Displaying 21 – 40 of 51

Showing per page

Metric Characterizations of Superreflexivity in Terms of Word Hyperbolic Groups and Finite Graphs

Mikhail Ostrovskii (2014)

Analysis and Geometry in Metric Spaces

We show that superreflexivity can be characterized in terms of bilipschitz embeddability of word hyperbolic groups.We compare characterizations of superrefiexivity in terms of diamond graphs and binary trees.We show that there exist sequences of series-parallel graphs of increasing topological complexitywhich admit uniformly bilipschitz embeddings into a Hilbert space, and thus do not characterize superrefiexivity.

Metric Ricci Curvature and Flow for PL Manifolds

Emil Saucan (2013)

Actes des rencontres du CIRM

We summarize here the main ideas and results of our papers [28], [14], as presented at the 2013 CIRM Meeting on Discrete curvature and we augment these by bringing up an application of one of our main results, namely to solving a problem regarding cube complexes.

Minimal length coset representatives for quotients of parabolic subgroups in Coxeter groups

Fabio Stumbo (2000)

Bollettino dell'Unione Matematica Italiana

In questo lavoro viene trovata un'espressione esplicita per i rappresentanti dei laterali di sottogrupi parabolici di gruppi di Coxeter aventi lunghezza minima: dato un sistema di Coxeter W , S ed un suo sottogruppo parabolico W I , I , con I S , si determina esplicitamente in ogni laterale W I w di W I un elemento avente lunghezza minima. Nella sezione 2 trattiamo i casi classici, i.e. W = A n , B n e D n . Dopo ciò, nella sezione 3, diamo una procedura per risolvere il problema nei restanti casi eccezionali, insieme a qualche...

Modularità nei gruppi non-periodici

Maria De Falco (2005)

Bollettino dell'Unione Matematica Italiana

In questo lavoro sono contenuti alcuni risultati riguardanti la struttura dei gruppi non-periodici in cui sottogruppi verificano opportune condizioni di modularità.

Modules over group rings of soluble groups with a certain condition of maximality

Olga Dashkova (2011)

Open Mathematics

Let A be an R G-module, where R is an integral domain and G is a soluble group. Suppose that C G(A) = 1 and A/C A(G) is not a noetherian R-module. Let L nnd(G) be the family of all subgroups H of G such that A/C A(H) is not a noetherian R-module. In this paper we study the structure of those G for which L nnd(G) satisfies the maximal condition.

Moduli spaces of local systems and higher Teichmüller theory

Vladimir Fock, Alexander Goncharov (2006)

Publications Mathématiques de l'IHÉS

Let G be a split semisimple algebraic group over Q with trivial center. Let S be a compact oriented surface, with or without boundary. We define positive representations of the fundamental group of S to G(R), construct explicitly all positive representations, and prove that they are faithful, discrete, and positive hyperbolic; the moduli space of positive representations is a topologically trivial open domain in the space of all representations. When S have holes, we defined two moduli spaces closely...

Monoid presentations of groups by finite special string-rewriting systems

Duncan W. Parkes, V. Yu. Shavrukov, Richard M. Thomas (2004)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

We show that the class of groups which have monoid presentations by means of finite special [ λ ] -confluent string-rewriting systems strictly contains the class of plain groups (the groups which are free products of a finitely generated free group and finitely many finite groups), and that any group which has an infinite cyclic central subgroup can be presented by such a string-rewriting system if and only if it is the direct product of an infinite cyclic group and a finite cyclic group.

Monoid presentations of groups by finite special string-rewriting systems

Duncan W. Parkes, V. Yu. Shavrukov, Richard M. Thomas (2010)

RAIRO - Theoretical Informatics and Applications

We show that the class of groups which have monoid presentations by means of finite special [λ]-confluent string-rewriting systems strictly contains the class of plain groups (the groups which are free products of a finitely generated free group and finitely many finite groups), and that any group which has an infinite cyclic central subgroup can be presented by such a string-rewriting system if and only if it is the direct product of an infinite cyclic group and a finite cyclic group.

Currently displaying 21 – 40 of 51