6 papers
Ramsey theory and topological dynamics of 0-dimensional flows
Krzysztof Krupiński, Junguk Lee, Slavko Moconja
We introduce several Ramsey-theoretic properties of 0-dimensional ambits and obtain their dynamical characterizations. In consequence, we obtain Ramsey-theoretic criteria for trivi…
Haar decompression and amenability of Ellis flows
Daniel Max Hoffmann, Krzysztof Krupiński
Let be a tame flow and let be an Ellis group of its enveloping semigroup . Although is a compact Hausdorff topological group in its -topology, the inclus…
On the structure of approximate rings
Krzysztof Krupiński, Simon Machado
By a [-]approximate subring of a ring we mean an additively symmetric subset such that is covered by finitely many [resp.\ ] additive translates…
Convolution semigroups for automorphism dynamics
Kyle Gannon, Daniel Max Hoffmann, Krzysztof Krupiński
Initially motivated by Hrushovski's paper on definability patterns, we obtain homeomorphisms between Ellis semigroups related to natural actions of the automorphism groups of first…
Definable convolution and idempotent Keisler measures III. Generic stability, generic transitivity, and revised Newelski's conjecture
Artem Chernikov, Kyle Gannon, Krzysztof Krupiński
We study idempotent measures and the structure of the convolution semigroups of measures over definable groups. We isolate the property of generic transitivity and demonstrate that…
Generalized locally compact models for approximate groups
Krzysztof Krupiński, Anand Pillay
We give a proof of the existence of generalized definable locally compact models for arbitrary approximate subgroups via an application of topological dynamics in model theory. Our…