Abstract
Let k be an algebraically closed base field of characteristic zero. The category equivalence between central simple algebras and irreducible, generically free PGL n -varieties is extended to the context of central simple algebras with involution. The associated variety of a central simple algebra with involution comes with an action of \({{\rm PGL}_n\rtimes\langle\tau\rangle}\), where τ is the automorphism of PGL n given by τ (h) = (h −1)transpose. Basic properties of an involution are described in terms of the action of \({{\rm PGL}_n\rtimes\langle\tau\rangle}\) on the associated variety, and in particular in terms of the stabilizer in general position for this action.
Similar content being viewed by others
References
Blyth T.S.: Categories. Longman, London, New York (1986)
Cohn, P.M.: Algebra, 2nd edn, vol. 1. Wiley, Chichester (1982)
Knus M.-A., Merkurjev A., Rost M., Tignol J.-P.: The Book of Involutions. Am. Math. Soc., Providence (1998)
Kordonskii, V.E.: On the birational classification of algebraic group actions. Izv. Ross. Akad. Nauk Ser. Mat. 65, 61–76 (2001) [English translation in Izv. Math. 65, 57–70 (2001)]
Popov, V.L.: Sections in invariant theory. The Sophus Lie Memorial Conference (Oslo, 1992), pp. 315–361. Scand. Univ. Press, Olso (1994)
Popov, V.L., Vinberg, E.B.: Invariant theory. Algebraic Geometry IV, Encyclopedia of Mathematical Sciences, vol. 55, pp. 123–284. Springer, Heidelberg (1994)
Procesi C.: Non-commutative affine rings. Atti Accad. Naz. Lincei Mem. Cl. Sci. Fis. Mat. Natur. Sez. I 8, 239–255 (1967)
Reichstein Z.: On automorphisms of matrix invariants induced from the trace ring. Linear Algebra Appl. 193, 51–74 (1993)
Reichstein Z.: On the notion of essential dimension for algebraic groups. Transform. Groups 5(3), 265–304 (2000)
Reichstein Z., Vonessen N.: Stable affine models for algebraic group actions. J. Lie Theory 14, 563–568 (2004)
Reichstein Z., Vonessen N.: Polynomial identity rings as rings of functions. J. Algebra 310, 624–647 (2007)
Reichstein Z., Vonessen N.: Group actions on central simple algebras: a geometric approach. J. Algebra 304, 1160–1192 (2006)
Richardson R.W. Jr: Deformations of Lie subgroups and the variation of isotropy subgroups. Acta Math. 129, 35–73 (1972)
Rowen L.: Ring Theory, vol. I. Academic Press, San Diego (1988)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Vonessen, N. Central simple algebras with involution: a geometric approach. manuscripta math. 128, 453–467 (2009). https://doi.org/10.1007/s00229-008-0242-3
Received:
Revised:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00229-008-0242-3