5 papers
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…
Extension property for partial automorphisms of the -partite and semigeneric tournaments
Jan HubiÄka, Colin Jahel, MatÄj KoneÄný +1
We present a proof of the extension property for partial automorphisms (EPPA) for classes of finite -partite tournaments for , and for the class of fini…
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 and a space of expansions of , every -invariant probability measure on is exch…
A non-de Finetti theorem for countable Euclidean spaces
Colin Jahel, Pierre Perruchaud
The classical de Finetti Theorem classifies the -invariant probability measures on . More precisely it states that those invariant measu…
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 . As a consequence, we show…