Welcome to New York Logic!

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## Upcoming talks and events:

# Local Ramsey theory: an abstract approach

This talk is about an abstract version of the notion of semi-selective co-ideal for subsets of a topological Ramsey space. This version is useful to characterize the corresponding generalization of the local Ramsey property in “topological terms”. We will also talk about forcing notions related to this abstract version of semi-selectivity, generalizing those related to Ellentuck’s space, and we will comment on some applications.

# Topological Ramsey spaces and Fraïssé structures

There seems to be a natural relationship between topological Ramsey spaces and Fraïssé classes of finite structures. In fact, for some Fraïssé classes satisfying the Ramsey property, it is possible to define a topological Ramsey space such that the Fraïssé limit of the class is essentially an element of the space. We will talk about examples of this phenomenon, describe the general case to some extent, and comment about how this could be understood as a abstract tool to classify Fraïssé structures.

# An alternate proof of the Halpern-Läuchli Theorem in one dimension

I will present a new proof of the strong subtree version of the Halpern-Läuchli Theorem, using an ultrafilter on $\omega$. The one dimensional Halpern-Läuchli Theorem states that for every finite partition of an infinite, finitely branching tree $T$, there is one piece $P$ of the partition and a strong subtree $S$ of $T$ such that $S \subseteq P$. This will cover the one dimensional case, with hopes that the proof can be extended to cover a product of trees.

# Computable algebra: a personal perspective

I will give a brief overview of some of my recent research in the field of Computable Algebra, emphasizing connections between Computability Theory and Algebra. Some of the topics that I hope to cover include Artinian and Euclidean rings, as well as infinite dimensional vector spaces. There will be no proofs, just statements of theorems along with discussions on their logical and algebraic significance.

# No seminars on Sept. 26 or October 3

CUNY will have holidays on two consecutive Fridays, September 26 and October 3, 2014, so the Logic Workshop and other seminars will not meet on those days.

# NERDS

The Autumn 2014 meeting of NERDS, the New England Recursion & Definability Seminar, will take place on Saturday, October 18 at Assumption College, in Worcester, MA, beginning at 11 a.m. The principal organizers are Brooke Andersen, Damir Dzhafarov, and Reed Solomon. Further details, including specific speakers and abstracts, will be posted here as they become available.