# Welcome to New York Logic

Welcome to New York Logic!

Mar 27 Friday Mar 28 Saturday Mar 29 Sunday Mar 30 Monday Mar 31 Tuesday Apr 1 Wednesday Apr 2 Thursday
Model theory seminarMar 27, 201512:30 pm

Models of PAApr 1, 20154:50 pm

go to the Calendar

## Upcoming talks and events:

Set theory seminarMonday, March 30, 20155:00 pmGC 3309

# Harrington’s Principle and remarkable cardinals

University of Münster

It is open whether $\Pi^1_1$ determinacy implies the existence of $0^{\#}$ in 3rd order arithmetic, call it $Z_3$. We compute the large cardinal strength of $Z_3$ plus “there is a real $x$ such that every $x$-admissible is an $L$-cardinal.” This is joint work with Yong Cheng.

Computational Logic SeminarTuesday, March 31, 20152:00 pmGraduate Center, 6421

# NEXP-completeness and Universal Hardness Results for Justification Logic

We provide a lower complexity bound for the satisfiability problem of a multi-agent justification logic, establishing that there are certain NEXP-complete multi-agent justification logics with interactions. We then use a simple modification of the corresponding reduction to prove that satisfiability for all multi-agent justification logics in a general class we consider is $Sigma_2^p$-hard — given certain reasonable conditions. Our methods improve on these required conditions for the same lower bound for the single-agent justification logics, proven by Buss and Kuznets in 2009, thus answering one of their open questions.

http://arxiv.org/abs/1503.00362

Models of PAWednesday, April 1, 20154:50 pmGC 6300

# The undecidability of lattice-ordered groups II

GC CUNY

In this talk I will discuss conjugacy in the automorphism group of the rationals as a linearly ordered set, and then show that the integers, together with addition and multiplication, can be interpreted in Aut(Q), and thus that the theory of Aut(Q) is undecidable.

Friday, April 3, 2015
Friday, April 10, 2015

# Spring break

CUNY’s spring vacation is April 3-11, 2015. Therefore, no seminars will meet at the Graduate Center on April 3, nor on April 10.

CUNY Logic WorkshopFriday, April 17, 20152:00 pmGC 6417

# Title TBA

Florida Atlantic University
Kolchin seminar in Differential AlgebraFriday, April 24, 201510:15 amGC 5382

# TBA

University of Pennsylvania
Kolchin seminar in Differential AlgebraFriday, May 1, 201510:15 amGC 5382

# TBA

McMaster University
Model theory seminarFriday, May 8, 201512:30 pmGC 6417

# Title TBA

George Washington University
Kolchin seminar in Differential AlgebraFriday, May 22, 201510:15 amGC 5382

# Title TBA

University of Illinois at Urbana-Champaign
Model theory seminarFriday, May 22, 201512:30 pmGC 6417

# TBA

University of California, Los Angeles