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We compute the group homology, the topological K-theory of the reduced C^*-algebra, the algebraic K-theory and the algebraic L-theory of the group ring of the semi-direct product of the three-dimensional discrete Heisenberg group by Z/4.…

K-Theory and Homology · Mathematics 2014-11-11 Wolfgang Lueck

In this paper we construct new Beauville surfaces with group either $\PSL(2,p^e)$, or belonging to some other families of finite simple groups of Lie type of low Lie rank, or an alternating group, or a symmetric group, proving a conjecture…

Group Theory · Mathematics 2012-11-30 Shelly Garion , Matteo Penegini

We document some versions, in real K-theory, of well-known properties of the coarse assembly map in complex K-theory. These results are well-known, but difficult to find in the literature.

K-Theory and Homology · Mathematics 2013-08-13 John Roe

We study the Fibered Isomorphism conjecture of Farrell and Jones for groups acting on trees. We show that under certain conditions the conjecture is true for groups acting on trees when the stabilizers satisfy the conjecture. These…

K-Theory and Homology · Mathematics 2013-08-16 S. K. Roushon

We give a decomposition of the equivariant Kasparov category for discrete quantum group with torsions. As an outcome, we show that the crossed product by a discrete quantum group in a certain class preserves the UCT. We then show that…

Operator Algebras · Mathematics 2021-03-22 Yuki Arano , Adam Skalski

The Isomorphism Conjectures are translated into the language of homotopical algebra, where they resemble Thomason's descent theorems.

K-Theory and Homology · Mathematics 2007-05-23 Paul Balmer , Michel Matthey

We study a group which is hyperbolic relative to a finite family of infinite subgroups. We show that the group satisfies the coarse Baum-Connes conjecture if each subgroup belonging to the family satisfies the coarse Baum-Connes conjecture…

K-Theory and Homology · Mathematics 2014-10-09 Tomohiro Fukaya , Shin-ichi Oguni

Let $K$ be a number field with ring of integers $\mathcal{O}_K$. We describe and classify finite, flat, and linearly reductive subgroup schemes of $\mathrm{SL}_2$ over $\mathrm{Spec}\:\mathcal{O}_K$. We also establish finiteness results for…

Algebraic Geometry · Mathematics 2025-06-27 Christian Liedtke , Matthew Satriano

We give a new proof of the Mordell-Lang conjecture in positive characteristic for finitely generated subgroups. We also make some progress towards the full Mordell-Lang conjecture in positive characteristic.

Number Theory · Mathematics 2013-12-02 Paul Ziegler

It is shown that a closed solvable subgroup of a connected Lie group is compactly generated. In particular, every discrete solvable subgroup of a connected Lie group is finitely generated. Generalizations to locally compact groups are…

Group Theory · Mathematics 2011-02-19 Karl Heinrich Hofmann , Karl-Hermann Neeb

We use homological ideals in triangulated categories to get a sufficient criterion for a pair of subcategories in a triangulated category to be complementary. We apply this criterion to construct the Baum-Connes assembly map for locally…

K-Theory and Homology · Mathematics 2015-10-23 Ralf Meyer

We show how to efficiently count and generate uniformly at random finitely generated subgroups of the modular group $\textsf{PSL}(2,\mathbb{Z})$ of a given isomorphism type. The method to achieve these results relies on a natural map of…

Group Theory · Mathematics 2024-12-10 Frédérique Bassino , Cyril Nicaud , Pascal Weil

We develop a finite KKG-theory of C*-algebras following Arlettaz- H.Inassaridze's approach to finite algebraic K-theory. The Browder- Karoubi-Lambre's theorem on the orders of the elements for finite algebraic K-theory is extended to finite…

K-Theory and Homology · Mathematics 2009-10-01 Hvedri Inassaridze , Tamaz Kandelaki

We show that for non-conjugate subgroups $G_1$ and $G_2$ of a finite group $G$ there exists an extension of $G$ (by a finite group) in which the pre-images of $G_1$ and $G_2$ are not isomorphic. This allows us to show that $\mathbb Z$-coset…

Group Theory · Mathematics 2026-05-06 Ido Karshon , Alexander Lubotzky , D. B. McReynolds , Alan W. Reid , Mark Shusterman

It is proved that the assembly map in algebraic K- and L-theory with respect to the family of finite subgroups is injective for groups $\Gamma$ with finite quotient finite decomposition complexity (a strengthening of finite decomposition…

K-Theory and Homology · Mathematics 2015-07-28 Daniel Kasprowski

We develop a method for proving the Boone--Higman Conjecture for groups acting on locally finite trees. As a consequence, we prove the Boone--Higman Conjecture for all Baumslag--Solitar groups and for all free(finite rank)-by-cyclic groups,…

Group Theory · Mathematics 2025-01-27 Kai-Uwe Bux , Claudio Llosa Isenrich , Xiaolei Wu

We show how to count and randomly generate finitely generated subgroups of the modular group $\textsf{PSL}(2,\mathbb{Z})$ of a given isomorphism type. We also prove that almost malnormality and non-parabolicity are negligible properties for…

Group Theory · Mathematics 2021-03-01 Frédérique Bassino , Cyril Nicaud , Pascal Weil

We show that the image of Connes-Karoubi-Chern character, restricted to the image of the Baum-Connes assembly map in the Bott-periodized topological K-theory of the complex group algebra, lies in the elliptic summand of the (periodic)…

K-Theory and Homology · Mathematics 2007-07-26 C. Ogle

In a recent paper we claimed that both the group algebra of a finite Coxeter group $W$ as well as the Orlik-Solomon algebra of $W$ can be decomposed into a sum of induced one-dimensional representations of centralizers, one for each…

Representation Theory · Mathematics 2011-06-14 J. Matthew Douglass , Goetz Pfeiffer , Gerhard Roehrle

The aim of this article is to obtain variations on the classical theorems of Schur and Baer on finiteness of commutator subgroups, valid in the contexts of Lie algebras and Leibniz algebras over a field. Using non-abelian tensor products…

Rings and Algebras · Mathematics 2023-12-12 Guram Donadze , Tim Van der Linden