Tuesday, October 20th, 15:30, CRM Small Room
Speaker: Olivier Siegenthaler (ETH Zurich)
Title: The Twisted Twin of the Grigorchuk Group
Tuesday
Seminar October 13th
Tuesday, October 13th, 15:30, CRM Small Room
Speaker: Enric Ventura (UPC)
Title: Computing fixed closures in free groups
Abstract: Let F be a finitely generated free group. We present an algorithm such that, given a subgroup H in F, decides whether H is the fixed subgroup of some family of automorphisms, or family of endomorphisms of F and, in the affirmative case, finds such a family. The algorithm combines both combinatorial and geometric methods.
Speaker: Enric Ventura (UPC)
Title: Computing fixed closures in free groups
Abstract: Let F be a finitely generated free group. We present an algorithm such that, given a subgroup H in F, decides whether H is the fixed subgroup of some family of automorphisms, or family of endomorphisms of F and, in the affirmative case, finds such a family. The algorithm combines both combinatorial and geometric methods.
Seminar September 22nd
Welcome to the Barcelona Group Theory Seminar for the year 2009-10. Official meeting time this semester is Tuesdays at 15:30.
Tuesday, September 22nd, 15:30, CRM Small Room
Speaker: Warren Dicks (UAB)
Title: On Leighton's graph covering theorem
Tuesday, September 22nd, 15:30, CRM Small Room
Speaker: Warren Dicks (UAB)
Title: On Leighton's graph covering theorem
Wednesday
Seminar June 29th
Monday, June 29th, 13:00, CRM Small Room
Speaker: Martin Kassabov, Cornell University
Title: Subspace arrangements and property T
Abstract: I will mainly talk about (my viewpoint at) a method for proving property T started by Dymara and Januszkiewicz. Their original motivation came from groups action on dimensional building, but the refined idea does not used anything more angles between subspaces in an finite dimensional Euclidean space. Parts of the talk are based on a work of M. Ershov and A. Jaikin.
Speaker: Martin Kassabov, Cornell University
Title: Subspace arrangements and property T
Abstract: I will mainly talk about (my viewpoint at) a method for proving property T started by Dymara and Januszkiewicz. Their original motivation came from groups action on dimensional building, but the refined idea does not used anything more angles between subspaces in an finite dimensional Euclidean space. Parts of the talk are based on a work of M. Ershov and A. Jaikin.
Friday
Seminar June 3rd
We will have a double session of the seminar at the same time as the Hyperbolic Groups course:
Wednesday June 3rd, Room 005, FME, Campus Sud UPC
First Talk, 11:00
Speaker: José Manuel Higes López, Universidad Complutense de Madrid
Title: The coarse classification of countable abelian groups
Abstract: We will show the classification of countable abelian groups up to coarse equivalence. As an application we will use this result to detect which groups are coarsely equivalent to countable abelian groups. Joint with T. Banakh, I. Zarichnyi.
Second talk, 12:00
Speaker: Lars Louder, University of Michigan
Title: Graphs of subgroups of free groups
Abstract: We will develop, using Stallings' folding, graphs of groups, and a process called "blowing up," a simple topological model for representing graphs of subgroups of free groups. Applications to be discussed include simple proofs of some old results of combinatorial group theory. Generalizations of the technique and of these seemingly simple ideas to limit groups are important in the dimension theory for algebraic varieties defined over the free group.
Wednesday June 3rd, Room 005, FME, Campus Sud UPC
First Talk, 11:00
Speaker: José Manuel Higes López, Universidad Complutense de Madrid
Title: The coarse classification of countable abelian groups
Abstract: We will show the classification of countable abelian groups up to coarse equivalence. As an application we will use this result to detect which groups are coarsely equivalent to countable abelian groups. Joint with T. Banakh, I. Zarichnyi.
Second talk, 12:00
Speaker: Lars Louder, University of Michigan
Title: Graphs of subgroups of free groups
Abstract: We will develop, using Stallings' folding, graphs of groups, and a process called "blowing up," a simple topological model for representing graphs of subgroups of free groups. Applications to be discussed include simple proofs of some old results of combinatorial group theory. Generalizations of the technique and of these seemingly simple ideas to limit groups are important in the dimension theory for algebraic varieties defined over the free group.
Course on Hyperbolic Groups, June 2nd to 4th
As an event for the graduate class "Seminar on Group Theory", there will be a three-day minicourse.
Tuesday June 2nd to Thursday June 4th, 15.00 to 18:00, Room 005, FME, UPC Campus Sud
Speaker: Oleg Bogopolski, Universität Düsseldorf
Title: Hyperbolic groups
Tuesday June 2nd to Thursday June 4th, 15.00 to 18:00, Room 005, FME, UPC Campus Sud
Speaker: Oleg Bogopolski, Universität Düsseldorf
Title: Hyperbolic groups
Thursday
Seminar May 25th
Monday, May 25th, 13:00, CRM Small Room
Speaker: Lluís Bacardit (UAB)
Title: A generalization of theorem of Birman and Hilden
Abstract: A Theorem of Birman and Hilden says that the standard representation of the braid group by automorphisms of a free group $F_n$ remains faithful after passing to a free product of cyclic groups $C_k^{*n}$. If we take a finite index subgroup of $C_k^{*n}$ invariant by the action of the braid group, the action also is faithful. These two facts allow us to embed braid group in mapping class group of genus greater than 0. We will give a generalization of the Birman Hilden theorem to orientable surface with one boundary component and show some inclusion of mapping class groups in mapping class groups of greater genus.
Speaker: Lluís Bacardit (UAB)
Title: A generalization of theorem of Birman and Hilden
Abstract: A Theorem of Birman and Hilden says that the standard representation of the braid group by automorphisms of a free group $F_n$ remains faithful after passing to a free product of cyclic groups $C_k^{*n}$. If we take a finite index subgroup of $C_k^{*n}$ invariant by the action of the braid group, the action also is faithful. These two facts allow us to embed braid group in mapping class group of genus greater than 0. We will give a generalization of the Birman Hilden theorem to orientable surface with one boundary component and show some inclusion of mapping class groups in mapping class groups of greater genus.
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