共查询到20条相似文献,搜索用时 31 毫秒
1.
Yu. A. Neretin 《Functional Analysis and Its Applications》2011,45(3):225-239
We construct spherical subgroups in infinite-dimensional classical groups G (usually they are not symmetric and their finite-dimensional analogs are not spherical). We present a structure of a semigroup
on double cosets L\G/L for various subgroups L in G; these semigroups act in spaces of L-fixed vectors in unitary representations of G. We also obtain semigroup envelops of groups G generalizing constructions of operator colligations. 相似文献
2.
Maximal semigroups dominated by a 0–1 matrix of a certain type are determined. The 0–1 matrices that dominate maximal bounded
and maximal commuting semigroups are given. Also semigroup modules over maximal semigroups dominated by a 0–1 matrix are discussed. 相似文献
3.
Haixuan Yang 《Semigroup Forum》2002,64(3):397-424
In this paper, varieties of completely regular semigroups are studied. This paper is divided into six sections. Section 1
contains an introduction to varieties of completely regular semigroups and preliminaries. Most of the notation needed in this
paper is given. In Section 2, the operators \La ( ) and \Ra ( ) on the lattice of subvarieties of varieties of completely regular semigroups are investigated. In Section 3, some further
properties of the operators \La ( ) and \Ra ( ) are given. In Section 4, the semigroups generated by various subset of some operators are considered. In Section 5, the
operators \La ( ) and \Ra ( ) are used in finding the join of two given varieties. The word problem for free objects in the variety OLBG is considered in Section 6 using the operator \La ( ) .
June 1, 1999 相似文献
4.
We investigate in detail the mapping properties of the maximal operator associated with the heat-diffusion semigroup corresponding
to expansions with respect to multi-dimensional standard Laguerre functions . Our interest is focused on the situation when at least one coordinate of the type multi-index α is smaller than 0. For such parameters α the Laguerre semigroup does not satisfy the general theory of semigroups, and the behavior of the associated maximal operator
on L
p
spaces is found to depend strongly on both α and the dimension.
A. Nowak was supported in part by MNiSW Grant N201 054 32/4285. 相似文献
5.
Let S be a regular semigroup, and let a ∈ S . Then a variant of S with respect to a is a semigroup with underlying set S and multiplication \circ defined by x \circ y = xay . In this paper, we characterise the regularity preserving elements of regular semigroups; these are the elements a such that (S,\circ) is also regular. Hickey showed that the set of regularity preserving elements can function as a replacement for the unit
group when S does not have an identity. As an application, we characterise the regularity preserving elements in certain Rees matrix
semigroups. We also establish connections with work of Loganathan and Chandrasekaran, and with McAlister's work on inverse
transversals in locally inverse semigroups. We also investigate the structure of arbitrary variants of regular semigroups
concentrating on how the local structure of a semigroup affects the structure of its variants.
May 24, 1999 相似文献
6.
This paper studies semigroups of operators on Hardy and Dirichlet spaces whose generators are differential operators of order greater than one. The theory of forms is used to provide conditions for the generation of semigroups by second order differential operators. Finally, a class of more general weighted Hardy spaces is considered and necessary and sufficient conditions are given for an operator of the form \(f \mapsto Gf^{(n_0)}\) (for holomorphic G and arbitrary \(n_0\)) to generate a semigroup of quasicontractions. 相似文献
7.
Norman R. Reilly 《Semigroup Forum》2012,84(1):176-199
In a manner similar to the construction of the fundamental group of a connected graph, this article introduces the construction
of a fundamental semigroup associated with a bipartite graph. This semigroup is a 0-direct union of idempotent generated completely
0-simple semigroups. The maximal nonzero subgroups are the corresponding fundamental groups of the connected components. Adding
labelled edges to the graph leads to a more general completely 0-simple semigroup. The basic properties of such semigroups
are examined and they are shown to have certain universal properties as illustrated by the fact that the free completely simple
semigroup on n generators and its idempotent generated subsemigroup appear as special cases. 相似文献
8.
Elton Pasku 《Semigroup Forum》2011,83(1):75-88
We prove that the category of Clifford semigroups and prehomomorphisms CSP\mathcal{CSP} is isomorphic to a certain subcategory of the category of diagrams over groups. Under this isomorphism, Clifford semigroups
are identified with certain functors. As an application of the isomorphism theorem, we show that the category with objects
commutative inverse semigroups having the same semilattice of idempotents and with morphisms, the inverse semigroup homomorphisms
that fix the semilattice, imbeds into a category of right modules over a certain ring. Also we find a very close relationship
between the cohomology groups of a commutative inverse monoid and the cohomology groups of the colimit group of the functor
giving the monoid. 相似文献
9.
Marcel Jackson 《Semigroup Forum》2002,64(2):297-324
We show how to construct all ``forbidden divisors' for the pseudovariety of not inherently nonfinitely based finite semigroups. Several other results concerning finite semigroups that generate an inherently
nonfinitely based variety that is miminal amongst those generated by finite semigroups are obtained along the way. For example,
aside from the variety generated by the well known six element Brandt monoid \tb , a variety of this type is necessarily generated by a semigroup with at least 56 elements (all such semigroups with 56 elements
are described by the main result).
September 23, 1999 相似文献
10.
We find strong relationships between the zero-divisor graphs of apparently disparate kinds of nilpotent-free semigroups by introducing the notion of an Armendariz map between such semigroups, which preserves many graph-theoretic invariants. We use it to give relationships between the zero-divisor graph of a ring, a polynomial ring, and the annihilating-ideal graph. Then we give relationships between the zero-divisor graphs of certain topological spaces (so-called pearled spaces), prime spectra, maximal spectra, tensor-product semigroups, and the semigroup of ideals under addition, obtaining surprisingly strong structure theorems relating ring-theoretic and topological properties to graph-theoretic invariants of the corresponding graphs. 相似文献
11.
12.
Let τ be an equivalence relation on a semigroup. We introduce τ-congruence-free semigroups, extending the notion of congruence-free semigroups, and classify all completely regular semigroups
which are τ-congruence-free, where τ is one of Green’s relations H,L\mathcal{H},\mathcal{L} and D\mathcal{D} respectively. Taking τ as H\mathcal{H} as well as D\mathcal{D}, this settles two open problems posed by M. Petrich and N.R. Reilly. 相似文献
13.
Yevhen Zelenyuk 《Semigroup Forum》2001,63(3):457-465
A semigroup S is called an absolute coretract if for any continuous homomorphism f from a compact Hausdorff right topological semigroup T onto a compact Hausdorff right topological semigroup containing S algebraically there exists a homomorphism g \colon S→ T such that f\circ g=id
S
. The semigroup β\ben contains isomorphic copies of any countable absolute coretract. In this article we define a class C of semigroups of idempotents each of which is a decreasing chain of rectangular semigroups. It is proved that every semigroup
from C is an absolute coretract and every finite semigroup of idempotents, which is an absolute coretract, belongs to C .
July 25, 2000 相似文献
14.
Yu. A. Kordyukov 《Acta Appl Math》1991,23(3):223-260
This paper is devoted to some of the properties of uniformly elliptic differential operators with bounded coefficients on manifolds of bounded geometry in L
pspaces. We prove the coincidence of minimal and maximal extensions of an operator of a considered type with a positive principal symbol, the existence of holomorphic semigroup, generated by it, and the estimates of L
p-norms of the operators of this semigroup. Some spectral properties of such operators in L
pspaces are also studied. 相似文献
15.
We precisely evaluate Bellman-type functions for the dyadic maximal operator on \(\mathbb {R}^{n}\) and of maximal operators on martingales related to local Lorentz-type estimates. Using a type of symmetrization principle, introduced for the dyadic maximal operator in earlier works of the authors, we precisely evaluate the supremum of the Lorentz quasinorm of the maximal operator on a function \(\phi \) when the integral of \(\phi \) is fixed and also the same Lorentz quasinorm of \(\phi \) is fixed. Also we find the corresponding supremum when the integral of \(\phi \) is fixed and several weak type conditions are given. 相似文献
16.
We investigate two systematic constructions of inverse-closed subalgebras of a given Banach algebra or operator algebra $\ensuremath {\mathcal {A}}We investigate two systematic constructions of inverse-closed subalgebras of a given Banach algebra or operator algebra A\ensuremath {\mathcal {A}}, both of which are inspired by classical principles of approximation theory. The first construction requires a closed derivation
or a commutative automorphism group on A\ensuremath {\mathcal {A}} and yields a family of smooth inverse-closed subalgebras of A\ensuremath {\mathcal {A}} that resemble the usual H?lder–Zygmund spaces. The second construction starts with a graded sequence of subspaces of A\ensuremath{\mathcal{A}} and yields a class of inverse-closed subalgebras that resemble the classical approximation spaces. We prove a theorem of
Jackson–Bernstein type to show that in certain cases both constructions are equivalent. 相似文献
17.
B. Steinberg 《Semigroup Forum》2001,62(1):1-40
This paper considers the algorithmic problems of decidability (of membership), decidability of pointlikes and idempotent pointlikes, and hyperdecidability for joins of pseudovarieties of semigroups. In particular, we show that if \pv V\subseteq \pv J has a decidable word problem for its semigroup of implicit operations and \pv W is a hyperdecidable pseudovariety of completely regular semigroups, then \pv V \vee \pv W is hyperdecidable. The same holds for pointlikes and idempotent pointlikes. In fact by careful analysis of the arguments involved, one can show that \pv J \vee \pv G is definable by a recursive set of pseudoidentities, involving only implicit operations built up from words and the () ω -1 operator. Since Trotter and Volkov have proven that \pv J \vee \pv G is not finitely based, we feel that this is a satisfactory answer to the pseudoidentity basis problem for \pv J \vee \pv G , and in fact this basis gives an, albeit unbounded, membership algorithm. 相似文献
18.
Francisco Luis Rocha Pimentel 《Geometriae Dedicata》2001,85(1-3):125-134
We present a new result on the geometry of nonhyperelliptic curves; namely, the intersection divisors of a canonically embedded curve C with its osculating spaces at a point P, not considering the intersection at P, can only vary in dimensions given by the Weierstrass semigroup of the curve C at P. We obtain, under a reasonable geometrical hypothesis, monomial bases for the spaces of higher-order regular differentials. We also give a sufficient condition on the Weierstrass semigroup of C at P in order for this geometrical hypothesis to be true. Finally, we give examples of Weierstrass semigroups satisfying this condition. 相似文献
19.
C. Robinson Edward Raja 《Journal of Theoretical Probability》1999,12(2):561-569
Let G be a connected reductive Lie group and K be a maximal compact subgroup of G. We prove that the semigroup of all K-biinvariant probability measures on G is a strongly stable Hungarian semigroup. Combining with the result [see Rusza and Szekely(9)], we get that the factorization theorem of Khinchin holds for the aforementioned semigroup. We also prove that certain subsemigroups of K-biinvariant measures on G are Hungarian semigroups when G is a connected Lie group such that Ad G is almost algebraic and K is a maximal compact subgroup of G. We also prove a p-adic analogue of these results. 相似文献
20.
《代数通讯》2013,41(6):2461-2479
Superabundant semigroups are generalizations of completely regular semigroups written the class of abundant semigroups. It has been shown by Fountain that an abundant semigroup is superabundant if and only if it is a semilattice of completely J *-simple semigroups. Reilly and Petrich called a semigroup S cryptic if the Green's relation H is a congruence on S. In this paper, we call a superabundant semigroup S a regular crypto semigroup if H * is a congruence on S such that S/H * is a regular band. It will be proved that a superabundant semigroup S is a regular crypto semigroup if and only if S is a refined semilattice of completely J *-simple semigroups. Thus, regular crypto semigroups are generalization of the cryptic semigroups as well as abundant semigroups. 相似文献