Date	Speaker	Title
January 18	Jared Corduan Dartmouth College	Recursion theoretic analysis of the Nash Williams Barrier Partition Theorem
January 25	Jared Corduan Dartmouth College	$\omega^{\omega}$ is a partition ordinal
February 8	Jared Corduan Dartmouth College	A partition result of Erdos and Milner
February 15	No seminar this week	Penelope Maddy will be giving the joint math/philosophy colloqium at 4
February 22	Mia Minnes Cornell University	Title: Complexity of Tree Questions based on their Presentations Abstract: 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.
February 29	Asher Kach University of Connecticut	Title: Computable Embeddings of Computable Linear Orders Abstract: 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 non-scattered linear order having no computable presentation into which the rationals computably embed; and the existence of a non-well-ordered 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.
March 7	Brooke Andersen Dartmouth College	Sets that fail to be $D$-complete
March 21	Francois Dorais Cornell University	Class Forcing in Small Universes

Last Updated: December 12, 2008

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