Fernando Galván, José FranciscoRuiz Sancho, Jesús MaríaScheiderer, Claus2023-06-202023-06-2020040002-994710.1090/S0002-9947-03-03438-Xhttps://hdl.handle.net/20.500.14352/49910Let A be an excellent ring. We show that if the real dimension of A is at least three then A has in finite Pythagoras number, and there exists a positive semidefinite element in A which is not a sum of squares in A.engjournal articlehttp://www.ams.org/journals/tran/2004-356-07/S0002-9947-03-03438-X/S0002-9947-03-03438-X.pdfhttp://www.ams.org/restricted access512.7511Positive semi-definite polynomialExcellent ringReal spectrumComplete local ringTeoría de númerosGeometria algebraica1205 Teoría de Números1201.01 Geometría Algebraica