Winter 2008
Seminar this term will meet Fridays at 2:00 pm in Kemeny 008.
Date  Speaker  Title 

Jan 18 
Jared Corduan
Dartmouth College

Recursion theoretic analysis of the Nash Williams Barrier Partition Theorem 
Jan 25 
Jared Corduan
Dartmouth College

$\omega^{\omega}$ is a partition ordinal 
Feb 8 
Jared Corduan
Dartmouth College

A partition result of Erdos and Milner 
Feb 15  No seminar this week  Penelope Maddy will be giving a joint math/philosophy colloquium at 4.  
Feb 22 
Mia Minnes
Cornell University

Complexity of tree questions based on their presentations How hard is it to tell if two trees are isomorphic? We use isomorphism invariants to place this question on the analytical hierarchy for different classes of trees (namely, recursive partial order trees, automatic partial order trees, and automatic successor trees). This is joint work with Bakhadyr Khoussainov. 
Feb 29 
Asher Kach
University of Connecticut

Computable embeddings of computable linear orders In this talk, we'll discuss what the existence of a classical embedding between computable linear orders implies about the complexity (from a computability viewpoint) of such embeddings. Specifically, we'll demonstrate the existence of a nonscattered linear order having no computable presentation into which the rationals computably embed; and the existence of a nonwellordered linear order having no computable presentation into which the negative integers computably embed. As time permits, we'll sharpen these results by increasing the minimal complexity of any embedding and by demonstrating the minimality (in terms of rank) of the examples presented. This work is joint with Joe Miller and Reed Solomon. 
Mar 7 
Brooke Andersen
Dartmouth College

Sets that fail to be $D$complete 
Mar 21 
Francois Dorais
Cornell University

Class forcing in small universes 