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We investigate certain classes of normal completely positive (CP) maps on the hyperfinite $II_1$ factor $\mathcal A$. Using the representation theory of a suitable irrational rotation algebra, we propose some computable invariants for such…

Operator Algebras · Mathematics 2007-05-23 Debashish Goswami , Lingaraj Sahu

We prove that there exist uncountably many separable II$_1$ factors whose ultrapowers (with respect to arbitrary ultrafilters) are non-isomorphic. In fact, we prove that the families of non-isomorphic II$_1$ factors originally introduced by…

Operator Algebras · Mathematics 2017-10-18 Rémi Boutonnet , Ionut Chifan , Adrian Ioana

For each countable residually finite group $G$, we present examples of irregular Toeplitz subshifts in $\{0,1\}^G$ that are topo-isomorphic extensions of its maximal equicontinuous factor. To achieve this, we first establish sufficient…

Dynamical Systems · Mathematics 2023-09-06 Jaime Gómez

In 2019, investigation of the so-called factor-invariant cubic graphs was initiated by Alspach, Khodadadpour and Kreher. For a cubic graph $\Gamma$ and a vertex-transitive subgroup $G$ of $\mathrm{Aut}(\Gamma)$, a $2$-factor $\mathcal{C}$…

Combinatorics · Mathematics 2026-01-19 Primož Šparl

We study the triangular array defined by the Graham--Knuth--Patashnik recurrence $T(n,k) = (\alpha n + \beta k + \gamma)\, T(n-1,k)+(\alpha' n + \beta' k + \gamma') \, T(n-1,k-1)$ with initial condition $T(0,k) = \delta_{k0}$ and parameters…

Combinatorics · Mathematics 2021-05-11 Jesús Salas , Alan D. Sokal

We construct irreducible hyperfinite subfactors of index 6 with a prescribed fundamental group from a large family containing all countable and many uncountable subgroups of R_+. We also prove that there are unclassifiably many irreducible…

Operator Algebras · Mathematics 2016-07-25 Arnaud Brothier , Stefaan Vaes

In this paper, we give examples of maximal amenable subalgebras of the free group factor of two generators. More precisely, we consider two copies of the hyperfinite factor $R_i$ of type $\mathrm{II}_1$. From each $R_i$, we take a Haar…

Operator Algebras · Mathematics 2016-10-03 Koichi Shimada

We prove that for any constant $K>0$ there exists a separable group equipped with a complete bi-invariant metric bounded by $K$, isometric to the Urysohn sphere of diameter $K$, that is of `almost-universal disposition'. It is thus an…

Group Theory · Mathematics 2018-02-09 Michal Doucha

We investigate the mapping of Dirac gaugino masses through regions of strong coupling, focussing on SQCD with an adjoint. These models have a well-known Kutasov duality, under which a weakly coupled electric UV description can flow to a…

High Energy Physics - Theory · Physics 2013-12-05 Steven Abel , Daniel Busbridge

We study a class of one-dimensional full branch maps admitting two indifferent fixed points as well as critical points and/or unbounded derivative. Under some mild assumptions we prove the existence of a unique invariant mixing absolutely…

Dynamical Systems · Mathematics 2024-05-28 Douglas Coates , Stefano Luzzatto , Muhammad Mubarak

We introduce the notion of a generalized Jung factor: a II$_1$ factor $M$ for which any two embeddings of $M$ into its ultrapower $M^{\mathcal U}$ are equivalent by an automorphism of $M^{\mathcal U}$. We show that $\mathcal R$ is not the…

Operator Algebras · Mathematics 2020-05-13 Scott Atkinson , Isaac Goldbring , Srivatsav Kunnawalkam Elayavalli

We study the structure of invariant measures for continuous automorphisms of compact metrizable abelian groups satisfying the descending chain condition. We show that the finitely supported invariant measures are weak-* dense in the space…

Dynamical Systems · Mathematics 2025-07-21 Rotem Yaari

Let $G$ be a non-amenable countable group. We show that every almost automorphic $G$-action on a compact Hausdorff space, with a maximal equicontinuous factor whose phase space is a Cantor set, admits invariant probability measures (this…

Dynamical Systems · Mathematics 2023-12-27 María Isabel Cortez , Jaime Gómez

For a large class of nonuniformly expanding maps of $\Bbb R^m$, with indifferent fixed points and unbounded distorsion and non necessarily Markovian, we construct an absolutely continuous invariant measure. We extend to our case techniques…

Dynamical Systems · Mathematics 2007-05-23 Huyi Hu , Sandro Vaienti

In this paper, we introduce a new family of mass-type invariants for time-symmetric initial data in space-times satisfying the Dominant Energy Condition. For positive cosmological constant, these invariants, unlike the total Hawking mass,…

Differential Geometry · Mathematics 2026-04-28 Virginia Agostiniani , Stefano Borghini , Lorenzo Mazzieri

Let $A$ be a commutative $k$-algebra over a field of $k$ and $\Xi$ a linear operator defined on $A$. We define a family of $A$-valued invariants $\Psi$ for finite rooted forests by a recurrent algorithm using the operator $\Xi$ and show…

Combinatorics · Mathematics 2009-02-02 Wenhua Zhao

We introduce a family of maps generating continued fractions where the digit $1$ in the numerator is replaced cyclically by some given non-negative integers $(N_1,\ldots,N_m)$. We prove the convergence of the given algorithm, and study the…

Dynamical Systems · Mathematics 2021-12-09 Karma Dajani , Niels Langeveld

If $\bar\rho$ is an automorphic modulo $p$ Galois representation, it is natural to wonder if automorphic points are Zariski dense in the deformation space of $\bar\rho$. We prove new results in this direction in the case of a unitary group…

Number Theory · Mathematics 2023-05-08 Valentin Hernandez , Benjamin Schraen

In this paper we show how to apply various techniques and theorems (including Pincherle's theorem, an extension of Euler's formula equating infinite series and continued fractions, an extension of the corresponding transformation that…

Number Theory · Mathematics 2019-01-07 James Mc Laughlin , Nancy J. Wyshinski

The mean field like gauge invariant variational method formulated recently, is applied to a topologically massive QED in 3 dimensions. We find that the theory has a phase transition in the Chern Simons coefficient $n$. The phase transition…

High Energy Physics - Theory · Physics 2009-10-28 Ian I. Kogan , Alex Kovner