摘要:

AbstractIn this paper we consider the finite section method for the solution of the double layer potential equation corresponding to Laplace's equation in a three‐dimensional polyhedron. We prove the stability of our method in case of special polyhedron

ISSN:0025-584X    

DOI:10.1002/mana.19921570102

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractRegular leftK‐sequentially complete quasi‐metric spaces are characterized. We deduce that these spaces are complete Aronszajn and that every metrizable space admitting a leftK‐sequentially complete quasi‐metric is completely metrizable. We also characterize quasi‐metric spaces having a quasi‐metric leftK‐sequential completion in terms of certain bases of co

ISSN:0025-584X    

DOI:10.1002/mana.19921570103

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

ISSN:0025-584X    

DOI:10.1002/mana.19921570104

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractIn this paper we give criteria for limitedness inC(K)‐spaces and discuss the Gelfand‐Phillips‐property. We show that the Gelfand‐Phillips‐property is not a three‐space‐property, thatl1⊄Xdoes not imply the Gelfand‐Phillips‐property ofXand that the Gelfand‐Phillips‐property of a spaceXdoes not imply that the dual unit ball contains aw*‐sequentially precompact subset whi

ISSN:0025-584X    

DOI:10.1002/mana.19921570105

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractA class of infinitesimal generatorsAof strongly continuous nonnegative contraction semigroups in a subspace ofC[0, 1] is introduced. It contains the class of generators of regular gap diffusions. A construction of the Markov processXgenerated byAgives some stochastic interpretations of the integral term which appears inA. The infinitesimal generator of the time reversal ofX(with respect to its life time) is explicitly given. It belongs to the introduced class of generators too. Thus, the considered class is invariant under this transformation. Two examples, the time reversal of gap diffusions with nonlocal boundary conditions and the time reversal of processes with Levy‐measure, complete the not

ISSN:0025-584X    

DOI:10.1002/mana.19921570106

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

ISSN:0025-584X    

DOI:10.1002/mana.19921570107

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractUsing the distances of a pointxto two convex sets we obtain an upper estimation of the distance ofxto the intersection of these two sets. Applications to the intersection of point‐to‐set mappings are gi

ISSN:0025-584X    

DOI:10.1002/mana.19921570108

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

ISSN:0025-584X    

DOI:10.1002/mana.19921570109

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractDie Arbeit enthält eine ausführliche Darlegung der in der Bemerkung [2] angekündigten Resultate. Sie ist stark beeinflußt von den langjährigen Forschungen M. G. Kreins über verallgemeinerte Resolventen und Resolventenmatrizen und stellt eine Weiterentwicklung derselben dar. Wesentlich wird auf Brodskii's Beitrag zur Theorie unitärer Operatorknoten zurückgegriffen. Das zentrale Resultat der Arbeit ist Theorem 2, welches eine Formel zur Beschreibung der Streumatrizen aller unitären Erweiterungen eines vorgegebenen isometrischen Operators im Hilbertraum liefert. Aus diesem Resultat werden einige aus der Literatur bekannte klassische Spezialfälle wie etwa die Formel von H. Langer he

ISSN:0025-584X    

DOI:10.1002/mana.19921570110

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractCertain norm related functions of linear operators are considered in the very general setting of not necessarily continuous linear operators in normed spaces. These are shown to be closely related to the theory of precompact, strictly cosingular and a class of Φ−type operators in addition to having applications to perturbation theory. We also obtain some basic continuity and precompactness properties of linear operators in normed spaces which are expressed in terms of the functions under considerati

ISSN:0025-584X    

DOI:10.1002/mana.19921570111

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY