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We introduce the notion of a rank-3 generalized Clifford manifold, defined by a triple of generalized complex structures satisfying Clifford-type relations. We show that every such structure canonically induces a generalized hypercomplex…

Complex Variables · Mathematics 2026-03-17 Guangzhen Ren , Kai Tang , Qingyan Wu

This paper investigates a question of Radjavi: Which multiplicative semigroups in B(H) have all their ideals selfadjoint (called herein selfadjoint-ideal (SI) semigroups)? We proved this property is a unitary invariant for B(H)-semigroups,…

Functional Analysis · Mathematics 2019-04-03 Sasmita Patnaik , Gary Weiss

When a semigroup has a unary operation, it is possible to define two binary operations, namely, left and right division. In addition it is well known that groups can be defined in terms of those two divisions. The aim of this paper is to…

Group Theory · Mathematics 2012-10-01 Joao Araujo , Michael Kinyon

In this paper subcentral (resp., central) idempotent series and composition subcentral (resp., central) idempotent series in an inverse semigroup are introduced and investigated. It is shown that if $S=EG$ is a factorizable inverse monoids…

Group Theory · Mathematics 2024-12-30 Dong-lin Lei , Jin-xing Zhao , Xian-zhong Zhao

The power semigroup of a semigroup $ S $ is the semigroup of all nonempty subsets of $ S $ equipped with the naturally defined multiplication. A class $\mathcal{K} $ of semigroups is globally determined if any two members of $ \mathcal{K} $…

Group Theory · Mathematics 2025-02-11 Baomin Yu , Xianzhong Zhao

Let $S\subseteq R$ be a multiplicatively closed subset of a ring $R$. We extend several results on integral domains to their $S$-versions and establish the $S$-version of Krull intersection theorem. We also show that if $R$ is an $S$-field,…

Commutative Algebra · Mathematics 2025-12-24 Tushar Singh , Gyanendra K. Verma , Shiv Datt Kumar

Inverses semigroups and orthodox semigroups are either defined in terms of inverses, or in terms of the set of idempotents E(S). In this article, we study analogs of these semigroups defined in terms of inverses modulo Green's relation H,…

Group Theory · Mathematics 2012-03-19 Xavier Mary

We prove a structure result on proper extensions of two-sided restriction semigroups in terms of partial actions, generalizing respective results for monoids and for inverse semigroups and upgrading the latter. We introduce and study…

Rings and Algebras · Mathematics 2024-10-29 Mikhailo Dokuchaev , Mykola Khrypchenko , Ganna Kudryavtseva

We construct an invariant of t-structures on the derived category of a Noetherian ring. This invariant is complete when restricting to the category of quasi-coherent complexes, and also gives a classification of nullity classes with the…

Commutative Algebra · Mathematics 2007-05-23 Don Stanley

Let $R$ be a one-dimensional, local, Noetherian domain, $\R$ the integral closure of $R$ in its quotient field and $v(R)$ the value set defined by the usual valuation. The aim of the paper is to study the non-negative invariant…

Commutative Algebra · Mathematics 2009-06-01 A. Oneto , E. Zatini

Let $T(X)$ (resp. L(V)) be the semigroup of all transformations (resp. linear transformations) of a set $X$ (resp. vector space $V$). For a subset $Y$ of $X$ and a subsemigroup $\mathbb{S}(Y)$ of $T(Y)$, consider the subsemigroup…

Group Theory · Mathematics 2023-03-08 Mosarof Sarkar , Shubh N. Singh

Clifford theory establishes a relation between the representation theory of a finite group and its normal subgroups. In this paper, we establish the Clifford theory for the modular representations of finite groups. The proofs are based on…

Representation Theory · Mathematics 2025-03-05 Devjani Basu

A completely simple semigroup S is a semigroup without zero which has no proper ideals and contains a primitive idempotent. It is known that S is a regular semigroup and any completely simple semigroup is isomorphic to the Rees matrix…

Group Theory · Mathematics 2017-01-24 Azeef Muhammed P A , A R Rajan

In this paper, for given an algebraic theory $T$ whose category $C$ of models is semi-abelian, we consider the topological models of $T$ called topological $T$-algebras and obtain some results related to the fundamental groups of…

Category Theory · Mathematics 2018-01-29 Osman Mucuk , Serap Demir

In this paper, we discuss the structure of doubly commuting semigroups of isometries. We record a new proof of Cooper's theorem in the Hilbert module setting. We discuss the Fell topology on the set of equivalence classes of irreducible,…

Operator Algebras · Mathematics 2025-09-04 C. H. Namitha , S. Sundar , Shankar Veerabathiran

We present a study of semigroup compactifications of a semitopological semigroup $S$ using certain filters on $S$. We characterize closed subsemigroups and closed left, right, and two-sided ideals in any semigroup compactification of any…

General Topology · Mathematics 2013-07-12 Tomi Alaste

Let $D$ be an integrally closed domain with quotient field $K$ and $A$ a torsion-free $D$-algebra that is finitely generated as a $D$-module and such that $A\cap K=D$. We give a complete classification of those $D$ and $A$ for which the…

Rings and Algebras · Mathematics 2026-03-10 Giulio Peruginelli , Nicholas J. Werner

The purpose of this paper is to revisit the proof of the Gearhardt-Pr\"uss-Hwang-Greiner theorem for a semigroup $S(t)$, following the general idea of the proofs that we have seen in the literature and to get an explicit estimate on $\Vert…

Optimization and Control · Mathematics 2021-03-12 Bernard Helffer , Johannes Sjöstrand

Let $\boldsymbol{B}_{[0,\infty)}$ be the semigroup which is defined in the Ahre paper \cite{Ahre=1981}. The semigroup $\boldsymbol{B}_{[0,\infty)}$ with the induced usual topology $\tau_u$ from $\mathbb{R}^2$, with the topology $\tau_L$…

Group Theory · Mathematics 2024-01-15 Oleg Gutik , Markian Khylynskyi

We define classes of quantum states associated to isotropic submanifolds of cotangent bundles. The classes are stable under the action of semiclassical pseudo-differential operators and covariant under the action of semiclassical Fourier…

Analysis of PDEs · Mathematics 2016-06-22 Victor Guillemin , Alejandro Uribe , Zuoqin Wang