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Sums of squares of linear forms: the quaternions approach

dc.contributor.authorFernando Galván, José Francisco
dc.contributor.authorRuiz Sancho, Jesús María
dc.contributor.authorScheiderer, Claus
dc.date.accessioned2023-06-20T10:35:12Z
dc.date.available2023-06-20T10:35:12Z
dc.date.issued2006
dc.description.abstractLet A = k[y] be the polynomial ring in one single variable y over a field k. We discuss the number of squares needed to represent sums of squares of linear forms with coefficients in the ring A. We use quaternions to obtain bounds when the Pythagoras number of A is ≤ 4. This provides bounds for the Pythagoras number of algebraic curves and algebroid surfaces over k.
dc.description.departmentDepto. de Álgebra, Geometría y Topología
dc.description.facultyFac. de Ciencias Matemáticas
dc.description.refereedFALSE
dc.description.statusunpub
dc.eprint.idhttps://eprints.ucm.es/id/eprint/21528
dc.identifier.officialurlhttp://www.mat.ucm.es/~jesusr/pdfs/preprints/IHP.pdf
dc.identifier.relatedurlhttp://www.mat.ucm.es
dc.identifier.urihttps://hdl.handle.net/20.500.14352/50666
dc.journal.titleUCM GT preprint
dc.language.isoeng
dc.page.final15
dc.page.initial1
dc.rights.accessRightsopen access
dc.subject.cdu512.7
dc.subject.keywordPythagoras number
dc.subject.keywordPfister bound
dc.subject.keywordquaternions
dc.subject.ucmGeometria algebraica
dc.subject.unesco1201.01 Geometría Algebraica
dc.titleSums of squares of linear forms: the quaternions approach
dc.typejournal article
dcterms.referencesE. Becker: Hereditarily-Pythagorean fields and orderings of higher level. Monografías de Matemática [Mathematical Monographs], 29. Rio de Janeiro: Instituto de Matemática Pura e Aplicada, 1978. J. Bochnak, M. Coste, M. F. Roy: Real Algebraic Geometry. Ergeb. Math. 36. Berlin Heidelberg New York: Springer-Verlag, 1998. J. W. S. Cassels: On the representation of rational functions as sums of squares. Acta Arith. 9 (1964) 79–82. M. D. Choi, Z. D. Dai, T. Y. Lam, B. Reznick: The Pythagoras number of some affine algebras and local algebras. J. reine Angew. Math. 336 (1982) 45–82. M. D. Choi, T. Y. Lam, B. Reznick: Real zeros of positive semidefinite forms. I. Math. Z. 171, 1–26 (1980). D. Z. Djoković: Hermitean matrices over polynomial rings. J. Algebra 43 (1976) 359–374. J. F. Fernando: On the Pythagoras numbers of real analytic rings. J. Algebra 356 (2004) 2663–2684. J. F. Fernando, J. M. Ruiz, C. Scheiderer: Sums of squares in real rings. Trans. AMS 243 (2001) 321–338. J. F. Fernando, J. M. Ruiz, C. Scheiderer: Sums of squares of linear forms. To appear in Math. Research Letters. T.W. Hungerford: Algebra. Graduate Text in Math. 73. Berlin Heidelberg New York: Springer Verlag, 1974. J. M. Ruiz: On pythagorean real algebroid curves. Rocky Mountain J. Math. 14 (1984) 899–901. C. Scheiderer: On sums of squares in local rings. J. reine angew. Math. 540 (2001), 205–227.
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relation.isAuthorOfPublication.latestForDiscovery499732d5-c130-4ea6-8541-c4ec934da408

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