摘要:

AbstractTo include the pointfree case, the notion of a Cauchy map easily extends as the condition that the preimage of any regular Cauchy filter contains a regular Cauchy filter. This extension, however, can be unsatisfactory if the regular Cauchy filters are scarce or non‐existent, making the condition too weak, indeed sometimes even void. In this paper a variant of the notion, independent on the existence of any kind of filters, is studied: a homomorphism is called fully Cauchy if it lifts to the completions. This is generally stronger than, and in the spatial and metric cases it coincides with the previously mentioned property. Moreover, it is stable under localizatio

ISSN:0025-584X    

DOI:10.1002/mana.19971830102

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractIn this paper we prove subelliptic estimates for operators of the form Δx+λ2(x)Sin ℝN= ℝ xn× ℝ ym, where the operatorSis an elliptic integro ‐ differential operator in ℝNand λ is a nonnegative Lipschitz co

ISSN:0025-584X    

DOI:10.1002/mana.19971830103

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractAn elementary straightforward proof for the boundedness of pseudo ‐ differential operators of the Hörmander class ΨμI,δon weighted Besov ‐ Triebel spaces is given using a discrete characterization of function

ISSN:0025-584X    

DOI:10.1002/mana.19971830104

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractWe consider the eigenvalue problemfortϵ [0,b], wherean= |a|nsgna, aϵ ℝ, λ ϵ ℝ, the constants μ, vare real such that 0 ≤ μ0 which corresponds to the well‐known WKB‐approximation in the linear casen= 1, μ = 0. In the second part we investigate the asymptotic distribution of the eigenvalues in the general case of two ‐point boundary conditions and refine these results for the so called separated b

ISSN:0025-584X    

DOI:10.1002/mana.19971830105

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractNonlinear Riemann ‐ Hilbert problems (RHP) generalize two fundamental classical problems for complex analytic functions, namely: 1. the conformal mapping problem, and 2. the linear Riemann ‐ Hilbert problem. This paper presents new results on global existence for the nonlinear (RHP) in doubly connected domains with nonclosed restriction curves for the boundary data. More precisely, our nonlinear (RHP) is required to become „at infinity”︁, i.e., for solutions having large moduli, a linear (RHP) with variable coefficients. Global existence forq‐connected domains was already obtained in [9] for the special case that the restriction curves for the boundary data „at infinity”︁ coincide with straight lines corresponding to linear (RHP)‐s with special so‐called constant ‐ coefficient transversality boundary conditions. In this paper, the boundary conditions are much more general including highly nonlinear conditions for bounded solutions in the context of nontransversality. In order to prove global existence, we reduce the problem to nonlinear singular integral equations which can be treated by a degree theory of Fredholm ‐ quasiruled mappings specifically constructed for mappings defined by nonlinar pse

ISSN:0025-584X    

DOI:10.1002/mana.19971830106

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe notion of a period of a cusp form on GL(2,D(

ISSN:0025-584X    

DOI:10.1002/mana.19971830107

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractFor a real‐valued random variable whose distribution is the classical Cantor probability, then‐ quantization error and then‐ optimal quantization rules are calculated for every natural numbern. Moreover, the connection between the rate of convergence of the logarithms of the quantization errors forngoing to infinity and the Hausdorff dimension of the Cantor set is indi

ISSN:0025-584X    

DOI:10.1002/mana.19971830108

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractLet Φ(t) and Ψ(t) be the functions having the following representations Φ(t) = ∫ t0a(s)dsand Ψ(t) = ∫ t0b(s)ds, wherea(s) is a positive continuous function such that ∫ ∞1a(s)/s ds = + ∞ andb(s) is an increasing function such that lims→ ∞b(s) = + ∞. Then the following statements for the Hardy ‐ Littlewood maximal functionM f(x) are equivalent:1(i) there exist positive constantsc1ands0such that1(ii) there exist positi

ISSN:0025-584X    

DOI:10.1002/mana.19971830109

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

ISSN:0025-584X    

DOI:10.1002/mana.19971830110

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractWe give a necessary condition for the ideal class group of a CM‐field to be of exponent at most two. This condition enables us to drastically reduce the amount of relative class number computation for determination of the CM ‐ fields of some types (e. g. the imaginary cyclic non ‐quadratic number fields of 2 ‐ power degrees) whose ideal class groups are of exponents at most two. We also give a necessary condition for some quartic non ‐ CM ‐ fields to have class

ISSN:0025-584X    

DOI:10.1002/mana.19971830111

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY