In mathematics, a mirabolic subgroup of the general linear group GLn(k) is a subgroup consisting of automorphisms fixing a given non-zero vector in kn. Mirabolic subgroups were introduced by (Gelfand & Kajdan 1975). The image of a mirabolic subgroup in the projective general linear group is a parabolic subgroup consisting of all elements fixing a given point of projective space. The word "mirabolic" is a portmanteau of "miraculous parabolic". As an algebraic group, a mirabolic subgroup is the semidirect product of a vector space with its group of automorphisms, and such groups are called mirabolic groups. The mirabolic subgroup is used to define the Kirillov model of a representation of the general linear group.
As an example, the group of all matrices of the form where a is a nonzero element of the field k and b is any element of k is a mirabolic subgroup of the 2-dimensional general linear group.
References
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- Bushnell, Colin J.; Henniart, Guy (2006), The local Langlands conjecture for GL(2), Grundlehren der Mathematischen Wissenschaften [Fundamental Principles of Mathematical Sciences], vol. 335, Berlin, New York: Springer-Verlag, doi:10.1007/3-540-31511-X, ISBN 978-3-540-31486-8, MR 2234120
- Finkelberg, Michael; Ginzburg, Victor (2010), "On mirabolic D-modules", International Mathematics Research Notices (15): 2947–2986, doi:10.1093/imrn/rnp216, ISSN 1073-7928, MR 2673716
- Gelfand, I. M.; Kajdan, D. A. (1975) [1971], "Representations of the group GL(n,K) where K is a local field", in Gelfand, I. M. (ed.), Lie groups and their representations (Proc. Summer School, Bolyai János Math. Soc., Budapest, 1971), Halsted, New York, pp. 95–118, ISBN 978-0-470-29600-4, MR 0404534