Publication:
Sums of squares in real rings

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http://www.ams.org/journals/tran/2004-356-07/S0002-9947-03-03438-X/S0002-9947-03-03438-X.pdf
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Publication Date
2004
Authors
Scheiderer, Claus
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American Mathematical Society
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Abstract
Let 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.
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UCM subjects
Teoría de números , Geometria algebraica
Unesco subjects
1205 Teoría de Números , 1201.01 Geometría Algebraica
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https://hdl.handle.net/20.500.14352/49910
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