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With each semigroup one can associate a partial algebra, called the biordered set, which captures important algebraic and geometric features of the structure of idempotents of that semigroup. For a biordered set $\mathcal{E}$, one can…

Group Theory · Mathematics 2022-10-07 Igor Dolinka

We extend Grood's tableau construction of irreducible representations of the rook monoid and Steinberg's analogous result for the full transformation monoid. Our approach is characteristic-free and applies to any submonoid $\mathcal{M}(n)$…

Representation Theory · Mathematics 2025-12-30 Mihalis Maliakas , Dimitra-Dionysia Stergiopoulou

The algebraic variety defined by the idempotents of an incidence monoid is investigated. Its irreducible components are determined. The intersection with an antichain submonoid is shown to be the union of these irreducible components. The…

Combinatorics · Mathematics 2022-08-03 Mahir Bilen Can , Ana Casimiro , Antonio Malheiro

In this paper we study the structure of the monoid $\mathbf{I}\mathbb{N}_{\infty}^n$ of cofinite partial isometries of the $n$-th power of the set of positive integers $\mathbb{N}$ with the usual metric for a positive integer $n\geqslant…

Group Theory · Mathematics 2019-09-20 Oleg Gutik , Anatolii Savchuk

A complete system of pairwise orthogonal minimal idempotents for Birman-Murakami-Wenzl algebras is obtained by a consecutive evaluation of a rational function in several variables on sequences of quantum contents of up-down tableaux. A…

Representation Theory · Mathematics 2011-11-11 A. P. Isaev , A. I. Molev , O. V. Ogievetsky

Denote by $\mathcal T_n$ and $\mathcal S_n$ the full transformation semigroup and the symmetric group on the set $\{1,\ldots,n\}$, and $\mathcal E_n=\{1\}\cup(\mathcal T_n\setminus \mathcal S_n)$. Let $\mathcal T(X,\mathcal P)$ denote the…

Group Theory · Mathematics 2017-12-14 Igor Dolinka , James East

The structure of the algebra K[M] of the Chinese monoid M over a field K is studied. The minimal prime ideals are described. They are determined by certain homogeneous congruences on M and they are in a one to one correspondence with…

Rings and Algebras · Mathematics 2011-07-11 Joanna Jaszunska , Jan Okninski

We propose a notion of a proper Ehresmann semigroup based on a three-coordinate description of its generating elements governed by certain labelled directed graphs with additional structure. The generating elements are determined by their…

Rings and Algebras · Mathematics 2024-10-29 Ganna Kudryavtseva , Valdis Laan

We study conjugacy relations on semigroups and monoids, focusing on the relation $a \cfn b$, defined by the existence of $g,h \in S^1$ such that $ag = gb$, $bh = ha$, $hag = b$, and $gbh = a$. This notion emerged as one that yields…

A group is Markov if it admits a prefix-closed regular language of unique representatives with respect to some generating set, and strongly Markov if it admits such a language of unique minimal-length representatives over every generating…

Group Theory · Mathematics 2015-10-21 Alan J. Cain , Victor Maltcev

We construct certain monoids, called tied monoids. These monoids result to be semidirect products finitely presented and commonly built from braid groups and their relatives acting on monoids of set partitions. The nature of our monoids…

Representation Theory · Mathematics 2023-01-05 Diego Arcis , Jesús Juyumaya

The goal of this paper is to use topological methods to compute $\mathrm{Ext}$ between irreducible representations of von Neumann regular monoids in which Green's $\mathscr L$- and $\mathscr J$-relations coincide (e.g., left regular bands).…

Representation Theory · Mathematics 2024-04-05 Benjamin Steinberg

We initiate the study of the expansion $\mathcal{S}(M)$ of a monoid $M$ obtained via the semidirect product of $M$ acting naturally on the left of its power set (regarded as a semilattice under union). We term this the `subset expansion' of…

Rings and Algebras · Mathematics 2025-12-22 Victoria Gould , Marianne Johnson

In our earlier article~\cite{CanSakran} we initiated a study of the complement-finite submonoids of the group of integer points of a unipotent linear algebraic group. In the present article, we continue to develop tools and techniques for…

Algebraic Geometry · Mathematics 2024-07-10 Mahir Bilen Can , Naufil Sakran

We describe a formalism, using groupoids, for the study of rewriting for presentations of inverse monoids, that is based on the Squier complex construction for monoid presentations. We introduce the class of pseudoregular groupoids, an…

Group Theory · Mathematics 2019-05-01 N. D. Gilbert , E. A. McDougall

We describe the local structure of an irreducible algebraic monoid $M$ at an idempotent element $e$. When $e$ is minimal, we show that $M$ is an induced variety over the kernel $MeM$ (a homogeneous space) with fibre the two-sided stabilizer…

Algebraic Geometry · Mathematics 2008-12-14 Michel Brion

We prove that a monomial ideal $I$ generated in a single degree, is polymatroidal if and only if it has linear quotients with respect to the lexicographical ordering of the minimal generators induced by every ordering of variables. We also…

Commutative Algebra · Mathematics 2018-08-21 Somayeh Bandari , Rahim Rahmati-Asghar

In this paper we compute the rank and exhibit a presentation for the monoids of all $P$-stable and $P$-order preserving partial permutations on a finite set $\Omega$, with $P$ an ordered uniform partition of $\Omega$. These (inverse)…

Rings and Algebras · Mathematics 2019-05-29 Rita Caneco , Vítor H. Fernandes , Teresa M. Quinteiro

It is known that the construction of the frame of ideals from a distributive lattice induces a monad whose algebras are precisely the frames and frame homomorphisms. Using the Fakir construction of an idempotent approximation of a monad, we…

Category Theory · Mathematics 2024-05-01 Ando Razafindrakoto

We describe affine monoids whose group of invertible elements is an active semidirect product of a unipotent group and a torus, in terms of comultiplications on the algebra of regular functions. We introduce the notion of a root monoid,…

Algebraic Geometry · Mathematics 2025-10-21 Ekaterina Nistiuk , Yulia Zaitseva