Logic Seminar
Steffen Lempp (UW) - The theory of the Ziegler degrees
Event Details
Date
Tuesday, September 8, 2026
Time
4 p.m.
Location
901 Van Vleck Hall
Description
Abstract - The Ziegler degrees were introduced to characterize definability in group theory. In joitn work with Jacobsen-Grocott and I. Scott, I had shown that the first order-theory of the Ziegler degrees (as a partial order) is undecidable. In joint work with Downey and I. Scott, we have now improved this result, showing that the theory of the Ziegler degrees is bi-interpretable with true second-order arithmetic.
Cost
Free
Accessibility
We value inclusion and access for all participants and are pleased to provide reasonable accommodations for this event. Please call 608-263-3054 or email mathfrontdesk@math.wisc.edu to make a disability-related accommodation request. Reasonable effort will be made to support your request.