Welcome to New York Logic

Welcome to New York Logic!

Aug 29 Saturday Aug 30 Sunday Aug 31 Monday Sep 1 Tuesday Sep 2 Wednesday Sep 3 Thursday Sep 4 Friday

Models of PASep 2, 20156:15 pm

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Upcoming talks and events:

Models of PAWednesday, September 2, 20156:15 pmGC 4214-03
Athar Abdul-Quader

Enayat Models

The CUNY Graduate Center

Simpson proved that every countable model of PA has an expansion (to PA*) that is pointwise definable. The natural question, then, is if every countable model has an expansion to PA* in which no new elements are defined. Enayat proved this is false by showing the existence of many models that are not pointwise definable, but become so upon addition of any undefinable class. Inspired by this, I have begun thinking about which models have this property. I will describe some models with this property (and some without) and talk about my search for a non-trivial such model (I will also explain what I mean by “non-trivial” here).

Model theory seminarFriday, September 11, 201512:30 pmGC 6417
Russell Miller

Degree spectra of real closed fields

City University of New York

The degree spectrum of a countable structure is the set of all Turing degrees of isomorphic copies of that structure. This topic has been widely studied in computable model theory. Here we examine the possible degree spectra of real closed fields, finding them to offer far more complexity than the related theory of algebraically closed fields. The co-author of this project, Victor Ocasio Gonzalez, showed in his dissertation that, for every linear order L, there exists a real closed field whose spectrum is the pre-image under jump of the spectrum of L. We add further results, distinguishing the cases of archimedean and non-archimedean real closed fields, and splitting the latter into two subcases based on the existence of a least multiplicative class of positive nonstandard elements. If such a class exists, then finiteness in the field is always decidable, but the case with no such class proves more interesting.

CUNY Logic WorkshopFriday, September 18, 20152:00 pmGC 6417
Victoria Gitman

Ehrenfeucht principles in set theory

The City University of New York
Set theory seminarModel theory seminarCUNY Logic WorkshopFriday, September 25, 2015

No talks on September 25

On Friday, September 25, CUNY will follow a Tuesday schedule. Therefore, no logic seminars will meet that day.

CUNY Logic WorkshopFriday, October 16, 20152:00 pmGC 6417
Alexei Kolesnikov

Title TBA

Towson University
CUNY Logic WorkshopFriday, November 13, 20152:00 pmGC 6417
Philipp Hieronymi

Title TBA

University of Illinois Urbana-Champaign
Set theory seminarModel theory seminarCUNY Logic WorkshopFriday, November 27, 2015

No talks November 27

There will be no talks on November 27, the day after Thanksgiving.

CUNY Logic WorkshopFriday, December 11, 20152:00 pmGC 6417
Dana Bartosova

Title TBA

Universidade de São Paulo