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In this article, we aim to provide a satisfactory algebraic description of the set of affiliated operators for von Neumann algebras. Let $\mathscr{M}$ be a von Neumann algebra acting on a Hilbert space $\mathcal{H}$, and let…

Operator Algebras · Mathematics 2024-10-03 Indrajit Ghosh , Soumyashant Nayak

We approach a problem of realising algebraic objects in a certain universal equivariant stable homotopy theory; the global homotopy theory of Schwede. Specifically, for a global ring spectrum $R$, we consider which classes of ring…

Algebraic Topology · Mathematics 2021-08-31 Jack Morgan Davies

A ring $R$ satisfies the {\it strong rank condition} (SRC) if, for every natural number $n$, the free $R$-submodules of $R^n$ all have rank $\leq n$. Let $G$ be a group and $R$ a ring strongly graded by $G$ such that the base ring $R_1$ is…

Rings and Algebras · Mathematics 2019-08-16 Peter Kropholler , Karl Lorensen

In a semiprime ring, von Neumann regular elements are determined by their inner inverses. In particular, for elements $a,b$ of a von Neumann regular ring $R$, $a=b$ if and only if $I(a)=I(b)$, where $I(x)$ denotes the set of inner inverses…

Rings and Algebras · Mathematics 2018-07-03 Adel Alahmadi , S. K. Jain , André Leroy

Let $\mathfrak{a}$ be an ideal of a commutative Noetherian ring $R$ and $M$ a finitely generated $R$-module. In this paper we proved that if $\operatorname{Supp}\mathfrak{F}_\mathfrak{a}^i(M)$ is finite for all $i<t$, then so is…

Commutative Algebra · Mathematics 2021-04-06 Behruz Sadeqi

Generalizing von Neumann's result on type II$_1$ von Neumann algebras, we characterize lattice isomorphisms between projection lattices of arbitrary von Neumann algebras by means of ring isomorphisms between the algebras of locally…

Operator Algebras · Mathematics 2020-11-18 Michiya Mori

One says that a ring homomorphism $R \rightarrow S$ is Ohm-Rush if extension commutes with arbitrary intersection of ideals, or equivalently if for any element $f\in S$, there is a unique smallest ideal of $R$ whose extension to $S$…

Commutative Algebra · Mathematics 2021-03-01 Neil Epstein , Jay Shapiro

Let $R$ denote a commutative Noetherian ring, $I$ an ideal of $R$, and let $S$ be a multiplicatively closed subset of $R$. In \cite{Ra1}, Ratliff showed that the sequence of sets ${\rm Ass}_RR/\bar{I}\subseteq {\rm Ass}_RR/\bar{I^2}…

Commutative Algebra · Mathematics 2013-08-30 Saeed Jahandoust , Reza Naghipour

For two ideals $I$ and $J$ of a noetherian ring, we characterize, in terms of the vanishing of Tor modules, when the associated graded ring of the sum $I+J$ is isomorphic to the tensor product of the associated graded ring of $I$ and the…

Commutative Algebra · Mathematics 2007-05-23 Francesc Planas-Vilanova

For a Noetherian regular ring $S$ and for a fixed ideal $J\subset S$, assume that the associated primes of local cohomology module $H^i_J(S)$ does not contain $p$ for some $i\geq 0$, and we call this as a property…

Commutative Algebra · Mathematics 2015-12-18 Rajsekhar Bhattacharyya

We prove a generalization of the Hochster-Roberts-Boutot-Kawamata Theorem conjectured by Aschenbrenner and the author: let $R\to S$ be a pure homomorphism of equicharacteristic zero Noetherian local rings. If $S$ is regular, then $R$ is…

Commutative Algebra · Mathematics 2013-09-27 Hans Schoutens

We completely characterize when the algebra of an ample groupoid with coefficients in an arbitrary unital ring is von Neumann regular and, more generally, when the algebra of a graded ample groupoid is graded von Neumann regular. Our main…

Rings and Algebras · Mathematics 2025-05-13 Benjamin Steinberg , Daniel W. van Wyk

In this note we describe a general elementary procedure to attach a fusion ring to any Kac-Moody algebra of affine type. In the case of untwisted affine algebras, they are usual fusion rings in the literature. In the case of twisted affine…

Representation Theory · Mathematics 2019-07-19 Jiuzu Hong

We consider a circle of ideas involving differential algebra, local Noetherian rings, and their generic formal fibers. Connecting these ideas gives rise to what we term a "twisted" subring $R$ of a ring $S$. Each such subring $R$ arises as…

Commutative Algebra · Mathematics 2012-04-20 Bruce Olberding

Let R be an associative ring with identity, and let T be a tilting right R-module, with S=End(T). It is known that if R is a Noetherian algebra that satisfies the Auslander-Reiten conjecture, then so is S. In this paper, we consider the…

Representation Theory · Mathematics 2025-07-29 Kamran Divaani-Aazar , Ali Mahin Fallah , Massoud Tousi

We study possible noncommutative (operator algebra) variants of the classical Hoffman-Rossi theorem from the theory of function algebras. In particular we give a condition on the range of a contractive weak* continuous homomorphism defined…

Operator Algebras · Mathematics 2019-05-21 David P. Blecher , Luis C. Flores , Beate G. Zimmer

Let $A$ be an algebra over a commutative ring $R$. If $R$ is noetherian and $A^\circ$ is pure in $R^A$, then the categories of rational left $A$-modules and right $A^\circ$-comodules are isomorphic. In the Hopf algebra case, we can also…

Rings and Algebras · Mathematics 2007-05-23 J. Y. Abuhlail , J. Gomez-Torrecillas , F. J. Lobillo

This survey provides a comprehensive overview of the recent advancements in the theory of ``uniformly $S$''-algebraic structures in commutative ring theory. Originating from the classical concepts of Noetherian, coherent, von Neumann…

Commutative Algebra · Mathematics 2026-02-17 Xiaolei Zhang , Wei Qi

We present a sufficient condition for irreducibility of forcing algebras and study the (non)-reducedness phenomenon. Furthermore, we prove a criterion for normality for forcing algebras over a polynomial base ring with coefficients in a…

Commutative Algebra · Mathematics 2017-07-28 Danny A. J. Gomez-Ramirez , Holger Brenner

We consider the general linear group as an invariant of von Neumann factors. We prove that up to complement, a set consisting of all idempotents generating the same right ideal admits a characterisation in terms of properties of the general…

Operator Algebras · Mathematics 2017-12-29 Thierry Giordano , Adam Sierakowski