Calendar

Dec
15
Tue
Keita Yokoyama (Japan Advanced Institute of Science and Technology)
Dec 15 @ 2:30 pm – 3:30 pm

Title: Automorphism argument and reverse mathematics
by Keita Yokoyama (Japan Advanced Institute of Science and Technology) as part of Computability theory and applications

Abstract
In the study of models of Peano (or first-order) arithmetic, there are
many results on recursively saturated models and their automorphisms.
Here, we apply such an argument to models of second-order arithmetic
and see that any countable recursively saturated model (M,S) of WKL_0*
is isomorphic to its countable coded omega-submodel if
Sigma_1-induction fails in (M,S). From this result, we see some
interesting but weird properties of WKL_0* with the absence of
Sigma_1-induction such as the collapse of analytic hierarchy. This
argument can also be applied to the reverse mathematical study of
Ramsey’s theorem for pairs (RT22), and we see some new relations
between the computability-theoretic characterizations of RT22 and the
famous open question on the first-order part of RT22+RCA_0.
This work is a part of a larger project joint with Marta Fiori
Carones, Leszek Kolodziejczyk, Katarzyna Kowalik and Tin Lok Wong.

Jan
11
Mon
First day of instruction
Jan 11 all-day
Mar
9
Tue
3pm HST Jonas Balisacan presents his Masters project on: ENERGY MINIMIZING STROKES FOR THE 2D ROTATING COPEPOD ZOOPLANKTON All are welcome to join us!
Mar 9 @ 3:00 pm – 4:00 pm
Mar
15
Mon
Spring recess
Mar 15 – Mar 19 all-day
Mar
19
Fri
Yuliia Kravchenko’s thesis presentation on: Central Sets of Simplicial Complexes
Mar 19 @ 2:00 pm – 3:00 pm
Apr
16
Fri
Lisa Ritter’s PhD defense on Superintegrable systems, exceptional polynomial and solutions to Painleve equations
Apr 16 @ 1:00 pm – Apr 16 @ 2:00 pm
Apr
20
Tue
JoeAnna McDonald MA presentation
Apr 20 @ 3:30 pm – 4:30 pm
Apr
27
Tue
Ikenna Nometa: MA presentation
Apr 27 @ 3:00 pm – 4:00 pm