A triple of spectra (r, r , r) is said to be admissible if there is a density operator ρ with (Spec ρ, Spec ρ, Spec ρ) = (r, r , r). How can we characterise such triples? It turns out that the admissible spectral triples correspond to Young diagrams (μ, ν, λ) with nonzero Kronecker coefficient gμνλ [4, 13]. This means that the irreducible representation Vλ is contained in the tensor product of ...

In this paper we combine results from [1] and [3] in order to determine the relationship between the deficiency of a group G and the deficiency of a Rees matrix semigroup S over G; in particular, we investigate how the efficiency of S depends on the efficiency of G. We start by defining semigroup and group presentations. Let A be an alphabet. We denote by A the free semigroup on A consisting of...

That is, W0 is the set of all finite products of the generators, allowing repetitions. Let W signify the larger multiplicative semigroup generated by W0 together with {1/2}. We call W the wild semigroup and W0 the Wooley semigroup. The question we consider is: Which integers belong to these semigroups? The sets of integer elements W(Z) := W ∩ Z and W0(Z) := W0 ∩ Z themselves form multiplicative...

We introduce the notion of ideals in implicative semigroups, and then state the characterizations of the ideals. 2000 Mathematics Subject Classification. 20M12, 06F05, 06A06, 06A12.

In this paper we describe the modulus semigroup of the C0-semigroup associated with the linear differential equation with delay { u1ptq Auptq Lut (t ¥ 0), up0q x∈X, u0 f ∈Lpp h, 0;Xq, in the Banach lattice X Lpp h, 0;Xq, where X is a Banach lattice with order continuous norm. The progress with respect to previous papers is that A may be an unbounded generator of a C0-semigroup possessing a modu...

Rauzy graphs of subshifts are endowed with an automaton structure. For Sturmian subshifts, it is shown that its transition semigroup is the syntactic semigroup of the language recognized by the automaton. A projective limit of the partial semigroups of nonzero regular elements of their transition semigroups is described. If the subshift is minimal, then this projective limit is isomorphic, as a...

‎We present a characterization of Arens regular semigroup algebras‎ ‎$ell^1(S)$‎, ‎for a large class of semigroups‎. ‎Mainly‎, ‎we show that‎ ‎if the set of idempotents of an inverse semigroup $S$ is finite‎, ‎then $ell^1(S)$ is Arens regular if and only if $S$ is finite‎.

Generally, in any human field, a Smarandache Structure on a set A means a weak structure W on A such that there exists a proper subset B of A which is embedded with a strong structure S. In [9], Kandasamy studied the concept of Smarandache groupoids, subgroupoids, ideal of groupoids, seminormal subgroupoids, Smarandache Bol groupoids, and strong Bol groupoids and obtained many interesting resul...

Semiheaps are ternary generalisations of involuted semigroups. The first kind of semiheaps studied were heaps, which correspond closely to groups. We apply the radical theory of varieties of idempotent algebras to varieties of idempotent semiheaps. The class of heaps is shown to be a radical class, as are two larger classes having no involuted semigroup counterparts. Radical decompositions of v...

We consider the action of a semigroup S on a standard space E. An orbit coupling of two probability measures on E is a coupling of these measures giving the largest possible weight to the event that the orbits of the two coordinates meet each other. We establish the existence of such orbit couplings for a large class of semigroups S. We also discuss some applications.