21 citations · 97 across the 18 of their papers we have counts for
20 papers
The No-Core Principle for Stationary Actions and Ends of Stationary Random Subgroups
Yair Hartman, Nadav Kalma
We prove a No-Core Principle for stationary actions of countable groups. Namely, if a Borel set intersects almost every orbit in finitely many points and has positive measure, then…
Stabilizer Subgroups and the Simplicity of Reduced Crossed Products
Yair Hartman, Mehrdad Kalantar
Given a minimal action of a countable group on a compact space , we prove that if the reduced crossed product is simple, then there ex…
On the inclusion of bounded harmonic functions of random walks
Yair Hartman, Aranka Hrušková, Omer Segev
We investigate the conditions under which the space of bounded harmonic functions of a probability measure on a group is contained in that of another measure . We establ…
Retraction Theorems for Group Compactifications
Yair Hartman, Aranka Hrušková, Mehrdad Kalantar +1
We characterize group compactifications of discrete groups for which there exists an equivariant retraction onto the boundary. In particular, we prove an equivariant analogue of Br…
On the amenable subalgebras of group von Neumann algebras
Tattwamasi Amrutam, Yair Hartman, Hanna Oppelmayer
We approach the study of sub-von Neumann algebras of the group von Neumann algebra for countable groups from a dynamical perspective. It is shown that admits a maxi…
Subalgebras, subgroups, and singularity
Tattwamasi Amrutam, Yair Hartman
This paper concerns the non-commutative analog of the Normal Subgroup Theorem for certain groups. Inspired by Kalantar-Panagopoulos, we show that all -invariant subalgebras of $…
Tight inclusions of C*-dynamical systems
Yair Hartman, Mehrdad Kalantar
We study a notion of tight inclusions of C*- and W*-dynamical systems which is meant to capture a tension between topological and measurable rigidity of boundary actions. An import…
Random walks on dense subgroups of locally compact groups
Michael Björklund, Yair Hartman, Hanna Oppelmayer
Let be a countable discrete group, a lcsc totally disconnected group and a homomorphism with dense image. We develop a general and explicit technique wh…
Kudo-Continuity Of Entropy Functionals
Michael Björklund, Yair Hartman, Hanna Oppelmayer
We study in this paper real-valued functions on the space of all sub--algebras of a probability measure space, and introduce the notion of Kudo-continuity, which is an a priori…
The stabilized automorphism group of a subshift
Yair Hartman, Bryna Kra, Scott Schmieding
For a mixing shift of finite type, the associated automorphism group has a rich algebraic structure, and yet we have few criteria to distinguish when two such groups are isomorphic…
Choquet-Deny groups and the infinite conjugacy class property
Joshua Frisch, Yair Hartman, Omer Tamuz +1
A countable discrete group is called Choquet-Deny if for every non-degenerate probability measure on it holds that all bounded -harmonic functions are constant. We s…
Stationary C*-dynamical systems
Yair Hartman, Mehrdad Kalantar
We introduce the notion of stationary actions in the context of C*-algebras. We develop the basics of the theory, and provide applications to several ergodic theoretical and operat…
Furstenberg Entropy of Intersectional Invariant Random Subgroups
Yair Hartman, Ariel Yadin
We study the Furstenberg-entropy realization problem for stationary actions. It is shown that for finitely supported probability measures on free groups, any a-priori possible entr…
Thompson's group F is not strongly amenable
Yair Hartman, Kate Juschenko, Omer Tamuz +1
We show that Thompson's group has a topological action on a compact metric space that is proximal and has no fixed points.
Property (T) and the Furstenberg Entropy of Nonsingular Actions
Lewis Bowen, Yair Hartman, Omer Tamuz
We establish a new characterization of property (T) in terms of the Furstenberg entropy of nonsingular actions. Given any generating measure on a countable group , A. Nevo s…
Generic Stationary Measures and Actions
Lewis Bowen, Yair Hartman, Omer Tamuz
Let be a countably infinite group, and let be a generating probability measure on . We study the space of -stationary Borel probability measures on a topological …
Stabilizer Rigidity in Irreducible Group Actions
Yair Hartman, Omer Tamuz
We consider irreducible actions of locally compact product groups, and of higher rank semi-simple Lie groups. Using the intermediate factor theorems of Bader-Shalom and Nevo-Zimmer…
Furstenberg entropy realizations for virtually free groups and lamplighter groups
Yair Hartman, Omer Tamuz
Let be a discrete group with a generating probability measure. Nevo shows that if has property (T) then there exists an such that the Furstenberg entropy of any $…
An Abramov formula for stationary spaces of discrete groups
Yair Hartman, Yuri Lima, Omer Tamuz
Let (G,mu) be a discrete group equipped with a generating probability measure, and let Gamma be a finite index subgroup of G. A mu-random walk on G, starting from the identity, ret…
Large Semigroups of Cellular Automata
Yair Hartman
In this article we consider semigroups of transformations of cellular automata which act on a fixed shift space. In particular, we are interested in two properties of these semigro…