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Deligne–Lusztig characters for finite reductive monoids
Published online by Cambridge University Press: 01 November 1997
Abstract
The theory of reductive monoids has been well developed by Renner and the author, cf. [8, 13]. This paper concerns the finite reductive monoids MF where M is a reductive monoid and F[ratio ]M→M is a Frobenius map. We show that the Deligne–Lusztig characters RT, θ of finite reductive groups GF have natural extensions to MF. We accomplish this by first showing that the action of a finite monoid (by partial transformations) on an algebraic variety gives rise to a virtual character of the monoid via étale cohomology. We then find the correct analogue of the algebraic set L−1(U) (where L is the Lang map) for M. The action of MF on this algebraic variety gives rise to virtual characters RT¯, θ where T is an F-stable maximal torus of G, T¯ the Zariski closure of T in M and θ an irreducible character of the finite commutative monoid T¯F. We go on to show that any irreducible character of MF is a component of some RT¯, θ.
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- Research Article
- Information
- Mathematical Proceedings of the Cambridge Philosophical Society , Volume 122 , Issue 3 , November 1997 , pp. 439 - 446
- Copyright
- Cambridge Philosophical Society 1997
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