arXiv subjects

Eddy Godelle

Publications and source records attributed to Eddy Godelle.

28 records · Page 2Linked to original sources

arXiv2009

Stable set of self map

The attracting set and the inverse limit set are important objects associated to a self-map on a set. We call \emph{stable set} of the self-map the projection of the inverse limit set. It is included in the attracting set, but is not equal in the general case. Here we determine whether or not the equality holds in several particular cases, among which are the case of a dense range continuous function on an Hilbert space, and the case of a substitution over left infinite words.

math.GR↗

arXiv2009

A note on Renner monoids

We provide every Renner monoids with a monoid presentation, and we introduce a length function which extends the Coxeter length function.

math.GR↗

arXiv2008

Parabolic subgroups of Garside groups II: ribbons

We introduce and investigate the ribbon groupoid associated with a Garside group. Under a technical hypothesis, we prove that this category is a Garside groupoid. We decompose this groupoid into a semi-direct product of two of its parabolic subgroupoids and provide a groupoid presentation. In order to established the latter result, we describe quasi-centralizers in Garside groups. All results hold in the particular case of Artin-Tits groups of spherical type.

math.GR↗

arXiv2008

The conjugacy problem in right-angled Artin groups and their subgroups

We prove that the conjugacy problem in right-angled Artin groups (RAAGs), as well as in a large and natural class of subgroups of RAAGs, can be solved in linear-time. This class of subgroups contains, for instance, all graph braid groups (i.e. fundamental groups of configuration spaces of points in graphs), many hyperbolic groups, and it coincides with the class of fundamental groups of ``special cube complexes'' studied independently by Haglund and Wise.

math.GR↗

arXiv2005

Questions on surface braid groups

We provide new group presentations for surface braid groups which are positive. We study some properties of such presentations and we solve the conjugacy problem in a particular case.

math.GR↗

arXiv2004

Parabolic subgroups of Garside groups

A Garside monoid is a cancellative monoid with a finite lattice generating set; a Garside group is the group of fractions of a Garside monoid. The family of Garside groups contains the Artin-Tits groups of spherical type. We generalise the well-known notion of a parabolic subgroup of an Artin-Tits group into that of a parabolic subgroup of a Garside group. We also define the more general notion of a Garside subgroup of a Garside group, which is related to the notion of LCM-homomorphisms between Artin-Tits groups. We prove that most of the properties of parabolic subgroups extend to this subgroups.

math.GR↗

arXiv2003

Conjugacy in Artin groups and applications to the classification of surfaces

We show thatthe double reversing algorithm proposed by dehornoy for solving the word problem in the braid group can also be used to recognize the conjugates of powers of the generators in an Artin group of spherical type. The proof uses a characterization of these powers in terms of their fractional decomposition. This algorithm could have potential applications to braid-based cryptography; it also provides a fast method for testing a necessary condition in the classification of surfaces in algebraic geometry.

math.GR↗

arXiv2003

On singular Artin monoids

In this paper we study some combinatorial aspects of the singular Artin monoids. Firstly, we show that a singular Artin monoid $SA$ can be presented as a semidirect product of a graph monoid with its associated Artin group $A$. Such a decomposition implies that a singular Artin monoid embeds in a group. Secondly, we give a solution to the word problem for the FC type singular Artin monoids. Afterwards, we show that FC type singular Artin monoids have the FRZ property. Briefly speaking, this property says that the centralizer in $SA$ of any non-zero power of a standard singular generator $τ_s$ coincides with the centralizer of any non-zero power of the corresponding non-singular generator $σ_s$. Finally, we prove Birman's conjecture, namely, that the desingularization map $η: SA \to \Z [A]$ is injective, for right-angled singular Artin monoids.

math.GR↗

arXiv2002

Morphismes injectifs entre groupes d'Artin-Tits

We construct a family of morphisms between Artin-Tits groups which generalise the ones constructed by J. Crisp in [Injective maps between Artin groups, Proceedings of the Special Year in Geometric Group Theory, Berlin, (1999), 119 -- 138]. We show that their restrictions to the positive Artin monoids respect normal forms, and that for Artin-Tits groups of type FC, these morphisms are injective. The proof of the second result uses the Deligne Complex, and the normal cube paths constructed in [G. Niblo and L. Reeves, The geometry of cube complexes and the complexity of their fundamental groups, Topology 37 (1998) 621-633] and [J.A. Altobelli and R. Charney, A geometric Rational Form for Artin Groups of FC type, Geom. Dedicata, 79 (2000) 277-289]. Resume: On construit une classe de morphismes entre groupes d'Artin-Tits qui generalise celle construite par J. Crisp dans [Injective maps between Artin groups, Proceedings of the Special Year in Geometric Group Theory, Berlin, (1999), 119 -- 138]. On montre que leurs restrictions aux monoides respectent les formes normales, et que pour les groupes d'Artin-Tits de type FC ces morphismes sont injectifs. La demonstration du second resultat utilise le complexe de Deligne et les chemins cubiques normaux construits dans [G. Niblo et L. Reeves, The geometry of cube complexes and the complexity of their fundamental groups, Topology 37 (1998) 621-633] et [J.A. Altobelli et R. Charney, A geometric Rational Form for Artin Groups of FC type, Geom. Dedicata, 79 (2000) 277-289].

math.GR↗

arXiv2002

Normalisateurs et groupes d'Artin-Tits de type sphérique

Let $(A_S,S)$ be an Artin-Tits and $X$ a subset of $S$ ; denote by $A_X$ the subgroup of $A_S$ generated by $X$. When $A_S$ is of spherical type, we prove that the normalizer and the commensurator of $A_X$ in $A_S$ are equal and are the product of $A_X$ by the quasi-centralizer of $A_X$ in $A_S$. Looking to the associated monoids $A_S^+$ and $A_X^+$, we describe the quasi-centralizer of $A_X^+$ in $A_S^+$ thanks to results in Coxeter groups. These two results generalize earlier results of Paris. Finaly, we compare, in the spherical case, the normalizer of a parabolic subgroup in the Artin-Tits group and in the Coxeter group.

math.GR↗