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Träfflista för sökning "(hsv:(NATURVETENSKAP) hsv:(Matematik) hsv:(Matematisk analys)) srt2:(1990-1999)"

Search: (hsv:(NATURVETENSKAP) hsv:(Matematik) hsv:(Matematisk analys)) > (1990-1999)

  • Result 1-10 of 422
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1.
  • Svanström, Mattias (author)
  • Ternary Codes with Weight Constraints
  • 1999
  • Doctoral thesis (other academic/artistic)abstract
    • We study the problem of maximizing the size of a ternary block code with given length and minimum Hamming distance. The problem is further restricted in two different ways. Either we require all codewords to have constant Hamming weight, or we require all codewords to have constant composition. We let the alphabet consist of the symbols zero, one and two. In a constant-composition code the number of zeros, the number of ones and the number of twos in each codeword are fixed, while in a constant-weight code only the total number of ones and twos in each codeword is fixed.For both code classes several upper bounds are presented. We give a number of constructions of codes that meet the upper bounds. A construction of perfect ternary constant-weight codes with minimum distance three is presented. We have also compiled tables of the best possible upper and lower bounds on the code size.
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2.
  • Albeverino, S., et al. (author)
  • Pseudo-Differential Operators with Point Interactions
  • 1997
  • In: Letters in Mathematical Physics. - 0377-9017 .- 1573-0530. ; 41, s. 79-92
  • Journal article (peer-reviewed)abstract
    • Point interactions for pseudo-differential operators are studied. Necessary and sufficient conditions for a pseudo-differential operator to have nontrivial point perturbations are given. The results are applied to the construction of relativistic spin zero Hamiltonians with point interactions.
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3.
  • Albeverio, S., et al. (author)
  • Finite rank perturbations and distribution theory
  • 1999
  • In: Proceedings of the American Mathematical Society. - 0002-9939 .- 1088-6826. ; 127:4, s. 1151-1161
  • Journal article (peer-reviewed)abstract
    • Perturbations AT of a selfadjoint operator A by symmetric finite rank operators T from H2A) to H-2(A) are studied. The finite dimensional family of selfadjoint extensions determined by AT is given explicitly.
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4.
  • Albeverio, S., et al. (author)
  • Rank one perturbations of not semibounded operators
  • 1997
  • In: Integral equations and operator theory. - 0378-620X .- 1420-8989. ; 27:4, s. 379-400
  • Journal article (peer-reviewed)abstract
    • Rank one perturbations of selfadjoint operators which are not necessarily semibounded are studied in the present paper. It is proven that such perturbations are uniquely defined, if they are bounded in the sense of forms. We also show that form unbounded rank one perturbations can be uniquely defined if the original operator and the perturbation are homogeneous with respect to a certain one parameter semigroup. The perturbed operator is defined using the extension theory for symmetric operators. The resolvent of the perturbed operator is calculated using Krein's formula. It is proven that every rank one perturbation can be approximated in the operator norm. We prove that some form unbounded perturbations can be approximated in the strong resolvent sense without renormalization of the coupling constant only if the original operator is not semibounded. The present approach is applied to study first derivative and Dirac operators with point interaction, in one dimension
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5.
  • Albeverio, S., et al. (author)
  • Symmetries of Schrödinger operator with point interactions
  • 1998
  • In: Letters in Mathematical Physics. - 0377-9017 .- 1573-0530. ; 45, s. 33-47
  • Journal article (peer-reviewed)abstract
    • The transformations of all the Schrödinger operators with point interactions in dimension one under space reflection P, time reversal T and (Weyl) scaling Wλ are presented. In particular, those operators which are invariant (possibly up to a scale) are selected. Some recent papers on related topics are commented upon
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8.
  • Fällström, Anders (author)
  • Maximal idels in A(Omega)
  • 1999
  • In: Conemporary Mathematics. ; 222, s. 173-179
  • Journal article (peer-reviewed)
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  • Result 1-10 of 422
Type of publication
journal article (263)
conference paper (54)
other publication (24)
doctoral thesis (22)
reports (19)
licentiate thesis (19)
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book (9)
book chapter (9)
editorial collection (2)
editorial proceedings (1)
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Type of content
peer-reviewed (318)
other academic/artistic (95)
pop. science, debate, etc. (9)
Author/Editor
Persson, Lars-Erik (79)
Maligranda, Lech (45)
Euler, Norbert (36)
Wall, Peter (17)
Wennberg, Bernt, 196 ... (16)
Gyllenberg, Mats (16)
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Koski, Timo (14)
Lennerstad, Håkan (11)
Kurasov, Pavel (11)
Bergström, Lars (10)
Euler, Marianna (10)
Strömberg, Thomas (9)
Ericsson, Stefan (9)
Lundberg, Lars (8)
Barza, Sorina (7)
Pecaric, Josip (6)
Andersson, Mats, 195 ... (6)
Lukkassen, Dag (6)
Fällström, Anders (6)
Barza, Ilie (6)
Albeverio, S. (5)
Sjögren, Peter, 1948 (5)
Näslund, Reinhold (5)
Kruglyak, Natan (5)
Thunberg, Hans, 1956 ... (5)
Byström, Johan (5)
Dencker, Nils (5)
Lundh, Torbjörn, 196 ... (4)
Lundberg, Staffan (4)
Svensson, Olof (4)
Kiselman, Christer (4)
Kufner, Alois (4)
Ödling, Per (3)
Börjesson, Per Ola (3)
Cheng, Yuanji (3)
Ekblom, Håkan (3)
Asekritova, Irina (3)
Carro, Maria J. (3)
Asratian, Armen (3)
Backlund, Ulf (3)
Grip, Niklas (3)
Heinig, Hans P. (3)
Burenkov, Victor (3)
Lithner, Johan (3)
Peetre, Jaak (3)
Carlsson, Svante (3)
Diekmann, Odo (3)
Nikolova, Ljudmila I ... (3)
Thieme, Horst R. (3)
Duarte, L.G.S. (3)
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University
Luleå University of Technology (293)
Chalmers University of Technology (50)
University of Gothenburg (48)
Linköping University (24)
Umeå University (17)
Lund University (17)
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Blekinge Institute of Technology (13)
Uppsala University (7)
Stockholm University (6)
Royal Institute of Technology (5)
Linnaeus University (4)
Mid Sweden University (2)
VTI - The Swedish National Road and Transport Research Institute (2)
Mälardalen University (1)
Jönköping University (1)
Karlstad University (1)
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Language
English (405)
Russian (9)
Swedish (7)
French (1)
Research subject (UKÄ/SCB)
Natural sciences (422)
Engineering and Technology (18)
Social Sciences (3)
Medical and Health Sciences (1)
Humanities (1)

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