# Gruszczyńsk: Methods of constructing points from regions of space

Rafał Gruszczyńsk (Nicolaus Copernicus University, Toruń) will give an informal, non-colloquium talk this Friday, Nov. 21, at 2pm, in the seminar room (Philosophy 716). The title of the talk is “Methods of constructing points from regions of space”. Everybody is invited. The talk should be of special interest to colleagues and students working in logic, ontology, the philosophy of mathematics, and the philosophy of space and time.

# Ramanujam: Reasoning in games that change during play

CUNY SEMINAR IN LOGIC, PROBABILITY, AND GAMES
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

CUNY SEMINAR IN LOGIC, PROBABILITY, AND GAMES
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.

# The Inaugural Meeting of the Columbia-CUNY Joint Workshop in Logic, Probability, and Games

The Value of Ignorance and Objective Probabilities
Haim Gaifman (Columbia)
2:00-3:00 PM, October 18th, 2013
Rm. 4419, CUNY GC

Abstract. There are many cases in which knowledge has negative value and a rational agent may be willing to pay for not being informed. Such cases can be classified into those which are essentially of the single-agent kind and those where the negative value of information derives from social interactions, the existence of certain institution, as well as from legal considerations. In the single-agent case the standard examples involve situations in which knowing has in itself a value, besides its instrumental cognitive value for achieving goals. But in certain puzzling examples knowing is still a cognitive instrument and yet it seems to be an obstacle. Some of these cases touch on foundational issues concerning the meaning of objective probabilities. Ellsberg’s paradox involves an example of this kind. I shall focus on some of these problems in the later part of the talk.

Knowledge is Power, and so is Communication
Rohit Parikh (CUNY)
3:00-4:00 PM, October 18th, 2013
Rm. 4419, CUNY GC

Abstract. The BDI theory says that people’s actions are influenced by two factors, what they believe and what they want. Thus we can influence people’s actions by what we choose to tell them or by the knowledge that we withhold. Shakespeare’s Beatrice-Benedick case in Much Ado about Nothing is an old example. Currently we often use Kripke structures to represent knowledge (and belief). So we will address the following issues: a) How can we bring about a state of knowledge, represented by a Kripke structure, not only about facts, but also about the knowledge of others, among a group of agents? b) What kind of a theory of action under uncertainty can we use to predict how people will act under various states of knowledge? c) How can A say something credible to B when their interests (their payoff matrices) are in partial conflict? When can B trust A not to lie about this matter?

# Protopopescu: Discovering Knowability

CUNY Computational Logic Seminar
September 4, Time 2:00 – 4:00 PM, Room 3309.
Abstract: We provide a semantic analysis of the well-known knowability paradox stemming from the Church-Fitch observation that the meaningful knowability principle all truths are knowable, when expressed as a bi-modal principle $F \to \diamond KF$yields an unacceptable omniscience property all truths are known. We offer an alternative semantic proof of this fact independent of the Church-Fitch argument. This shows that the knowability paradox is not intrinsically related to the Church-Fitch proof, nor to the Moore sentence upon which it relies, but rather to the knowability principle itself. Further, we show that, from a verifiability perspective, the knowability principle fails in the classical logic setting because it is missing the explicit incorporation of a hidden assumption of stability: `the proposition in question does not change from true to false in the process of discovery.’ Once stability is taken into account, the resulting stable knowability principle and its nuanced versions more accurately represent verification-based knowability and do not yield omniscience.