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On Valuations, Places and Graded Rings Associated to ∗-Orderings

Published online by Cambridge University Press:  20 November 2018

Igor Klep*
Affiliation:
Institute for Mathematics, Physics and Mechanics, Department of Mathematics, University of Ljubljana, Jadranska 19, SI-1111 Ljubljana, Slovenia e-mail: igor.klep@fmf.uni-lj.si
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Abstract

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We study natural $*$-valuations, $*$-places and graded $*$-rings associated with $*$-ordered rings. We prove that the natural $*$-valuation is always quasi-Ore and is even quasi-commutative (i.e., the corresponding graded $*$-ring is commutative), provided the ring contains an imaginary unit. Furthermore, it is proved that the graded $*$-ring is isomorphic to a twisted semigroup algebra. Our results are applied to answer a question of Cimprič regarding $*$-orderability of quantum groups.

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 2007

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