The low-dimensional homology of crossed modules.
The lower central series of a fiber-type arrangement.
The Mac Lane method of construction and classification of extensions of cyclic groups by their automorphism groups.
The normalizer splitting conjecture for p-compact groups
Let X be a p-compact group, with maximal torus BT → BX, maximal torus normalizer BN and Weyl group . We prove that for an odd prime p, the fibration has a section, which is unique up to vertical homotopy.
The Number of Stem Covers of an Elementary Abelian p-Group.
The Obstruction theory of Group Extensions and H^3(Q, A) in Abstract Categories
The Poincaré Series of a Coxeter Group.
The p-period of an infinite group.
For Γ a group of finite virtual cohomological dimension and a prime p, the p-period of Γ is defined to be the least positive integer d such that Farrell cohomology groups Hi(Γ; M) and Hi+d(Γ; M) have naturally isomorphic ZΓ modules M.We generalize a result of Swan on the p-period of a finite p-periodic group to a p-periodic infinite group, i.e., we prove that the p-period of a p-periodic group Γ of finite vcd is 2LCM(|N(〈x〉) / C(〈x〉)|) if the Γ has a finite quotient whose a p-Sylow subgroup is elementary...
The Roquette category of finite -groups
Let be a prime number. This paper introduces the Roquette category of finite -groups, which is an additive tensor category containing all finite -groups among its objects. In , every finite -group admits a canonical direct summand , called the edge of . Moreover splits uniquely as a direct sum of edges of Roquette -groups, and the tensor structure of can be described in terms of such edges. The main motivation for considering this category is that the additive functors from to...
The Second Homology Group of the Mapping Class Group of an Orientable Surface.
The strong amalgamation property and (effective) codescent morphisms.
The variety of an indecomposable module is connected.
The virtual cohomological dimension of the mapping class group of an orientable surface.
The Whitehead categorical group of derivations.
The...-CATEGORY OF A SEMIGROUP.
Théorie de Schreier supérieure
Thick subcategories of the stable module category
We study the thick subcategories of the stable category of finitely generated modules for the principal block of the group algebra of a finite group G over a field of characteristic p. In case G is a p-group we obtain a complete classification of the thick subcategories. The same classification works whenever the nucleus of the cohomology variety is zero. In case the nucleus is nonzero, we describe some examples which lead us to believe that there are always infinitely many thick subcategories concentrated...
Three-Dimensional Poincaré Duality Groups Which Are Extensions.
Tiling systems and homology of lattices in tree products.
Torsors and special extensions