Southern Wisconsin Logic Colloquium

Logic Picnic on May 9

This semester's logic picnic will be held on Saturday, May 9, on the south shore of Devil's Lake. All UW logic faculty, staff and students (and their spouses/significant others) are invited.

The picnic is being organized by Turbo Ho, Reese Johnston and Paul Tveite. Please email Turbo ( to let us know how many will be in your party and whether you can give or need a ride. We will leave from the Van Vleck loading dock at noon; please do not drive directly to Devil's Lake unless your car is full so that everyone can get a ride.

As usual, brats, burgers, vegetarian alternatives and drinks will be provided courtesy of the UW logic faculty. Please bring a salad or dessert to share.

SWLC Schedule

Refreshments will be served in the 9th floor lounge a half hour before talks. Please check the schedule below. All talks will be in 901 Van Vleck Hall unless stated otherwise.

Date Time Speaker Title Cookies,
dinner, etc.
Tuesday, April 28 4:00 p.m. Iván Ongay Valverde, UW 1-dense sets of reals (specialty exam, see abstract) cookies/juice
at 3:30
Tuesday, May 5 4:00 p.m. Ethan McCarthy, UW TBA (specialty exam) cookies/juice
at 3:30
Tuesday, September 8 4:00 p.m. TBA TBA cookies/juice
at 3:30
Tuesday, September 15 4:00 p.m. TBA TBA cookies/juice
at 3:30
Tuesday, September 22 4:00 p.m. TBA TBA cookies/juice
at 3:30
Tuesday, September 29 4:00 p.m. Jerry Keisler, UW TBA cookies/juice
at 3:30/
dinner at 6
Tuesday, October 6 4:00 p.m. Henry Townser, University of Pennsylvania, Philadelphia TBA cookies/juice
at 3:30/
dinner at 6

Math 873 - Fall 2015 - Topics in Logic - Medvedev and Muchnik Degrees

Instructor: Rutger Kuyper

Prerequisites: Math 770, and Math 773 or concurrent registration in Math 773

Time and Place: MWF 13:20-14:10

Textbook: none

Course Description: The Medvedev and Muchnik degrees are extensions of the Turing degrees studied in computability theory. Both of these structures also have nice substructures, namely, the degrees of the so-called effectively closed sets, which form an analogue to the computably enumerable degrees studied in the Turing degrees.

We will discuss various aspects of these structures. In particular, we will cover the following topics, including their necessary prerequisites:

Math 975 - Reading Seminar in Logic

Our reading seminar is meeting on Thursdays at 3:30 in B325 (spring) and B119 (fall) Van Vleck Hall.

Abstracts of talks

Ongay Valverde's talk:1-dense sets of reals

Cantor prooved that any two countable dense linear order without endpoints are isomorphic. If we change countable to ℵ1, the result cannot be true, so our best possible way to generalize it is to look at ℵ1-dense sets of reals. Sierpiński showed that, assuming CH, there are two ℵ1-dense sets of reals that are not isomorphic. Baumgartner proved that it is consistent to have CH fail and all ℵ1-dense sets of reals isomorphic to each other. We will talk about these results and other generalizations and related work.

Prepared by Steffen Lempp (">