Cyril Houdayer

activity

20232026

collaborators

5 papers

math.OA2026

The classification of flows on $II_{1}$ factors and Connes' bicentralizer problem

Cyril Houdayer, Amine Marrakchi

We settle two long-standing open problems in von Neumann algebras. First, we show that every outer flow with full Connes spectrum on the hyperfinite $II_{1}$ factor has the…

math.OA2026

Uniqueness of almost periodic outer flows on the hyperfinite type $II_{1}$ factor

Cyril Houdayer, Amine Marrakchi

We show that any almost periodic outer flow $α : R ↷ R$ on the hyperfinite type $II_{1}$ factor with Connes' spectrum $Γ (α) = R$ satisfies the…

math.OA2025

Weyl groups and rigidity of von Neumann algebras

Cyril Houdayer, Adrian Ioana

Let $G$ be a noncompact semisimple algebraic group with trivial center, $S < G$ a maximal split torus, $H < G$ the centralizer of $S$ in $G$ and $Γ < G$ an irreducible lattice. Cons…

math.DS2024

Strong primeness for equivalence relations arising from Zariski dense subgroups

Daniel Drimbe, Cyril Houdayer

We show that orbit equivalence relations arising from essentially free ergodic probability measure preserving actions of Zariski dense discrete subgroups of simple algebraic groups…

math.OA2023

Asymptotic freeness in tracial ultraproducts

Cyril Houdayer, Adrian Ioana

We prove novel asymptotic freeness results in tracial ultraproduct von Neumann algebras. In particular, we show that whenever $M = M_{1} * M_{2}$ is a tracial free product von Neuma…

The classification of flows on II1​ factors and Connes' bicentralizer problem

Uniqueness of almost periodic outer flows on the hyperfinite type II1​ factor

Weyl groups and rigidity of von Neumann algebras

Strong primeness for equivalence relations arising from Zariski dense subgroups

Asymptotic freeness in tracial ultraproducts

The classification of flows on $II_{1}$ factors and Connes' bicentralizer problem

Uniqueness of almost periodic outer flows on the hyperfinite type $II_{1}$ factor