Logic Seminar
Bill Howard
UIC
The "ordinal of predicativity" and the theory of constructions
Abstract: An ordinal is said to be predicative if it measures the strength of a
predicative formal system of analysis (ie., a system based on predicative
definitions of sets of natural numbers and proofs). Kreisel, Schuette and
Feferman proposed in the 1960s that a certain ordinal (Gamma_0) is the least
upper bound of the predicative ordinals. This is open to controversy (see FOM
last spring: Weaver vs. others). I shall examine the situation from the
viewpoint of the theory of constructions.
We will meet for lunch at 12 noon
Tuesday April 3, 2007 at 3:00 PM in SEO 427