共查询到20条相似文献,搜索用时 906 毫秒
1.
2.
K. Geetha 《Semigroup Forum》1999,58(2):207-221
Let V be a vector space of dimension n over a field K . Here we denote by Sn the set of all singular endomorphisms of V . Erdos [5], Dawlings [4] and Thomas J. Laffey [6] have shown that Sn is an idempotent generated regular semigroup. In this paper we apply the theory of inductive groupoids, in particular the construction of the idempotent generated regular semigroup given in §6 of [8] to detemine some combinatorial properties of the semigroup Sn . 相似文献
3.
Let G/H be an irreducible globally hyperbolic semisimple symmetric space, and let S ³ G be a subsemigroup containing H not isolated in S . We show that if So p 0 then there are H -invariant minimal and maximal cones C min ³ C max in the tangent space at the origin such that H exp C min ³ S ³ HZK (a)expC max . A double coset decomposition of the group G in terms of Cartan subspaces and the group H is proved. We also discuss the case where G/H is of Cayley type. 相似文献
4.
The topological interpretations of some of the algebraic properties of the semigroup Sn of singular endomorphisms of an n -dimensional vector space over K are discussed here. Since Sn is known to be an idempotent generated regular semigroup, we pay more attention to the topological properties of the set En of idempotents in Sn . The local structure of En is shown to be that of a C infinity-manifold and of a finite-dimensional vector bundle over the Grassmann manifolds. The topology of the biorder relations and sandwich sets are also discussed. 相似文献
5.
A finite semigroup S is said to be efficient if it can be defined by a presentation (A | R) with |R | -|A |=rank(H 2 (S )). In this paper we demonstrate certain infinite classes of both efficient and inefficient semigroups. Thus, finite abelian groups, dihedral groups D 2 n with n even, and finite rectangular bands are efficient semigroups. By way of contrast we show that finite zero semigroups and free semilattices are never efficient. These results are compared with some well-known results on the efficiency of groups. 相似文献
6.
Gabor frame sets for subspaces 总被引:1,自引:0,他引:1
This paper investigates Gabor frame sets in a periodic subset
\mathbb S\mathbb S of
\mathbb R\mathbb R. We characterize tight Gabor sets in
\mathbb S\mathbb S, and obtain some necessary/sufficient conditions for a measurable subset of
\mathbb S\mathbb S to be a Gabor frame set in
\mathbb S\mathbb S. We also characterize those sets
\mathbb S\mathbb S admitting tight Gabor sets, and obtain an explicit construction of a class of tight Gabor sets in such
\mathbb S\mathbb S for the case that the product of time-frequency shift parameters is a rational number. Our results are new even if
\mathbb S=\mathbb R\mathbb S=\mathbb R. 相似文献
7.
Assume that the elliptic operator L=div (A(x)∇) is L
p
-resolutive, p>1, on the unit disc
\mathbbD ì \mathbb R2\mathbb{D}\subset \mathbb {R}^{2}
. This means that the Dirichlet problem
$\left\{{l@{\quad}l}Lu=0&\mbox{in }\mathbb{D},\\[3pt]u=g&\mbox{on }\partial\mathbb{D}\right.$\left\{\begin{array}{l@{\quad}l}Lu=0&\mbox{in }\mathbb{D},\\[3pt]u=g&\mbox{on }\partial\mathbb{D}\end{array}\right. 相似文献
8.
Let S be a real interval with
, and
be a function satisfying
We show that if h is Lebesgue or Baire measurable, then there
exists
such that
That result is motivated by a question of E. Manstaviius.
Received: 11 February 2003 相似文献
9.
Chen-Lian Chuang Tsiu-Kwen Lee Cheng-Kai Liu Yuan-Tsung Tsai 《Israel Journal of Mathematics》2010,175(1):157-178
Let R be a prime ring and δ a derivation of R. Divided powers $
D_n ^{\underline{\underline {def.}} } \tfrac{1}
{{n!}}\tfrac{{d^n }}
{{dx^n }}
$
D_n ^{\underline{\underline {def.}} } \tfrac{1}
{{n!}}\tfrac{{d^n }}
{{dx^n }}
of ordinary differentiation d/dx form Hasse-Schmidt higher derivations of the Ore extension (skew polynomial ring) R[x; δ]. They have been used crucially but implicitly in the investigation of R[x; δ]. Our aim is to explore this notion. The following is proved among others: Let Q be the left Martindale quotient ring of R. It is shown that $
S^{\underline{\underline {def.}} } Q[x;\delta ]
$
S^{\underline{\underline {def.}} } Q[x;\delta ]
is a quasi-injective (R, R)-module and that any (R,R)-bimodule endomorphism of S can be uniquely expressed in the form
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