Submission: 2006, Apr 18
In this article, quadratic forms over a field of characteristic different from two are generalised to so-called virtual forms over an arbitrary field. These objects turn out to be useful for the study of the Milnor K-theory of a field. The relation between both areas is established by a sequence of maps corresponding to Delzant's Stiefel-Whitney classes.
2000 Mathematics Subject Classification: 19D45, 11E04, 11E81
Keywords and Phrases: Milnor K-theory, quadratic forms, Witt-Grothendieck group, chain equivalence, Pfister forms, Stiefel-Whitney classes, isotropy
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