Unitary groups of nondegenerate Hermitian forms and the homotopy groups of pseudospheres |
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Authors: | Douglas Farenick |
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Institution: | Department of Mathematics and Statistics, University of Regina, Regina, Saskatchewan S4S 0A2, Canada |
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Abstract: | The Witt Extension Theorem states that the unitary group of a finite-dimensional vector space V equipped with a nondegenerate hermitian form acts transitively on the pseudosphere induced by the form. We provide a new, constructive proof of this result for finite-dimensional vector spaces V over R, C, or H. This constructive proof is then used to prove a similar result for the unitary group of a finitely generated free right module over an abelian AW∗-algebra. The topology of these unitary groups is examined and as an application we determine the homotopy groups π1 and π2 of the induced real, complex, and quaternionic pseudospheres. |
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Keywords: | 15A33 55Q52 |
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