Monday, December 12, 2016 

09:15  Opening & Registration 
09:30  10:30  B. Miller Introductory lecture 
10:30  11:00  Coffee break 
11:00  12:00  C. Conley Følner tilings via matchings 
12:00  14:00  Lunch break 
14:00  15:00 
S. Jackson The subshift of finite type and graph homomorphism questions Given a countable group $G$ acting continuously and freely on $F(2^G)$, and given a subshift $S$ of finite type, does there exist a continuous equivariant map from $F(2^G)$ to $S$? We show that the set of subshifts, for the case $G=\mathbb{Z}^n$, for which the answer is yes is semirecursive, but not recursive. Thus, the subshift question is undecidable. We also consider the corresponding question for graph homomorphisms. 
15:00  15:30  Break 
15:30  16:00 
V. Kanovey Definable countable sets of reals with and without definable elements Does any nonempty OD set, especially a set of reals, necessarily have an OD element? The answer is in the positive in some wellknown models, and in the negative in some other generic models. 
Tuesday, December 13, 2016 

09:30  10:30  D. Kerr Actions of amenable groups on the Cantor set and their crossed products 
10:30  11:00  Coffee break 
11:00  12:00  A. Kwiatkowska Cyclically dense conjugacy classes and topological similarity for groups of measurable functions 
12:00  14:00  Lunch break 
14:00  15:00 
F. Le Maître $L^1$ full groups In this talk I will present $L^1$ full groups, which are the measurable analogue of topological full groups. They are cli Polish groups which provide a complete flipconjugacy invariant for measurepreserving invertible ergodic transformations. After establishing some of their basic properties, I will explain why the $L^1$ full group of a measurepreserving ergodic invertible transformation is topologically finitely generated if and only if the transformation has finite entropy. 
15:00  15:30  Break 
15:30  16:30 
D. Lecomte Applications of the representation theorem for Borel sets We recall and apply the DebsSaint Raymond representation theorem for Borel sets to obtain progress concerning problems motivated by the studies of definable countable colourings and Borel equivalence relations. 
Wednesday, December 14, 2016 

10:00  10:30  P. Schlicht Applications of long games in generalized descriptive set theory 
10:30  11:00  Coffee break 
11:00  11:30 
M. Malicki There is no universal Polish metric group with a biinvariant metric. A short proof In a recently published paper, Michal Doucha proved that there is no universal Polish metric group with a biinvariant metric, that is, there does not exist a complete, separable metric group G with a biinvariant metric such that every Polish metric group with a biinvariant metric can be isometrically embedded in G. The same holds for locally compact Polish metric groups with a biinvariant metric. We would like to present a short proof of this result. 
Thursday, December 15, 2016 

09:30  10:30  A. Marks Descriptive set theory and geometrical paradoxes 
10:30  11:00  Coffee break 
11:00  12:00 
R. TuckerDrob Bounded generation and cost We show that any group which is boundedly generated by finitely generated subgroups of infinite index must have cost 1. This leads to a strong positive answer to problem 33.2 in KechrisMiller. This is joint work with Mark Shusterman. 
12:00  14:00  Lunch break 
14:00  15:00 
M. Zelený On Borel chromatic numbers 
15:00  15:30  Break 
15:30  16:30 
J. Zapletal The Florida diagram and its repercussions We show how comparison of various generic extensions of a ground model can yield results in Borel reducibility, independence results in choiceless set theory, and restatements of coding principles on $\omega_1$. 
Friday, December 16, 2016 

09:30  10:30  T. Tsankov Metric Scott analysis Backandforth equivalence relations have been an important tool in model theory and descriptive set theory since their advent in the fifties. They provide Borel approximations to the isomorphism relation that are useful in a variety of settings and are particularly important in infinitary model theory. In this work, we extend the theory to metric structures and describe the connections with infinitary continuous logic. Many classical results have a continuous counterpart (for example, the existence of Scott rank, the LopezEscobar theorem, etc.) but also new features appear that have no analogue in the classical setting and allow the study of equivalence relations other than isomorphism. This is joint work with I. Ben Yaacov, M. Doucha, and A. Nies. 
10:30  11:00  Coffee break 
11:00  12:00  A. Tserunyan Edge slides and ergodic actions We use edgeslidings and saturated disjoint Borel families to give a conceptually simple proof of Hjorth's theorem on cost attained. The same technique yields a strengthening of Hjorth's theorem: the action of the free group can be arranged so that each of the standard generators acts ergodically. The existence of an ergodic action for the first generator immediately follows from a powerful theorem of TuckerDrob, whose proof uses a recent substantial result in probability theory as a black box. Using asymptotic means on graphs and a new notion of packed disjoint Borel families, we give a constructive proof of a weaker version of TuckerDrob's theorem, which is enough to yield most of its known corollaries, including what was needed for our strengthening of Hjorth's theorem. This is joint work with B. Miller. 
12:00  14:00  Lunch break 
14:00  15:00 
A. Törnquist Definability and disjointness modulo various ideals on $\omega$ 