ISSN:1607-3606    

DOI:10.1080/16073606.1992.9631701

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The note gives an efficient method to compute Green's function for Laplace's operator in an arbitrary rectangle.

ISSN:1607-3606    

DOI:10.1080/16073606.1992.9631702

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We define a morita context for near-rings and subsequently a morita near-ring. Any near-ring can be considered as a morita context for near-rings, and the corresponding morita near-ring is just the 2 x 2 matrix near-ring over the near-ring. We also determine the relationships between the ideals of a morita context and the ideals of a morita near-ring.

ISSN:1607-3606    

DOI:10.1080/16073606.1992.9631703

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Letdbe a positive integer, andFbe a field of characteristic zero. Suppose that for each positive integern,In, is aGLn,(F)- invariant of forms of degreedin x1, …,xn, over F. We call {In} anadditive family of invariantsifIp+q(f⊥g) =Ip(f).Iq(g) wheneverf;gare forms of degreedoverFinxl, …,xp; …,xqrespectively, and where (f⊥g)(xl, …,xp+q) =f(x1, …,xp,) +g(xp+1, …,xp+q). It is well-known that the family of discriminants of the quadratic forms is additive. We prove that in odd degree d each invariant in an additive family must be a constant. We also give an example in each even degree d of a nontrivial family of invariants of the forms of degree d. The proofs depend on thesymbolic methodfor representing invariants of a form, which we review.

ISSN:1607-3606    

DOI:10.1080/16073606.1992.9631704

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Thetechniquesfor discussing linear differential operators in left definite spaces, developed earlier for regular fourth order and singular second order operators, are applied the Legendre type operator. It is shown that the operator, with its domain merely restricted to the new space, remains self-adjoint and has the same spectrum, inverse and spectral resolution (an eigenfunction expansion) as the originalL2operator.

ISSN:1607-3606    

DOI:10.1080/16073606.1992.9631705

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Given graphsFandGand a nonnegative integerk, a map Π:V(F) → + {lm…,k} is a -Gk-colouring ofFif the subgraphs induced by each colour class do not containGas an induced subgraph;Fis -Gk-chromaticifFhas a -Gk-colouring but no -G(k—1)-colouring. Further, we sayFisuniquely-Gk-colourableif and only ifFis -Gk-chromatic and, up to a permutation of colours, it has only one -Gk-colouring. Such notions are extensions of the well known corresponding definitions from chromatic theory. In a previous paper (J. Graph. Th. 11 (1987), 87–99), the authors conjectured that for all graphs G of order at least two and all nonnegative integers k there exist uniquely -Gk-colourable graphs. We show here that the conjecture holds wheneverGor its complement is 2-connected.

ISSN:1607-3606    

DOI:10.1080/16073606.1992.9631706

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Using a general definition of a regularity for rings,F- andF- qausi-ideals of a ring are defined. These concepts are shown to be generalizations of ideals or one-sided ideals of a ring. An F-semi primeF—(F-quasi-) ideal of a ringRis also defined.F-regular rings are characterized in terms of F-semi primeF- (F-quasi-) ideals for a large class of polynomial regularities including some well known regularities. A more general characterization of the prime radical β(R) of a ring are given in terms ofF—(F-quasi-) ideals.

ISSN:1607-3606    

DOI:10.1080/16073606.1992.9631707

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A simple remark on the localization of the extreme points of the unit ball of the dual of the space of weakly continuous functions or weak* continuous functions give some new insight on these spaces and simplifies proofs in [ADLR 92] and [LO 91].

ISSN:1607-3606    

DOI:10.1080/16073606.1992.9631708

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:1607-3606    

DOI:10.1080/16073606.1992.9631709

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:1607-3606    

DOI:10.1080/16073606.1992.9631700

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor