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1.
A semigroup is regular if it contains at least one idempotent in each ?-class and in each ?-class. A regular semigroup is inverse if it satisfies either of the following equivalent conditions: (i) there is a unique idempotent in each ?-class and in each ?-class, or (ii) the idempotents commute. Analogously, a semigroup is abundant if it contains at least one idempotent in each ?*-class and in each ?*-class. An abundant semigroup is adequate if its idempotents commute. In adequate semigroups, there is a unique idempotent in each ?* and ?*-class. M. Kambites raised the question of the converse: in a finite abundant semigroup such that there is a unique idempotent in each ?* and ?*-class, must the idempotents commute? In this note, we provide a negative answer to this question. 相似文献
2.
Oana Lupaşcu 《数学学报(英文版)》2014,30(2):187-196
We show that the subordination induced by a convolution semigroup(subordination in the sense of Bochner)of a C0-semigroup of sub-Markovian operators on an Lpspace is actually associated to the subordination of a right(Markov)process.As a consequence,we solve the martingale problem associate with the Lp-infinitesimal generator of the subordinate semigroup.We also prove quasi continuity properties for the elements of the domain of the Lp-generator of the subordinate semigroup.It turns out that an enlargement of the base space is necessary.A main step in the proof is the preservation under such a subordination of the property of a Markov process to be a Borel right process.We use several analytic and probabilistic potential theoretical tools. 相似文献
3.
Stanislav Shkarin 《Journal of Mathematical Analysis and Applications》2011,382(2):516-522
We show that for every supercyclic strongly continuous operator semigroup {Tt}t?0 acting on a complex F-space, every Tt with t>0 is supercyclic. Moreover, the set of supercyclic vectors of each Tt with t>0 is exactly the set of supercyclic vectors of the entire semigroup. 相似文献
4.
Daniel Neuenschwander 《Journal of Theoretical Probability》2008,21(4):791-801
Let {μ
t
(i)}
t≥0 (i=1,2) be continuous convolution semigroups (c.c.s.) on a simply connected nilpotent Lie group G. Suppose that μ
1(1)=μ
1(2). Assume furthermore that one of the following two conditions holds:
Then μ
t
(1)=μ
t
(2) for all t≥0. As a complement, we show how our approach can be directly used to give an independent proof of Pap’s result on the uniqueness
of the embedding Gaussian semigroup on simply connected nilpotent Lie groups. In this sense, our proof for the uniqueness
of the embedding semigroup among all c.c.s. of a Gaussian measure can be formulated self-contained.
Dedicated to Professor Wilfried Hazod on the occasion of his 65th birthday. 相似文献
(i) | The c.c.s. {μ t (1)} t≥0 is a Gaussian semigroup (in the sense that its generating distribution just consists of a primitive distribution and a second-order differential operator) |
(ii) | The c.c.s. {μ t (i)} t≥0 (i=1,2) are both Poisson semigroups, and the jump measure of {μ t (1)} t≥0 is determinate (i.e., it possesses all absolute moments, and there is no other nonnegative bounded measure with the same moments). |
5.
Attila Nagy 《Semigroup Forum》2009,78(1):68-76
A semigroup S is said to be ℛ-commutative if, for all elements a,b∈S, there is an element x∈S
1 such that ab=bax. A semigroup S is called a generalized conditionally commutative (briefly,
-commutative) semigroup if it satisfies the identity aba
2=a
2
ba. An ℛ-commutative and
-commutative semigroup is called an
-commutative semigroup. A semigroup S is said to be a right H-semigroup if every right congruence of S is a congruence of S. In this paper we characterize the subdirectly irreducible semigroups in the class of
-commutative right H-semigroups.
Research supported by the Hungarian NFSR grant No T029525. 相似文献
6.
Ciprian G. Gal 《Journal of Mathematical Analysis and Applications》2007,333(2):971-983
In this paper we consider the nonlinear differential equation with deviated argument u′(t)=Au(t)+f(t,u(t),u[φ(u(t),t)]), t∈R+, in a Banach space (X,‖⋅‖), where A is the infinitesimal generator of an analytic semigroup. Under suitable conditions on the functions f and φ, we prove a global existence and uniqueness result for the above equation. 相似文献
7.
ABSTRACT A formula for the rank of an arbitrary finite completely 0-simple semigroup, represented as a Rees matrix semigroup ?0[G; I, Λ; P], is given. The result generalizes that of Ru?kuc concerning the rank of connected finite completely 0-simple semigroups. The rank is expressed in terms of |I|, |Λ|, the number of connected components k of P, and a number r min, which we define. We go on to show that the number r min is expressible in terms of a family of subgroups of G, the members of which are in one-to-one correspondence with, and determined by the nonzero entries of, the components of P. A number of applications are given, including a generalization of a result of Gomes and Howie concerning the rank of an arbitrary Brandt semigroup B(G,{1,…,n}). 相似文献
8.
《代数通讯》2013,41(7):2803-2826
Abstract A transformation semigroup over a set X with N elements is said to be a near permutation semigroup if it is generated by a group of permutations on N elements and by a set of transformations of rank N ? 1. The aim of this paper is to determine computationally efficient conditions to test whether or not a near permutation semigroup is regular. 相似文献
9.
As a generalization of an orthodox semigroup in the class of regular semigroups, a type W semigroup was first investigated
by El-Qallali and Fountain. As an analogy of the type W semigroups in the class of abundant semigroups, we introduce the U-orthodox semigroups. It is shown that the maximum congruence μ contained in
on U-orthodox semigroups can be determined. As a consequence, we show that a U-orthodox semigroup S can be expressed by the spined product of a Hall semigroup W
U
and a V-ample semigroup (T,V). This theorem not only generalizes a known result of Hall-Yamada for orthodox semigroups but also generalizes another known
result of El-Qallali and Fountain for type W semigroups.
This work was supported by National Natural Science Foundation of China (Grant No. 10671151) and Natural Science Foundation
of Shaanxi Province (Grant No. SJ08A06), and partially by UGC (HK) (Grant No. 2160123) 相似文献
10.
Mohammed Ali Faya Ibrahim 《Czechoslovak Mathematical Journal》2004,54(2):303-313
It was shown in [7] that any right reversible, cancellative ordered semigroup can be embedded into an ordered group and as a consequence, it was shown that a commutative ordered semigroup can be embedded into an ordered group if and only if it is cancellative. In this paper we introduce the concept of L-maher and R-maher semigroups and use a technique similar to that used in [7] to show that any left reversible cancellative ordered L or R-maher semigroup can be embedded into an ordered group. 相似文献
11.
R. Exel 《Semigroup Forum》2009,79(1):159-182
By a Boolean inverse semigroup we mean an inverse semigroup whose semilattice of idempotents is a Boolean algebra. We study representations of a given inverse
semigroup
in a Boolean inverse semigroup which are tight in a certain well defined technical sense. These representations are supposed to preserve as much as possible any trace of
Booleanness present in the semilattice of idempotents of
. After observing that the Vagner–Preston representation is not tight, we exhibit a canonical tight representation for any
inverse semigroup with zero, called the regular tight representation. We then tackle the question as to whether this representation is faithful, but it turns out that the answer is often negative.
The lack of faithfulness is however completely understood as long as we restrict to continuous inverse semigroups, a class generalizing the E
*-unitaries.
Partially supported by CNPq. 相似文献
12.
Let G be a refinement of a star graph with center c. Let be the subgraph of G induced on the vertex set V(G)?{c or end vertices adjacent to c}. In this paper, we completely determine the structure of commutative zero-divisor semigroups S whose zero-divisor graph G=Γ(S) and S satisfy one of the following properties: (1) has at least two connected components, (2) is a cycle graph Cn of length n≥5, (3) is a path graph Pn with n≥6, (4) S is nilpotent and Γ(S) is a finite or an infinite star graph. For any finite or infinite cardinal number n≥2, we prove that for any nilpotent semigroup S with zero element 0, S4=0 if Γ(S) is a star graph K1,n. We prove that there is exactly one nilpotent semigroup S such that S3≠0 and Γ(S)≅K1,n. For several classes of finite graphs G which are refinements of a star graph, we also obtain formulas to count the number of non-isomorphic corresponding semigroups. 相似文献
13.
A semigroup is called type-E if the band of its idempotents can be expressed as a direct product of a rectangular band and an ω-chain. For brevity, we call an IC *-bisimple quasi-adequate semigroup of type-E a q
*-bisimple IC semigroup of type-E. In this paper, we characterize q
*-bisimple semigroups by using some kind of generalized Bruck-Reilly extensions. As a consequence, some results concerning
*-bisimple type-A
ω-semigroups given by Asibong-Ibe (Semigroup Forum 31:99–117, 1985) are generalized. 相似文献
14.
Attila Nagy 《Semigroup Forum》2008,76(2):297-308
We say that a semigroup S is a permutable semigroup if the congruences of S commute with each other, that is, α○β=β○α is satisfied for all congruences α and β of S. A semigroup is called a medial semigroup if it satisfies the identity axyb=ayxb. The medial permutable semigroups were examined in Proc. Coll. Math. Soc. János Bolyai, vol. 39, pp. 21–39 (1981), where the medial semigroups of the first, the second and the third kind were characterized, respectively. In Atta Accad.
Sci. Torino, I-Cl. Sci. Fis. Mat. Nat. 117, 355–368 (1983) a construction was given for medial permutable semigroups of the second [the third] kind. In the present paper we give a
construction for medial permutable semigroups of the first kind. We prove that they can be obtained from non-archimedean commutative
permutable semigroups (which were characterized in Semigroup Forum 10, 55–66, 1975).
Research supported by the Hungarian NFSR grant No T042481 and No T043034. 相似文献
15.
Mustapha Mokhtar-Kharroubi 《Journal of Functional Analysis》2009,256(6):1998-2025
This paper deals with two related subjects. In the first part, we give generation theorems, relying on (weak) compactness arguments, for perturbed positive semigroups in general ordered Banach spaces with additive norm on the positive cone. The second part provides new functional analytic developments on semigroup theory for Schrödinger operators in Lp spaces with (L1) Δ-bounded potentials without restriction on the (L1) Δ-bound. In particular, our formalism enlarges a priori the classical Kato class and its subsequent refinements. The connection with form-perturbation theory is also dealt with. 相似文献
16.
Let (A,?) be a Banach algebra. Then for n∈?, A (2n) has 2 n Arens products. In this paper we study the relations between the Arens products on A (2n). Moreover, if P n (A) denotes the set of all Arens products on A (2n), for n∈?, we show that $P(A)=\bigcup_{n=1}^{\infty} P_{n}(A)$ is a ∧-semilattice. Also, we study P(A) as an infinite commutative semigroup and P(A)?{?} as a free semigroup generated by two elements. Then we investigate amenability and weak amenability for their semigroup Banach algebras. 相似文献
17.
18.
This article is concerned with a stochastic model of gene expression with distributed delay and degenerate diffusion. We transform the model with weak kernel case into an equivalent system through the linear chain technique. Since the diffusion matrix is of degenerate type, the uniform ellipticity condition is not satisfied. The Markov semigroup theory is used to obtain the existence and uniqueness of a stable stationary distribution. We prove the densities of the distributions of the solutions can converge in L1 to an invariant density. The existence of the stationary distribution implies stochastic weak stability. Numerical simulation is introduced to illustrate the analytical result. 相似文献
19.
António Malheiro 《Semigroup Forum》2009,78(3):450-485
In this paper we give a partial answer to the following question: does a large subsemigroup of a semigroup S with the finite combinatorial property finite derivation type (FDT) also have the same property? A positive answer is given for large ideals. As a consequence of this statement we prove that, given a finitely presented Rees matrix semigroup M[S;I,J;P], the semigroup S has FDT if and only if so does M[S;I,J;P]. 相似文献
20.
Prakit Jampachon Maliwan Saichalee R. P. Sullivan 《Southeast Asian Bulletin of Mathematics》2001,25(2):233-244
A semigroup S is factorisable if S = GE = EG where G is a subgroup of S and E is the set of idempotents in S; and S is locally factorisable if eSe is factorisable for every e E. In this paper, we unify and extend results which characterise when certain transformation semigroups defined on a set are (locally) factorisable, and we consider the corresponding problem for the semigroup of linear transformations of a vector space.To Yupaporn Kemprasit, mentor of semigroup theorists in Thailand1991 Mathematics Subject Classification: 20M20The third section of this paper formed part of an MSc supervised by the first author. She greatly appreciates the help of her supervisor in this work; and the first two authors are grateful for the assistance of the third author in the preparation of this paper. The third author also acknowledges the generous support of Centro de Mathematica, Universidade do Minho, Portugal, during his visit in July–August 2000 when the paper was completed. 相似文献