Browsing by Subject "Mackey functor"

Now showing 1 - 7 of 7

Open Access
Canonical induction for trivial source rings
(2013) Büyükçolak, Yasemin
We discuss the canonical induction formula for some special Mackey functors by following the construction of Boltje. These functors are the ordinary and modular character rings and the trivial source rings. Making use of a natural correspondence between the Mackey algebra and the finite algebra spanned by the three kinds of basic bisets, namely the conjugation, restriction and induction, we investigate the canonical induction formula in terms of the theory of bisets. We focus on the trivial source rings and the canonical induction formula for them. The main aim is to get an explicit formula for the canonical induction of regular bimodules in the trivial source. This gives a first step towards for the canonical induction of blocks.
Open Access
A correspondence of simple alcahestic group functors
(2008) Coşkun, Olcay
Representation theory of finite groups associates two classical constructions to a group G, namely the representation ring of G and the Burnside ring of G. These rings share a special structure that comes from three classical maps, namely restriction, conjugation, and transfer maps. These are not the only objects having this structure and the theory of Mackey functors, introduced by Green, unifies the treatment of such objects. The above constructions share a further structure that comes from two other maps, the inflation map and the deflation map. Unified treatment of the objects having this further structure was introduced by Bouc [4]. These objects are called biset functors. Between Mackey functors and biset functors there lies more natural constructions, for example the functor of group (co)homology. In order to handle these intermediate structures, Bouc introduced another concept, now known as globallydefined Mackey functors, a name given by Webb. In this thesis, we unify the above theories by considering the algebra whose module category is equivalent to the category of biset functors and by introducing alcahestic group functors. Our main results classify and describe simple alcahestic group functors and give a criterion of semisimplicity for the categories of these functors.
Open Access
Green correspondence for Mackey functors
(2008) Uç, Mehmet
The Green corespondence for modules of group algebras was introduced by Green in 1964. A version for Mackey functors was introduced by Sasaki in 1982. Sasaki’s characterization of Mackey functor correspondence was based on the theory of Green functors. In this thesis, we give Sasaki’s characterization and an alternative characterization of the Mackey functor correspondence. Our characterization is closer to Green’s original module theoretic approach. We show that the two characterizations are equivalent. This yields a new way of determining vertices, sources and Green correspondents; we shall illustrate this with some examples.
Open Access
Inductions, restrictions, evaluations, and sunfunctors of Mackey functors
(2008) Yaraneri, Ergün
Open Access
Kernels, inflations, evaluations, and imprimitivity of Mackey functors
(Elsevier, 2008-03-01) Yaraneri, E.
Let M be a Mackey functor for a finite group G. By the kernel of M we mean the largest normal subgroup N of G such that M can be inflated from a Mackey functor for G / N. We first study kernels of Mackey functors, and (relative) projectivity of inflated Mackey functors. For a normal subgroup N of G, denoting by PH, VG the projective cover of a simple Mackey functor for G of the form SH, VG we next try to answer the question: how are the Mackey functors PH / N, VG / N and PH, VG related? We then study imprimitive Mackey functors by which we mean Mackey functors for G induced from Mackey functors for proper subgroups of G. We obtain some results about imprimitive Mackey functors of the form PH, VG, including a Mackey functor version of Fong's theorem on induced modules of modular group algebras of p-solvable groups. Aiming to characterize subgroups H of G for which the module PH, VG (H) is the projective cover of the simple K over(N, -)G (H)-module V where the coefficient ring K is a field, we finally study evaluations of Mackey functors. © 2007 Elsevier Inc. All rights reserved.
Open Access
Socles and radicals of Mackey functors
(2009) Yaraneri, E.
We study the socle and the radical of a Mackey functor M for a finite group G over a field K (usually, of characteristic p > 0). For a subgroup H of G, we construct bijections between some classes of the simple subfunctors of M and some classes of the simple K over(N, -)G (H)-submodules of M (H). We relate the multiplicity of a simple Mackey functor SH, V G in the socle of M to the multiplicity of V in the socle of a certain K over(N, -)G (H)-submodule of M (H). We also obtain similar results for the maximal subfunctors of M. We then apply these general results to some special Mackey functors for G, including the functors obtained by inducing or restricting a simple Mackey functor, Mackey functors for a p-group, the fixed point functor, and the Burnside functor BK G. For instance, we find the first four top factors of the radical series of BK G for a p-group G, and assuming further that G is an abelian p-group we find the radical series of BK G. © 2009 Elsevier Inc. All rights reserved.
Open Access
A Swan length theorem and a Fong dimension theorem for Mackey algebras
(Academic Press, 2007) Yaraneri, E.
We first present some results about Mackey algebras of p-groups over fields of characteristic p, including their primitive idempotents and decompositions of their simple and principal indecomposable modules under restriction. We then apply these results together with a Green's indecomposability theorem for Mackey algebras to obtain Mackey algebra versions of some classical results of group algebras which are mostly related to restriction, induction and dimensions of modules. Our results about dimensions include Mackey algebra analogues of Dickson's theorem, Swan's theorem and Fong's dimension formula. © 2006 Elsevier Inc. All rights reserved.