Colin Jahel

activity

20192025

most citedExtending partial automorphisms of

n

-partite tournaments

1 citations · 2 across the 11 of their papers we have counts for

collaborators

13 papers

math.GR2025

On dissociated infinite permutation groups

Rémi Barritault, Colin Jahel, Matthieu Joseph

The goal of this paper is threefold. First, we describe the notion of dissociation for closed subgroups of the group of permutations on a countably infinite set and explain its num…

math.PR2024

A non-de Finetti theorem for countable Euclidean spaces

Colin Jahel, Pierre Perruchaud

The classical de Finetti Theorem classifies the $Sym (N)$ -invariant probability measures on $[0, 1]^{N}$ . More precisely it states that those invariant measu…

math.GR2024

Unitary Representations of the Isometry Groups of Urysohn Spaces

Rémi Barritault, Colin Jahel, Matthieu Joseph

We obtain a complete classification of the continuous unitary representations of the isometry group of the rational Urysohn space $QU$ . As a consequence, we show…

math.LO2024

Quasi-invariant measures concentrating on countable structures

Clinton Conley, Colin Jahel, Aristotelis Panagiotopoulos

Countable $L$ -structures $N$ whose isomorphism class supports a permutation invariant probability measure in the logic action have been characterized by Ackerma…

math.LO2024

When invariance implies exchangeability (and applications to invariant Keisler measures)

Samuel Braunfeld, Colin Jahel, Paolo Marimon

We study the problem of when, given a countable homogeneous structure $M$ and a space $S$ of expansions of $M$ , every $Aut (M)$ -invariant probability measure on $S$ is exch…

math.CO2024

Extension property for partial automorphisms of the $n$ -partite and semigeneric tournaments

Jan Hubička, Colin Jahel, Matěj Konečný +1

We present a proof of the extension property for partial automorphisms (EPPA) for classes of finite $n$ -partite tournaments for $n \in {2, 3, \dots, ω}$ , and for the class of finit…

math.DS2023

Stabilizers for ergodic actions and invariant random expansions of non-archimedean Polish groups

Colin Jahel, Matthieu Joseph

Let $G$ be a closed permutation group on a countably infinite set $Ω$ , which acts transitively but not highly transitively. If $G$ is oligomorphic, has no algebraicity and weakly e…

math.CO2022

Asymptotic Theories of Classes Defined by Forbidden Homomorphisms

Manuel Bodirsky, Colin Jahel

We study the first-order almost-sure theories for classes of finite structures that are specified by homomorphically forbidding a set $F$ of finite structures. If $\mathc…

math.DS2020

Invariant measures on products and on the space of linear orders

Colin Jahel, Todor Tsankov

Let $M$ be an $ℵ_{0}$ -categorical structure and assume that $M$ has no algebraicity and has weak elimination of imaginaries. Generalizing classical theorems of de Finetti and Ry…

math.DS2020

Minimal model-universal flows for locally compact Polish groups

Colin Jahel, Andy Zucker

Let $G$ be a locally compact Polish group. A metrizable $G$ -flow $Y$ is called model-universal if by considering the various invariant probability measures on $Y$ , we can recover e…

math.CO2019★ 1 cited

Extending partial automorphisms of $n$ -partite tournaments

Jan Hubička, Colin Jahel, Matěj Konečný +1

We prove that for every $n \geq 2$ the class of all finite $n$ -partite tournaments (orientations of complete $n$ -partite graphs) has the extension property for partial automorphisms…

math.DS2019

Unique ergodicity of the automorphism group of the semigeneric directed graph