University of Calgary

# Constructive Ordinals and the Consistency of PA

Submitted by Richard Zach on Mon, 03/17/2014 - 4:45pm

Today's the last of three lectures on Gentzen's second proof of the consistency of PA in my proof theory course.

a) Still looking for good resources on ordinal notations, esp., $<\epsilon_0$, especially around the question how one can "see" that they are well-ordered without mentioning that they are order-isomorphic to $\epsilon_0$  Takeuti has a discussion in his textbook, anything else?