The Midwest Computability
Seminar is a joint venture between the University of Chicago, the University
of Notre Dame, and the University of Wisconsin-Madison. It
meets once or twice per semester at the
University of Chicago, and is attended by faculty and students from these
universities and others
in the area. The seminar started in the
fall of 2008.
DATE: Thursday, March 16, 2017.
PLACE: Ryerson Hall 352 (the
Barn), The University of
1100 East 58th Street, Chicago, IL 60637.
- Greg Igusa - University of Notre Dame
- Jack Lutz - Iowa State University
- Sasha Melnikov - Massey University
- Reed Solomon - University of Connecticut
- 12:00 - 1:00: Lunch
- 1:00 - 1:50: Greg Igusa
- 2:00 - 2:50: Jack Lutz
- 3:40 - 4:30: Sasha Melnikov
- 4:40 - 5:30: Reed Solomon
- 6:00 Dinner at the Sit
Down, 1312 E. 53rd Street
Title: Monochromatic path decomposition
Abstract: In 1978, Rado published a theorem showing that, given any
n-coloring of pairs of integers, the integers can be partitioned by
a collection of n monochromatic paths through the integers, one for
each color. We consider this principle from the point of view of
effective combinatorics and reverse mathematics. Although the
principle bears a certain superficial resemblance to Ramsey's theorem
for pairs, the global requirement that the paths must partition
ω gives it a very different character.
The principle has a type-change between n=2 and n>2: When
restricted to a finite set, the principle remains true for n=2,
but is false for n>2. This distinction does not reflect in the
reverse mathematics of the infinitary principle, but it appears to
produce a difference in the effective combinatorics.
For n=2, we provide an exact characterization of the effectivity
of the principle, and for all values of n, we provide an exact
characterization of the reverse mathematical strength of the
This work is joint with Peter Cholak, Ludovic Patey, Mariya Soskova,
and Dan Turetsky.
Jack H. Lutz
Title: Algorithmic dimensions and fractal geometry
Abstract: This talk will review the Σ01 notions of algorithmic information and dimension and survey very recent applications of these to classical (non-algorithmic) questions in fractal geometry. These applications include N. Lutz and D. Stull's strengthened lower bounds on the dimensions of generalized Furstenberg sets and N. Lutz's extension of the fractal intersection formulas in Euclidean space from Borel sets to arbitrary sets.
Title: Structures computable without delay
Abstract: Various effects related to unbounded search are usually overlooked in computable structure theory, yet there is a lot to say.
Using primitive recursion we formally measure and compare unbounded delays in computable algebraic structures.
The audience may find some of the results counterintuitive, and the technical depth of some proofs may seem unexpected.
(The talk is based on 3 papers jointly written with Kalimullin and Ng.)
Title: Baire codes for Borel sets in reverse mathematics
Abstract: Statements involving Borel codes are difficult to handle below the
level of ATR0 in reverse mathematics. One way to simplify
the coding in
certain settings is to replace the Borel sets by Baire codes. In this talk,
I will give some motivation from the Dual Ramsey theorem for using Baire
codes and I will discuss the complexity of finding Baire codes. This work is
joint with Damir Dzhafarov, Stephen Flood and Linda Brown Westrick.
- Sept 23rd 2008 Antonio
Montalbán - Logan Axon - Joe Miller
- Nov 11th 2008 Chris
Conidis - Keng Meng (Selwyn) Ng - Peter Gerdes
- Feb 3rd 2009 David
Diamondstone - Bart Kastermans - Richard A. Shore
- April 21st 2009 Dan Turetsky
- Julia Knight - Ted Slaman
- Sept 29th 2009 Carl Jockusch
- Rachel Epstein - Rebecca Weber
- Jan 26th 2010 Sara Quinn -
John Wallbaum - Steffen Lempp - Reed Solomon
- May 11th 2010 Adam Day -
Liang Yu - Rod Downey - Boris Zilber
- Sept 28th 2010 Maurice
Chiodo - Peter Gerdes - Damir Dzhafarov - Andy Lewis
- Feb 15th 2011 Uri Andrews -
Paola D'Aquino - David Diamondstone - Christopher Porter -
- Nov 1st 2011 Mingzhong Cai -
Chris Conidis - Stephen Flood -
Jeff Hirst - Asher Kach
- Nov 15th 2012 Achilles Beros
- Rod Downey - Jesse Johnson - Sam Sanders - Steven VanDendriessche -
- April 2nd 2013 Howard
Becker - Denis Hirschfeldt - Paul Schupp
- October 1st 2013 Peter Cholak
- Mushfeq Khan - Victor Ocasio-González - Jonathan Stephenson
- April 29th, 2014 Rod Downey -
Noam Greenberg - Gregory Igusa - Alexander Melnikov - Kyle Riggs
- September 30th, 2014 Eric Astor -
Quinn Culver - Jack Lutz - Timothy McNicholl
- February 17th, 2015 Carl Jockusch -
Julia Knight - Steffen Lempp
- January 28th, 2016 Reese Johnston -
Rutger Kuyper - Mariya Soskova - Mars Yamaleev
- October 22nd and 23rd, 2016 Special Meeting in Honor of Carl Jockusch's 75th Birthday
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