Computational Logic Seminar
Tuesday, October 22, 2013 2:00 pm Graduate Center, rm, 3209
Speaker: Melvin Fitting Lehman College – CUNY Graduate Center
Title: Justification Logic Semantics: A Little New, but Mostly Old
Possible world semantics was introduced for justification logic in 2005. Initially it was for the Logic of Proofs, but it quickly extended to “nearby” logics, and more slowly to a wider family. Eight years is a long time, and by now people may be generally familiar with the ideas without having gone through any of the details. I will try to remedy that.
Set theory seminar
Friday, October 25, 2013 10:00 am
Speaker: Erin Carmody The CUNY Graduate Center
Title: Killing Inaccessible Cardinals Softly
I shall introduce the killing-them-softly phenomenon among large cardinals by showing how it works for inaccessible and Mahlo cardinals. A large cardinal is killed softly whenever, by forcing, one of its large cardinal properties is destroyed while as many as possible weaker large cardinal properties, below this one, are preserved. I shall also explore the various degrees of inaccessibility and show Mahlo cardinals are alpha-hyperbeta-inaccessible and beyond.
Model theory seminar
Friday, October 25, 2013 12:30 pm
Speaker: Alf Dolich The City University of New York
CUNY Logic Workshop
Friday, October 25, 2013 2:00 pm GC 6417
Speaker: Jim Schmerl University of Connecticut
Title: Automorphism Groups of Countable, Recursively Saturated Models of Peano Arithmetic
It is still unknown whether there are nonisomorphic countable recursively saturated models M and N whose automorphism groups Aut(M) and Aut(N) are isomorphic. I will discuss what has happenednover the last 20 years towards showing that such models do not exist, including some very recent results.
Set theory seminar
Friday, November 1, 2013 10:00 am GC 6417
Speaker: Karel Hrbacek City College of New York, CUNY
Title: Some problems motivated by nonstandard set theory
Nonstandard set theory enriches the usual set theory by a unary “standardness” predicate. Investigations of its foundations raise a number of questions that can be formulated in ZFC or GB and appear open. I will discuss several such problems concerning elementary embeddings, ultraproducts, ultrafilters and large cardinals.