This Week in Logic at CUNY:

*Computational Logic Seminar*

Time 2:00 – 4:00 PM, April 17, 2012, Room 3209.

Speaker: Çağıl Taşdemir (Graduate Center)

Title: The Power of Knowledge in Games

Abstract: We propose a theory of the interaction between knowledge and

games. Epistemic game theory is a well developed subject but there is

also a need for a theory of how some agents can affect the outcome of

a game by affecting the knowledge which other agents have and thereby

affecting their actions.

We concentrate on games of incomplete or imperfect information, and

study how conservative, moderate, or aggressive players might play

such games. We provide models for the behavior of a knowledge

manipulator who seeks to manipulate the knowledge states of active

players in order to affect their moves and to maximize her own payoff

even while she herself remains inactive.

This is joint work with Rohit Parikh (The Graduate Center and Brooklyn

College) and Andreas Witzel (NYU).

*Set Theory Seminar*

Friday, April 20, 2012 10:00 am GC 6417

Mr. Alexander Rapp (Ph.D. Program in Mathematics, Graduate Center of CUNY)

Cohen forcing adds a Souslin Tree

Abstract. It will be shown, using an argument of Todorcevic, that

Cohen forcing adds a Souslin tree. The result is due to Shelah.

*Model Theory Seminar*

Friday, April 20, 2012 12:30 pm GC 6417

Professor John Baldwin (University of Illinois at Chicago)

Axiomatic Set Theory and L_{omega_1,omega}

Abstract. In the late 1960’s model theory and axiomatic set theory

seemed to be inevitably intertwined. The fundamental notions of first

order stability theory are absolute. We describe the role of this fact

in the development of first order model theory independent from set

theory since the 1970’s. The role of extensions of ZFC in infinitary

logic is muddled. Important results are proved using weak extensions

of ZFC; the use is not in general proved essential. We expound the

following proof-scheme: 1) Prove an infinitary sentence is consistent

with ZFC. 2) Prove there is a model of set theory for which this

sentence is absolute. 3) Deduce the property it expresses is provable

in ZFC. We will describe how this technique implies the following

recent result: Theorem (Shelah) Let phi be a sentence of

L_{omega_1,omega}. a) If ‘algebraic closure’ fails exchange on models

of phi then phi has many models in aleph_1. b) If phi is

pseudo-minimal then it has model in the continuum. Here `algebraic

closure’ and `pseudo-minimal’ are modifications of classical notions

appropriate for the context.

*Logic Workshop*

Friday, April 20, 2012 2:00 pm GC 6417

Professor Ivo Herzog (Ohio State University)

Diophantine Sets of Representations

Abstract. Let k be a field of characteristic 0 and L the special

linear Lie algebra sl(2,k). The Lie algebra L acts by derivations on

the ring k[x,y] of polynomials in two variables. This L-representation

admits a direct sum decomposition of k[x,y] into the subspaces

k[x,y]_n of homogeneous polynomials of total degree n. We will prove

that if phi(v) is a positive-primitive formula in one free variable,

and k is recursively presented, then the subset { n | phi(k[x,y]_n) =

0} of the natural numbers is recursive.

This is joint work with S. L’Innocente.

Next Week in Logic at CUNY:

– – – – Monday, Apr 23, 2012 – – – –

Models of Peano Arithmetic

Monday, April 23, 2012 7:00 pm Room 4214-03

Mr. Thomas Ferguson (Ph.D. Program in Philosophy, Graduate Center of CUNY)

Isomorphic + and nonisomorphic x

– – – – Tuesday, Apr 24, 2012 – – – –

– – – – Wednesday, Apr 25, 2012 – – – –

– – – – Thursday, Apr 26, 2012 – – – –

– – – – Friday, Apr 27, 2012 – – – –

Set Theory Seminar

Friday, April 27, 2012 10:00 am GC 6417

Professor Thomas Johnstone (NYC College of Technology (CUNY))

The Definability of the Ground Model in Forcing Extensions

Logic Workshop

Friday, April 27, 2012 2:00 pm GC 6417

Professor Chris Miller (The Ohio State University)

Towards a foundation for tame control theory.

Abstract. Mathematical control theory is the area of

application-oriented mathematics that deals with the basic principles

underlying the analysis and design of control systems. There is a

natural division of control systems into two main types: discrete and

continuous. I will discuss how model-theoretic methods or points of

view might contribute to more abstract or foundational aspects of

continuous control via the study of expansions of o-minimal structures

on the real field by trajectories of definable vector fields.

– – – – Other Logic News – – – –

– – – – Web Site – – – –

The majority of this information, including an interactive calendar of

future events, can be found at our website:

http://nylogic.org/Calendar

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