Boundary value problems in time for wave equations on RN

Let Lλ denote the linear operator associated with the radially symmetric form of the wave operator ∂t2−Δ+λ together with the side conditions of decay to zero as r=‖x‖→+∞ and T-periodicity in time. Thus Lλω=ωtt−(ωrr+N−1rωr)+λω, when there are N space variables. For δ,R,T>0 let DT,R=(0,T)×(R,+∞) an...

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Main Authors: M. W. Smiley, A. M. Fink
Format: Article
Language:English
Published: Wiley 1990-01-01
Series:International Journal of Mathematics and Mathematical Sciences
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Online Access:http://dx.doi.org/10.1155/S0161171290000886
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author M. W. Smiley
A. M. Fink
author_facet M. W. Smiley
A. M. Fink
author_sort M. W. Smiley
collection DOAJ
description Let Lλ denote the linear operator associated with the radially symmetric form of the wave operator ∂t2−Δ+λ together with the side conditions of decay to zero as r=‖x‖→+∞ and T-periodicity in time. Thus Lλω=ωtt−(ωrr+N−1rωr)+λω, when there are N space variables. For δ,R,T>0 let DT,R=(0,T)×(R,+∞) and Lδ2(D) denote the weighted L2 space with weight function exp(δr). It is shown that Lλ is a Fredholm operator from dom(Lλ)⊂L2(D) onto Lδ2(D) with non-negative index depending on λ. If [2πj/T]2<λ≤[2π(j+1)/T]2 then the index is 2j+1. In addition it is shown that Lλ has a bounded partial inverse Kλ:Lδ2(D)→Hδ1(D)⋂Lδ∞(D), with all spaces weighted by the function exp(δr). This provides a key ingredient for the analysis of nonlinear problems via the method of alternative problems.
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spelling doaj-art-85ffd6604e2446ebbd162965cd688c692025-08-20T02:08:54ZengWileyInternational Journal of Mathematics and Mathematical Sciences0161-17121687-04251990-01-0113462564410.1155/S0161171290000886Boundary value problems in time for wave equations on RNM. W. Smiley0A. M. Fink1Department of Mathematics, Iowa State University, Ames 50011, Iowa, USADepartment of Mathematics, Iowa State University, Ames 50011, Iowa, USALet Lλ denote the linear operator associated with the radially symmetric form of the wave operator ∂t2−Δ+λ together with the side conditions of decay to zero as r=‖x‖→+∞ and T-periodicity in time. Thus Lλω=ωtt−(ωrr+N−1rωr)+λω, when there are N space variables. For δ,R,T>0 let DT,R=(0,T)×(R,+∞) and Lδ2(D) denote the weighted L2 space with weight function exp(δr). It is shown that Lλ is a Fredholm operator from dom(Lλ)⊂L2(D) onto Lδ2(D) with non-negative index depending on λ. If [2πj/T]2<λ≤[2π(j+1)/T]2 then the index is 2j+1. In addition it is shown that Lλ has a bounded partial inverse Kλ:Lδ2(D)→Hδ1(D)⋂Lδ∞(D), with all spaces weighted by the function exp(δr). This provides a key ingredient for the analysis of nonlinear problems via the method of alternative problems.http://dx.doi.org/10.1155/S0161171290000886wave equationradial symmetryboundary value problemeigenvalue problemHilbert spaceweighted Sobolev spaceFredholm operatorLaplace transformBessel functions.
spellingShingle M. W. Smiley
A. M. Fink
Boundary value problems in time for wave equations on RN
International Journal of Mathematics and Mathematical Sciences
wave equation
radial symmetry
boundary value problem
eigenvalue problem
Hilbert space
weighted Sobolev space
Fredholm operator
Laplace transform
Bessel functions.
title Boundary value problems in time for wave equations on RN
title_full Boundary value problems in time for wave equations on RN
title_fullStr Boundary value problems in time for wave equations on RN
title_full_unstemmed Boundary value problems in time for wave equations on RN
title_short Boundary value problems in time for wave equations on RN
title_sort boundary value problems in time for wave equations on rn
topic wave equation
radial symmetry
boundary value problem
eigenvalue problem
Hilbert space
weighted Sobolev space
Fredholm operator
Laplace transform
Bessel functions.
url http://dx.doi.org/10.1155/S0161171290000886
work_keys_str_mv AT mwsmiley boundaryvalueproblemsintimeforwaveequationsonrn
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