Ziemowit Kostana: Cohen-like poset for adding Fraisse limits

Tuesday, May 5, 2020 17:15

Location: Zoom.us: if you want to participate please contact organizers

Speaker:
Ziemowit Kostana (University of Warsaw)

Title: Cohen-like poset for adding Fraisse limits

Abstract. There exist a natural forcing notion which turns given countable set into a Fraisse limit of a given Fraisse class. This long-known phenomenon provided a rough intuition that Fraisse limits, as "generic structures", have some connections with forcing. The goal of the talk is to look at some particular instances and possible applications of this idea.

Aleksandra Kwiatkowska: Simplicity of the automorphism groups of homogeneous structures

Tuesday, April 28, 2020 17:15

Location: Zoom.us: if you want to participate please contact organizers

Speaker:
Aleksandra Kwiatkowska

Title: Simplicity of the automorphism groups of homogeneous structures

Abstract. We prove simplicity for the automorphism groups of order and tournament expansions of homogeneous structures like the bounded Urysohn space and the random graph. In particular, we will show that the automorphism group of the linearly ordered random graph is a simple group. The talk will be based on a preprint https://arxiv.org/pdf/1908.05249.pdf joint with Filippo Calderoni and Katrin Tent.

Aleksander Cieślak: Forcing with wider Silver

Tuesday, April 21, 2020 17:15

Location: Zoom.us: if you want to participate please contact organizers

Speaker:
Aleksander Cieślak

Title: Forcing with wider Silver

Abstract. We are going to establish basic properties of diagonal version of Silver forcing. Such forcing consists of partial functions \(p:\omega\rightarrow\omega\) with infinite codomain and \(p(n)<=n\) for each \(n\in dom(p)\). Cardinal characteristics of continuum will be calculated.