000476292 001__ 476292 000476292 005__ 20250715175534.0 000476292 0247_ $$2arXiv$$aarXiv:1806.06307 000476292 0247_ $$2doi$$a10.1007/s00605-022-01702-4 000476292 0247_ $$2datacite_doi$$a10.3204/PUBDB-2022-01667 000476292 0247_ $$2WOS$$aWOS:000797260800002 000476292 0247_ $$2openalex$$aopenalex:W2808479512 000476292 037__ $$aPUBDB-2022-01667 000476292 041__ $$aEnglish 000476292 082__ $$a510 000476292 088__ $$2arXiv$$aarXiv:1806.06307 000476292 1001_ $$0P:(DE-HGF)0$$aFeichtinger, Hans G.$$b0 000476292 245__ $$aThe inner kernel theorem for a certain Segal algebra 000476292 260__ $$aWien [u.a.]$$bSpringer$$c2022 000476292 3367_ $$2DRIVER$$aarticle 000476292 3367_ $$2DataCite$$aOutput Types/Journal article 000476292 3367_ $$0PUB:(DE-HGF)16$$2PUB:(DE-HGF)$$aJournal Article$$bjournal$$mjournal$$s1673964362_11678 000476292 3367_ $$2BibTeX$$aARTICLE 000476292 3367_ $$2ORCID$$aJOURNAL_ARTICLE 000476292 3367_ $$00$$2EndNote$$aJournal Article 000476292 520__ $$aThe Segal algebra $\mathbf{S}_{0}(G)$ is well defined for arbitrary locally compact Abelian Hausdorff (LCA) groups $G$. It is a Banach space that exhibits a kernel theorem similar to the well-known Schwartz kernel theorem. Specifically, we call this characterization of the continuous linear operators from $\mathbf{S}_{0}(G_{1})$ to $\mathbf{S}'_{0}(G_{2})$ by generalized functions in $\mathbf{S}'_{0}(G_{1} \times G_{2})$ the 'outer kernel theorem'. The main subject of this paper is to formulate what we call the 'inner kernel theorem'. This is the characterization of those linear operators that have kernels in $\mathbf{S}_{0}(G_{1} \times G_{2})$. Such operators are regularizing -- in the sense that they map $\mathbf{S}'_{0}(G_{1})$ into $\mathbf{S}_{0}(G_{2})$ in a $w^{*}$ to norm continuous manner. A detailed functional analytic treatment of these operators is given and applied to the case of general LCA groups. This is done without the use of Wilson bases, which have previously been employed for the case of elementary LCA groups. We apply our approach to describe natural laws of composition for operators that imitate those of linear mappings via matrix multiplications. Furthermore, we detail how these operators approximate general operators (in a weak form). As a concrete example, we derive the widespread statement of engineers and physicists that pure frequencies 'integrate' to a Dirac delta distribution in a mathematically justifiable way. 000476292 536__ $$0G:(DE-HGF)POF4-623$$a623 - Data Management and Analysis (POF4-623)$$cPOF4-623$$fPOF IV$$x0 000476292 588__ $$aDataset connected to DataCite 000476292 693__ $$0EXP:(DE-MLZ)NOSPEC-20140101$$5EXP:(DE-MLZ)NOSPEC-20140101$$eNo specific instrument$$x0 000476292 7001_ $$0P:(DE-H253)PIP1098744$$aJakobsen, Mads Bregenholt$$b1$$eCorresponding author 000476292 773__ $$0PERI:(DE-600)1462913-6$$a10.1007/s00605-022-01702-4$$p675 - 715$$tMonatshefte für Mathematik$$v198$$x0026-9255$$y2022 000476292 7870_ $$0PUBDB-2023-00297$$aJakobsen, Mads Bregenholt et.al.$$d2022$$iIsParent$$rarXiv:1806.06307$$tThe inner kernel theorem for a certain Segal algebra 000476292 8564_ $$uhttps://bib-pubdb1.desy.de/record/476292/files/HTML-Approval_of_scientific_publication.html 000476292 8564_ $$uhttps://bib-pubdb1.desy.de/record/476292/files/PDF-Approval_of_scientific_publication.pdf 000476292 8564_ $$uhttps://bib-pubdb1.desy.de/record/476292/files/Scan%2009.05.2022%2C%2010-00.pdf 000476292 8564_ $$uhttps://bib-pubdb1.desy.de/record/476292/files/Scan%2009.05.2022%2C%2010-00.pdf?subformat=pdfa$$xpdfa 000476292 8564_ $$uhttps://bib-pubdb1.desy.de/record/476292/files/document5.pdf$$yOpenAccess 000476292 8564_ $$uhttps://bib-pubdb1.desy.de/record/476292/files/s00605-022-01702-4.pdf$$yOpenAccess 000476292 8564_ $$uhttps://bib-pubdb1.desy.de/record/476292/files/document5.pdf?subformat=pdfa$$xpdfa$$yOpenAccess 000476292 8564_ $$uhttps://bib-pubdb1.desy.de/record/476292/files/s00605-022-01702-4.pdf?subformat=pdfa$$xpdfa$$yOpenAccess 000476292 8767_ $$92022-05-09$$aTODO$$d2022-05-09$$eHybrid-OA$$jDEAL$$lSpringerNature 000476292 8767_ $$92022-05-09$$aTODO$$d2022-05-09$$eOther$$jDEAL$$lSpringerNature$$zMPDL-Gebühr 000476292 909CO $$ooai:bib-pubdb1.desy.de:476292$$pdnbdelivery$$popenCost$$pVDB$$pdriver$$pOpenAPC_DEAL$$popen_access$$popenaire 000476292 9101_ $$0I:(DE-588b)2008985-5$$6P:(DE-H253)PIP1098744$$aDeutsches Elektronen-Synchrotron$$b1$$kDESY 000476292 9131_ $$0G:(DE-HGF)POF4-623$$1G:(DE-HGF)POF4-620$$2G:(DE-HGF)POF4-600$$3G:(DE-HGF)POF4$$4G:(DE-HGF)POF$$aDE-HGF$$bForschungsbereich Materie$$lMatter and Technologies$$vData Management and Analysis$$x0 000476292 9141_ $$y2022 000476292 915__ $$0StatID:(DE-HGF)0200$$2StatID$$aDBCoverage$$bSCOPUS$$d2021-01-27 000476292 915__ $$0StatID:(DE-HGF)0300$$2StatID$$aDBCoverage$$bMedline$$d2021-01-27 000476292 915__ $$0LIC:(DE-HGF)CCBY4$$2HGFVOC$$aCreative Commons Attribution CC BY 4.0 000476292 915__ $$0StatID:(DE-HGF)1150$$2StatID$$aDBCoverage$$bCurrent Contents - Physical, Chemical and Earth Sciences$$d2021-01-27 000476292 915__ $$0StatID:(DE-HGF)0113$$2StatID$$aWoS$$bScience Citation Index Expanded$$d2021-01-27 000476292 915__ $$0StatID:(DE-HGF)0150$$2StatID$$aDBCoverage$$bWeb of Science Core Collection$$d2021-01-27 000476292 915__ $$0StatID:(DE-HGF)9900$$2StatID$$aIF < 5$$d2021-01-27 000476292 915__ $$0StatID:(DE-HGF)0510$$2StatID$$aOpenAccess 000476292 915__ $$0StatID:(DE-HGF)0100$$2StatID$$aJCR$$bMONATSH MATH : 2019$$d2021-01-27 000476292 915__ $$0StatID:(DE-HGF)0160$$2StatID$$aDBCoverage$$bEssential Science Indicators$$d2021-01-27 000476292 915__ $$0StatID:(DE-HGF)0199$$2StatID$$aDBCoverage$$bClarivate Analytics Master Journal List$$d2021-01-27 000476292 915pc $$0PC:(DE-HGF)0000$$2APC$$aAPC keys set 000476292 915pc $$0PC:(DE-HGF)0001$$2APC$$aLocal Funding 000476292 915pc $$0PC:(DE-HGF)0002$$2APC$$aDFG OA Publikationskosten 000476292 915pc $$0PC:(DE-HGF)0113$$2APC$$aDEAL: Springer Nature 2020 000476292 9201_ $$0I:(DE-H253)FS-SC-20210408$$kFS-SC$$lScientific computing$$x0 000476292 9201_ $$0I:(DE-H253)U_HH-20120814$$kU HH$$lUni Hamburg$$x1 000476292 980__ $$ajournal 000476292 980__ $$aVDB 000476292 980__ $$aUNRESTRICTED 000476292 980__ $$aI:(DE-H253)FS-SC-20210408 000476292 980__ $$aI:(DE-H253)U_HH-20120814 000476292 980__ $$aAPC 000476292 9801_ $$aAPC 000476292 9801_ $$aFullTexts