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In this paper we define a new product-like binary operation on directed graphs, and we discuss some of its properties. We also briefly discuss its application in constructing the subtyping relation in generic nominally-typed object-oriented…

Programming Languages · Computer Science 2018-07-17 Moez A. AbdelGawad

In this paper we present a new embedding of a semigroup into a semiband (idempotent-generated semigroup) of depth 4 (every element is the product of 4 idempotents) using a semidirect product construction. Our embedding does not assume that…

Group Theory · Mathematics 2019-06-04 Luis Oliveira

We describe a general technique for embedding certain amalgamated products into direct products. This technique provides us with a way of constructing a host of finitely presented subgroups of automatic groups which are not even…

Group Theory · Mathematics 2008-02-03 Gilbert Baumslag , Martin Bridson , Charles Miller , Hamish Short

In this work we present a new definition to the Partial Crossed Product by actions of inverse semigroups in a C^*-algebra, without using the covariant representations as Sieben did in [5]. Also we present an isomorphism between the partial…

Operator Algebras · Mathematics 2008-05-26 Ruy Exel , Felipe Vieira

We introduce a topology on the space of actions modulo weak equivalence finer than the one previously studied in the literature. We show that the product of actions is a continuous operation with respect to this topology, so that the space…

Dynamical Systems · Mathematics 2015-01-26 Peter Burton

In this paper, we construct a partial group \(\mathcal{P}(F)\) that represents the "partial symmetry" inherent in a subset \(F\) of \(d\)-dimensional Euclidean space. In cases where \(F\) is not connected, \(\mathcal{P}(F)\) captures more…

Group Theory · Mathematics 2025-08-27 Takahiro Hayashi

Motivated by computational efficiency in algebraic automata theory here we define the cascade product of permutation groups as an external product, as a generic extension. It is the most general hierarchical product that uses arbitrary…

Group Theory · Mathematics 2021-08-31 Attila Egri-Nagy , Chrystopher L. Nehaniv

In this article, we introduce an extrinsic approach to the notion of semi-direct product, an intrinsic one (namely inside the category Gp of group itself) having been already done elsewhere. This will led us to focus our attention on two…

Category Theory · Mathematics 2026-02-09 Dominique Bourn

The recently developed theory of partial actions of discrete groups on $C^*$-algebras is extended. A related concept of actions of inverse semigroups on $C^*$-algebras is defined, including covariant representations and crossed products.…

funct-an · Mathematics 2008-02-03 Nandor Sieben

We introduce partial semigroupoid actions on sets and demonstrate that each such action admits universal globalization. Our construction extends the universal globalization for partial category actions given by P. Nystedt (Lundstr\"om) and…

Rings and Algebras · Mathematics 2025-12-11 Rafael Haag Petasny , Thaísa Tamusiunas

There exists two types of semi-direct products between a Lie group $G$ and a vector space $V$. The left semi-direct product, $G \ltimes V$, can be constructed when $G$ is equipped with a left action on $V$. Similarly, the right semi-direct…

Mathematical Physics · Physics 2014-10-02 Leonardo J. Colombo , Henry O. Jacobs

We provide a new and much simpler structure for quasi-ideal adequate transversals of abundant semigroups in terms of spined products, which is similar in nature to that given by Saito for weakly multiplicative inverse transversals of…

Group Theory · Mathematics 2010-03-23 Jehan Al-Bar , James Renshaw

We introduce an external version of the internal r-fold semidirect product of groups (SDP) of Carrasco and Cegarra. Just as for the classical external SDP, certain algebraic data are required to guarantee associativity of the construction.…

Algebraic Topology · Mathematics 2015-03-17 Eric R. Antokoletz

The operation of zig-zag products of graphs is the analogue of the semidirect product of groups. Using this observation, we present a categorical description of zig-zag products in order to generalize the construction for the category of…

Combinatorics · Mathematics 2007-05-23 Samuel Cooper , Dominic Dotterrer , Stratos Prassidis

We consider group-subgroup pairs in which the group is a semidirect product and the subgroup is contained in the normal part. We give conditions for the pair to be a Hecke pair and we show that the enveloping Hecke algebra and Hecke…

Operator Algebras · Mathematics 2007-05-23 Marcelo Laca , Nadia S. Larsen

Let $G$ be a group which admits the structure of an iterated semidirect product of finitely generated free groups. We construct a finite, free resolution of the integers over the group ring of $G$. This resolution is used to define…

alg-geom · Mathematics 2007-07-02 Daniel C. Cohen , Alexander I. Suciu

In this work we propose composition products in the class of complex harmonic functions so that the composition of two such functions is again a complex harmonic function. From here we begin the study of the iterations of the functions of…

Complex Variables · Mathematics 2022-02-08 Luis E. Benítez , Raúl Felipe

Let G be a group and let P be a subsemigroup of G. In order to describe the crossed product of a C*-algebra A by an action of P by unital endomorphisms we find that we must extend the action to the whole group G. This extension fits into a…

Operator Algebras · Mathematics 2010-03-16 Ruy Exel

The semiring of discrete dynamical systems is a simple algebraic model for modularity in deterministic systems. The objects of the semiring are finite transformations (viewed as directed graphs and regarded up to isomorphism), the sum of…

Rings and Algebras · Mathematics 2026-03-30 Maximilien Gadouleau , Marianne Johnson

We ascertain conditions and structures on categories and semigroups which admit the construction of pseudo-products and trace products respectively, making their connection as precise as possible. This topic is modelled on the ESN Theorem…

Rings and Algebras · Mathematics 2022-10-14 D. G. FitzGerald , M. K. Kinyon