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本文研究了三维Minkowski空间中直线汇的一些性质,特别是关于类时线汇的性质.讨论了线汇基本元素的存在性,并证明了关于三维Minkowski空间中类时线汇的配分参数的一个结果,推广了苏步青1927年的—个成果. 相似文献
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Directed complete partially ordered sets (dcpos, for short) play an important role in domain theory. The aim of this paper is to characterise natural congruences of dcpos. We also show that the kernels of dcpo maps, that is, directed join-preserving maps between dcpos are not necessarily natural dcpo congruences. Then we characterise dcpo maps whose kernels are natural dcpo congruences. Finally, we prove the Decomposition and Isomorphism Theorems for dcpo maps. 相似文献
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纯正半群上的同余扩张(一) 总被引:1,自引:1,他引:0
刻划半群上的同余及其扩张是半群的代数理论中的一个非常重要的课题.本文讨论了带上的同余的正规性和不变性以及在其Hall半群上的扩张,从同余扩张的角度刻划了带上的同余的性质,给出了扩张的极大、极小同余的描述. 相似文献
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Loday and Ronco introduced the notion of a trioid and constructed the free trioid of rank 1. This paper is devoted to the study of congruences on trioids. We characterize the least dimonoid congruences and the least semigroup congruence on the free (commutative, rectangular) trioid. 相似文献
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In this paper, some properties of good homomorphic images of abundant semigroups with a multiplicative quasi-adequate transversal
are obtained. After that, good congruences on a class of abundant semigroups with such transversals are studied. We characterize
the good congruences by using the so-called good congruence triple. Furthermore, we prove that any good congruence on a class
of abundant semigroups with such transversals can be constructed by the good congruence triple. 相似文献
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设S是有向序半群,本文给出了S上的一类正则同余,称为强序同余的定义及性质.证明了S的强序同余是强正则同余,但反之不成立.同时证明了强序同余格SOC(S)是S的同余格C(S)关于通常集合的交和传递积的V-完备的分配子格. 相似文献
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It is well known that the smallest semilattice congruence can be described via filters. We generalise this result to the smallest
left (right) normal band congruences and also to arbitrary semilattice (left normal band, right normal band) congruences,
describing them all via filters. To achieve this, we introduce filters relative to arbitrary quasiorders on a semigroup (traditional
filters are filters relative to the smallest negative operation-compatible quasiorder). We study congruences which can be
described via filters. We show that the lattice of semilattice (left normal band, right normal band) congruences is a homomorphic
image of the lattice of negative (right negative, left negative) operation-compatible quasiorders. 相似文献
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In this paper we study the congruences of *-regular semigroups, involution semigroups in which every element is p-related
to a projection (an idempotent fixed by the involution). The class of *-regular semigroups was introduced by Drazin in 1979,
as the involutorial counterpart of regular semigroups. In the standard approach to *-regular semigroup congruences, one ,starts
with idempotents, i.e. with traces and kernels in the underlying regular semigroup, builds congruences of that semigroup,
and filters those congruences which preserve the involution. Our approach, however, is more evenhanded with respect to the
fundamental operations of *-regular semigroups. We show that idempotents can be replaced by projections when one passes from
regular to *-regular semigroup congruences. Following the trace-kernel balanced view of Pastijn and Petrich, we prove that
an appropriate equivalence on the set of projections (the *-trace) and the set of all elements equivalent to projections (the
*-kernel) fully suffice to reconstruct an (involution-preserving) congruence of a *-regular semigroup. Also, we obtain some
conclusions about the lattice of congruences of a *-regular semigroup.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
10.
We present some identities and congruences for the general partition function p r (n). In particular, we deduce some known identities for Ramanujan’s tau function and find simple proofs of Ramanujan’s famous partition congruences for modulo 5 and 7. Our emphasis throughout this paper is to exhibit the use of Ramanujan’s theta functions to generate identities and congruences for general partition function. 相似文献
11.
Robert F. Tichy 《Semigroup Forum》1979,18(1):371-380
In this paper we study the algebra of polynomial functions over a monoid (S,.,e). We consider the congruences and a natural
binary relation on this algebra of polynomial functions in several variables. 相似文献
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正则半群上的矩形群同余 总被引:1,自引:0,他引:1
文[1]中PetrichM定义了同余的核与迹,用它们描述了逆半群上的同余,Gomes在文[2]中定义了同余的核与超迹并描述了正则半群上的R-幂单(R-unipo-tent)同余,本文利用同余的核与超迹描述正则半群上的另一类重要同余,即矩形群同余. 相似文献
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We study four types of equational definability of factor congruences in varieties with \({\vec{0}}\) and \({\vec{1}}\). The paper completes the work of a previous paper on left equational definability of factor congruences. 相似文献
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The motivation mainly comes from the conditions of congruences to be regular that are of importance and interest in ordered semigroups. In 1981, Sen has introduced the concept of the Γ-semigroups. We can see that any semigroup can be considered as a Γ-semigroup. In this paper, we introduce and characterize the concept of the regular congruences on ordered Γ-semigroups and prove the following statements on an ordered Γ-semigroup M : (1) Every ordered semilattice congruences is a regular congruence. (2) There exists the least regular order on the Γ-semigroup M/ρ with respect to a regular congru- ence ρ on M . (3) The regular congruences are not ordered semilattice congruences in general. 相似文献
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带逆断面的正则半群是一类重要的正则半群.就带逆断面的正则半群类引入强模糊同余的概念,进而用所谓的强模糊同余三元组抽象地刻画带逆断面的正则半群上的强模糊同余. 相似文献
20.
罗从文 《数学物理学报(B辑英文版)》2011,31(3):1113-1122
Algebras whose congruences are permutable were investigated by a number of authors in the literature. In this paper, we study the symmetric extended MS-algebras whose congruences are permutable. Some results obtained by Jie Fang on symmetric extended De Morgan algebras are generalized. 相似文献