Real Algebraic and Analytic Geometry
Submission: 2003, August 19.
This is a survey about the representation of positive semidefinite elements as sums of squares from a local viewpoint, in the sense of analytic geometry. Here, we present the most recent results in the more general frame of excellent henselian local rings with real closed residue field.
Mathematics Subject Classification (2000): 14P99, 11E25, 32B10, 32S05.
Keywords and Phrases: sum of squares, positive semidefinite element, excellent henselian local rings, real closed field.
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