Welcome to New York Logic!
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Upcoming talks and events:
Boolean algebras of elementary substructures
In his 1976 paper Haim Gaifman proved that for every set I, every model M of PA has an elementary end extension N such that Lt(N/M) is isomorphic to P(I). I will present a proof.
Structurability and countable Borel equivalence relations
The dynamical and descriptive set theoretic complexity of a countable Borel equivalence relation E can often be understood in terms of the kinds of countable first order structures which are compatible with E in a suitable sense. In this talk I will make this suitable sense precise by discussing the notion of Borel structurability. I will also discuss some recent joint work with Brandon Seward in which we show that the equivalence relation generated by the free part of the translation action of a countable group G on its powerset is structurably-universal among equivalence relations generated by free Borel actions of G.
The Consistency of Peano Arithmetic
In 1936, only a few years after the incompleteness theorems were proved, Gentzen proved the consistency of Peano arithmetic by using transfinite induction up to the ordinal epsilon_0. I will give a short proof of the result, based on on the simplification introduced by Schutte, and discuss some of the consequences.
New England Recursion & Definability Seminar, Spring 2014
The spring NERDS meeting this year will take place on Sunday, March 30, 2014, from 11 am until 4 pm, at Olin College in Needham, MA, fifteen miles west of Boston. Directions are available here. Further details will be posted when available, including speakers and titles of talks. NERDS is a one-day meeting on computability theory which takes place twice a year, at assorted sites throughout New England.
