MidWest Model Theory Day
Tuesday, April 4, 2017 at UIC
Spring 2017 MWMT is April 4.
Speakers: Erik Walsberg, Vince Guingona, Nadja Hempel
All talks are about an hour long including questions, in SEO 636.
There will also be coffee & cookies in 636.
- 11am: Meet on the first floor of SEO if you're already here. We will leave to lunch at 11:25.
- 11:30am: Lunch at Moxee.
- 1pm: Vince Guingona
- 2:30: Erik Walsberg
- 4pm: Nadja Hempel
- 5:30pm: Dinner at Jaks Tap
It is probably easiest to park in the university parking lot on Morgan
St. between Roosevelt and Taylor; please bring in parking tickets, and
we can validate them.
Let us know (jfreitag at uic dot edu) if you are planning to come to
lunch and/or dinner so we can make approximately correct reservations!
Speaker: Vince Guingona
Title: Fraisse classes and model-theoretic dividing lines
discuss the notion of positive local combinatorial dividing lines in
model theory, showing how these relate to certain Fraisse
classes. I examine this relationship vis-a-vis several well-known
examples, including stability, NIP, and n-dependence. I also
explore the question of when two Fraisse classes give rise to the same
This work is joint with C. D. Hill.
Speaker: Nadja Hempel
Title: Mekler constructions in NIP and n-dependent theories
Given a so called nice graph (no triangles, no squares, for any choice
of two distinct vertices there is a third vertex which is connected to
one and not the other), Mekler considered the 2-nilpotent subgroup
generated by the vertices of the graph in which two elements given by
vertices commute if and only if there is an edge between them. These
groups form an interesting collection of examples from a model
theoretic point of view. It was shown that such a group is stable if
and only if the corresponding graph is stable and Baudisch generalized
this fact to the simple theory context. In a joint work with Chernikov,
we were able to verify this result for NIP and even n-dependent
theories. This leads to the existence of groups which are
(n+1)-dependent but not n-dependent, providing the first algebraic
objects witnessing the strictness of these hierarchy (work in progress).