of individual players and that of the society player are mutually interdependent in such games. We discuss stability issues, and mention applications to infrastructure problems.

Pacuit: Knowledge-Theoretic Aspects of Strategic Voting

by Yang Liu

Knowledge-Theoretic Aspects of Strategic Voting
Eric Pacuit (University of Maryland)
4:15 – 6:15 PM, Friday, May 9, 2014
Room 3309, CUNY GC

Abstract. It has long been noted that a voter can sometimes achieve a preferred election outcome by misrepresenting his or her actual preferences. In fact, the classic Gibbard-Sattherthwaite Theorem shows that under very mild conditions, every voting method that is not a dictatorship is susceptible to manipulation by a single voter. One standard response to this important theorem is to note that a voter must possess information about the other voters’ preferences in order for the voter to decide to vote strategically. This seems to limit the “applicability” of the theorem. In this talk, I will survey some recent literature that aims at making this observation precise. This includes models of voting under uncertainty (about other voters’ preferences) and models that take into account how voters may response to poll information.

Egan: Three Grades of Self-Involvement

by Ignacio Ojea

Three Grades of Self-Involvement
Andy Egan (Rutgers University)
4:10-6:00 PM, April 3rd, 2014
716 Philosophy Hall, Columbia University

Reception will follow

Ojea: Evaluation Games for Many Valued Logics

by Ignacio Ojea

Evaluation Games for many valued logics
Ignacio Ojea (Columbia University)
4:15 PM, March 28th, 2014
Room 3305, CUNY Graduate Center

Abstract.  Evaluation Games for classical logic are well known. Following early applications of games in model theory, by Ehrenfeucht and Fraisse, Hintikka and Parikh independently proposed a game-theoretic approach as a way of defining the classical semantics. A great deal of the game theoretic approach has been more recently studied by van Bentham. The original idea was to define the truth-value of a wff, in a given model, in terms of the existence of a strategy for one of the players (the “Verifier” and “Falsifier”) in a certain two-person game. These games can be also viewed in terms of pay-offs. Recently I suggested a natural extension of these games to the case of many valued logics, where the notion of a Nash equilibrium plays a crucial role.

Georgatos: Topologic – old and new results

by Yang Liu

Topologic: old and new results
Konstantinos Georgatos (CUNY)
4:15 PM, Friday, March 21, 2014
Room 3305, CUNY GC

Abstract. In 1992, Moss and Parikh introduced Toplogic an epistemic modal logic whose semanticas are based on subsets. Since then, research on this logic and it many extensions has been going strong. I will survey most of these results in the first part of this talk. On the second part, I will present how topologic can form a basis for the formalization of belief change operators, such as update, conditionals and contraction. Arbitrary nestings and iterations of such operators are easily automatized which is not the case in other studies of belief change in object language.

Ijjas: Cosmology at the Crossroads

by Yang Liu

Cosmology at the Crossroads
Anna Ijjas (Princeton)
4:10 – 6:00pm PM , March 3, 2014
201D Philosophy Hall, Columbia University

Abstract. Thirty years of inflation have greatly changed modern cosmological thinking. Most importantly, inflation provides a paradigm for the generation of primordial density fluctuations seeding the structure of our universe, by stretching quantum fluctuations to cosmological distances. However, the physics governing the evolution of the very early universe before nucleosynthesis remains a challenge for modern theoretical cosmology. In this talk, I will begin by reviewing inflationary cosmology and discussing the reasons why most cosmologists today consider it to be the leading paradigm. Then, I will turn to the flaws of inflationary thinking and present possible ways out.