UNL Groups-Semigroups-Topology Seminar

The GST seminar this semester is held at 4:00-5:00 pm on Tuesdays in Avery 351.

Spring 2008:

Focus (half) semester on relatively hyperbolic groups
5/8/08 Robb Todd, U. Nebraska - Omaha, The figure-8 knot group is hyperbolic relative to its cusp subgroup
4/15/08, 4/22/08 Bob Ruyle, UNL, Continuation of Osin's paper on relatively hyperbolic groups, I-II
4/8/08 Sarah Rees, U. Newcastle, UK, More and less than Dehn
4/4/08 Jen Taback, Bowdoin College, Computing word length in alternate presentations of Thompson's group F
4/3/08 Jen Taback, Bowdoin College, Twisted conjugacy and quasi-isometry invariance for generalized solvable Baumslag-Solitar groups
3/28/08 Ben Fine, Fairfield U./CAISS-CUNY, On surface groups: Motivating examples in combinatorial group theory
3/24/08 Robb Todd, U. Nebraska - Omaha, Relatively hyperbolic groups: Isoperimetric functions
3/11/08 Collin Bleak, UNL, More on Relatively Hyperbolic Groups: Splitting Theorem for relatively finitely presented groups
3/4/08 Robb Todd, U. Nebraska - Omaha, More On Relatively Hyperbolic Groups: Osin Definition, Some Properties, and Some Examples
2/26/08 David McCune, UNL, Relative presentations and van Kampen diagrams
2/12/08, 2/19/08 Susan Hermiller, UNL, Introduction to weakly relatively hyperbolic groups, I-II
1/29/08 David McCune, UNL, Small cancellation groups are word hyperbolic
1/22/08 Collin Bleak, UNL, The Simultaneous Conjugacy Problem
1/15/08 Collin Bleak, UNL, Structure theorems for groups of circle homeomorphisms


Previous Semesters:

Fall 2007:

11/30/07, 12/7/07 Scott Dyer, UNL, Presenting categories of embedded cobordisms: Braids, tangles, braided and pivotal categories, and invariants, I-II
11/9/07, 11/16/07 Scott Dyer, UNL, Honest category basics for everyone, via Cartouche categories, I-II
10/19/07, 10/26/07, 11/2/07 Collin Bleak, UNL, An algebraic classification of the solvable subgroups of PL0(I), I-III
9/28/07, 10/5/07 Collin Bleak, UNL, A geometric structure theory for the solvable subgroups of PL0(I), I-II
9/14/07, 9/21/07 Robb Todd, U. Nebraska - Omaha, An introduction to Khovanov homology, I-II
8/31/07, 9/7/07 Mark Brittenham, UNL, Knots, surfaces, and Whitehead doubling, I-II

Spring 2007:

2/20/07, 3/27/07, 4/24/07 Mark Brittenham, UNL, Hyperbolic manifolds: The basics, I-III
1/30/07, 2/6/07 Scott Dyer, UNL, Hyperbolic geometry for the complete klutz, I-II
1/16/07 Organizational Meeting

Fall 2006:

Focus semester on braid, Artin, and Garside groups
11/28/06 Aditi Kar, UNL, K(G,1)'s for affine Artin groups
11/14/06, 11/21/06 Mark Brittenham, UNL, K(G,1) spaces for Artin groups, after Charney and Davis (sort of), I-II
10/31/06, 11/7/06 Scott Dyer, UNL, Braid pictures for Artin groups, I-II
10/3/06, 10/10/06 Susan Hermiller, UNL, Geodesics in Garside groups, I-II
9/26/06 John Meakin, UNL, Groupes de Garside a la Dehornoy
9/12/06, 9/19/06 Jamie Radcliffe, UNL, Garside groups: normal forms and more, I-II
8/29/06, 9/5/06 David Milan, UNL, Normal forms for braid groups, I-II
8/22/06 Organizational Meeting

Spring/Summer 2006:

8/4/06 Pascal Weil, U. Bordeaux, France, On the complexity of the Whitehead minimization problem
3/21/06 Nikolay Nikolov, U. Oxford, Great Britain, Counting groups, primes and manifolds
3/7/06 Susan Hermiller, UNL, Tame combings and almost convexities
2/21/06, 2/28/06 Susan Hermiller, UNL, Minimal almost convexity is generating set dependent, I-II
1/24/06, 1/31/06 Mark Brittenham, UNL, Morton's amazing almost equality, I-II
1/17/06 Aditi Kar, UNL, The Equivalence of Some Residual Properties of Hyperbolic Groups, II

Fall 2005:

11/29/05 Nikolay Nikolov, U. Oxford, Great Britain, Subgroups of finite index in profinite groups
11/15/05 Aditi Kar, UNL, Residual Properties of Hyperbolic Groups, I
10/25/05, 11/1/05, 11/8/05 David Milan, UNL, The C*-algebras of some inverse semigroups, I-III
9/27/05, 10/5/05 Justin James, UNL, Deciding Membership in Finitely Generated Submonoids of the Free Product of two Groups, I-II
9/13/05, 9/20/05 John Meakin, UNL, From submonoids of groups to inverse monoids, I-II (II: Toeplitz inverse monoids)
9/6/05 Justin James, UNL, An Algorithm to Decide Membership in Finitely Generated Submonoids of Free Abelian Groups

Spring 2005:

5/25/05 Zoran Sunik, Texas A&M, Thompson's group F and the weak Bruhat order
4/19/05 Susan Hermiller, UNL, Artin groups, 3-manifolds, and rewriting systems
3/29/05 Bob Ruyle, UNL, Bass-Serre theory and foldings
3/22/05 Stuart Margolis, Bar-Ilan U., Hunter College and Queens College, Inverse monoids, logic and the computational complexity of root subgroups in free groups
2/1/05, 2/8/05, 3/15/05 Bob Ruyle, UNL, Foldings in graphs of groups and the membership problem for subgroups of graphs of groups, I-III
1/18/05, 1/25/05 Justin James, UNL, The power problem and the double power problem in word hyperbolic groups

Fall 2004:

12/7/04 Patrick Bahls, U. Illinois Urbana-Champaign, Orderability in groups and monoids: truths and consequences
11/23/04, 11/30/04 Susan Hermiller, UNL, Geodesics, star-free languages, and small cancellation groups, I-II
11/16/04 Aditi Kar, UNL, Finite subgroups of hyperbolic groups
11/2/04, 11/9/04 John Meakin, UNL, Idempotent generated semigroups, I-II
10/12/04, 10/26/04 Bob Ruyle, UNL, The Hanna Neumann Conjecture for free groups and a Matching Problem for finite groups, I-II
9/22/04 Sarah Rees, U. Newcastle, UK, Groups whose co-word problem is context-free
9/14/04, 9/21/04 Jamie Radcliffe, UNL, An old application of topology to Ramsey theory, I-II
8/31/04, 9/7/04 Mark Brittenham, UNL, Canonical decompositions of 3-manifolds (and their fundamental groups), I-II

Spring/Summer 2004:

6/8/04, 6/9/04, 6/10/04 Lucas Sabalka, U. Illinois Urbana-Champaign, Braid Groups on Graphs, I-III
6/8/04 Mark Brittenham, UNL, Background on Morse theory
5/11/04 Alexei Myasnikov, City College/CUNY, Different faces of fully residually free groups and algorithmic problems
4/27/04 Zoran Sunik, Texas A&M, Hausdorff dimension of groups acting on trees
4/20/04 Chris Bourke, UNL Dept. of Computer Science and Engineering, Finite-state dimension of individual sequences
4/13/04 Susan Hermiller, UNL, Polyfree constructions for Artin groups
3/30/04, 4/6/04 Justin James, UNL, Syntactic Groups of Finitely Generated Submonoids, I-II
3/23/04 David Milan, UNL, Topologically Unrealizable Automorphisms
2/17/03, 2/24/04, 3/9/04 Enric Ventura, UNL/Universitat Politecnica de Catalunya, Barcelona, Spain, Fixed subgroups in free groups, I-III
2/6/04 Louis Zulli, Lafayette College, An extension of the Jones polynomial of classical knots
1/27/04 Susan Hermiller, UNL, Thompson's group at 40 years
1/20/03 Enric Ventura, UNL/Universitat Politecnica de Catalunya, Barcelona, Spain, A uniform version for non-amenability

Fall 2003:

11/25/03 Jamie Radcliffe, UNL, Midterm problems for the human race
11/18/03 Josh Brown-Kramer, UNL, The falsification by fellow traveler property
10/28/03, 11/4/03, 11/11/03 Mark Brittenham, UNL, Train tracks for free groups, I-III
9/30/03, 10/7/03, 10/14/03 Justin James, UNL, Coxeter groups, I-III
9/9/03, 9/16/03, 9/23/03 Pascal Weil, UNL/U. Bordeaux, France, Logic and automata, I-III
9/2/03 Enric Ventura, Universitat Politecnica de Catalunya, Barcelona, Spain, Modern consequences of the classical theorem of Takahasi

Spring 2003:

Focus semester on "From fractal groups to fractal sets" by Bartholdi, Grigorchuk, and Nekrashevych
4/29/03 Zoran Sunik, UNL, Self-similarity and and hyperbolic spaces
4/15/03, 4/22/03 Zoran Sunik, UNL, Schreier graphs and self-similar actions, I-II
4/7/03 John Meier, Lafayette College, Garside groups
4/1/03 Jamie Radcliffe, UNL, Virtual endomorphisms
3/11/03, 3/25/03 Mark Brittenham, UNL, Iterated Monodromy Groups, I-II
3/7/03 Rostislav Grigorchuk, Texas A&M, A friendly competitor to the Thompson group
2/25/03, 3/4/03 Steve Lindblad, UNL, Actions on rooted trees, I-II
2/11/03 Jamie Radcliffe, UNL, Groups and inverse semigroups associated with Penrose tilings
2/4/03 John Meakin, UNL, Self similar actions of inverse semigroups
1/21/03, 1/28/03 John Meakin, UNL, Self similar actions of groups and semigroups, I-II

Fall 2002:

12/10/02 Justin James, UNL, Closure properties of quasiconvex subsets of word hyperbolic groups
11/26/02 Bob Ruyle, UNL, Calculating the Schutzenberger Graphs of a Transition Monoid
11/12/02 Mark Brittenham, UNL, Branched surfaces, tilings, and the carrying problem
11/5/02 Steve Lindblad, UNL, Sparse Words and Schutzenberger Complexes
10/29/02 Vinod Variyam, UNL Dept. of Computer Science and Engineering, Complexity of Group-theoretic Problems
10/15/02 Susan Hermiller, UNL, Minimal almost convexity
10/8/02 Bob Ruyle, UNL, Malcev correspondence between rings and nilpotent groups
9/17/02 Steve Haataja, UNL, Inverse semigroups associated with Wiener-Hopf algebras
9/10/02 John Meakin, UNL, Inverse monoids associated with submonoids of groups
8/27/02, 9/3/02 Zoran Sunik, UNL, Test maps to metabelian groups, I-II

Spring 2002:

4/23/02 Mark Brittenham, UNL, Are "most" knots really the boundary of only one surface? Some (bad) empirical evidence
4/16/02 John Snow, Concordia U., Constructing Congruence Lattices of Finite Algebras
4/9/02 Lucas Sabalka, UNL, Geodesic growth in the braid group on three strands
4/2/02 Justin James, UNL, A solution to the cyclic submonoid membership problem for a class of Coxeter groups
3/26/02 Zoran Sunik, UNL, Baumslag-Solitar groups as dual finite automata
2/19/02, 3/5/02, 3/12/02 Mark Brittenham, UNL, 3-manifolds with finite fundamental group, I-III
2/12/02 Zoran Sunik, UNL, Periodic points of tree endomorphims, the Catalan family tree and Young tableaux
2/5/02 Mark Sapir, Vanderbilt U., Higman Embeddings
1/29/02 John Snow, Concordia U., Algebras, Relations, Compatibility, and Majority
1/22/02 John Meakin, UNL, Equations in free inverse monoids II: the extendibility problem
1/15/02 John Meakin, UNL, Equations in free inverse monoids

Fall 2001:

10/26/01 Jean-Camille Birget, Rutgers U. Camden, Filling functions on groups
10/16/01, 10/30/01, 11/6/01 Justin James, UNL, Coxeter groups and the generalized word problem, I-III
10/2/01, 10/9/01 Steve Lindblad, UNL, Knuth-Bendix for groups with infinitely many rules, I-II
9/18/01 Zoran Sunik, UNL, Groups of tree automorphisms: Introduction to branch groups
9/11/01 Zoran Sunik, UNL, Groups of tree automorphisms: Algorithmic aspects
9/4/01 Zoran Sunik, UNL, Groups of tree automorphisms: Word and torsion growth

Spring 2001:

4/10/01, 4/24/01 Justin James, UNL, The Quasiconvexity Reduction Hypothesis and its Applications, I-II
3/27/01, 4/3/01 Susan Hermiller, UNL, Homology for groups and monoids, I-II
3/20/01 Andrei Kelarev, UNL/U. Tasmania, Cayley graphs of groups and semigroups
3/2/01 Murray Elder, Texas A&M, Patterns Theory and Automatic groups
2/20/01, 2/27/01 Steve Haataja and Justin James, UNL, The perimeter of 2-complexes in coherent groups, I-II
2/6/01, 2/13/01 Bob Ruyle, UNL, Finite inverse monoids and first order theory of free groups, I-II
1/30/01 Andrei Kelarev, UNL/U. Tasmania, Combinatorial properties of groups and semigroups
1/16/01, 1/23/01 Lisa Orlandi-Korner, UNL, Outer Space, I-II

Fall 2000:

11/28/00, 12/5/04 Steve Hataaja, UNL, Non-positively curved triangles of groups, I-II
11/21/00 Justin James, UNL, The Rips trick
11/7/00, 11/14/00 Lisa Orlandi-Korner, UNL, The *real* Bieri-Neumann-Strebel invariant
10/10/00, 10/31/00 Casey Mann, UNL/U. Arkansas, Heesch, Einstein, and Dominoes -- Open Questions in Tiling, I-II
10/3/00 Mark Brittenham, UNL, Building Seifert surfaces with depth > 1 - and why BNS invariants help
9/26/00 Mark Brittenham, UNL, BNS invariants for 1-relator groups - and why a knot theorist would care
9/12/00, 9/19/00 Susan Hermiller, UNL, Coxeter groups and their geodesics, I-II
8/29/00 Alessandra Cherubini, Politecnico di Milano, Italy, Families of languages contained or containing context-free languages
8/22/00, 9/5/00 John Meakin, UNL, Geodesics in Surface Groups, I-II

Summer 2000:

8/9/00 Jean-Camille Birget, Rutgers U. Camden
7/31/00 Pascal Weil, U. Bordeaux, France
7/26/00 Susan Hermiller, UNL, N3
7/24/00 Jillian Mcleod, UNL
7/12/00, 7/17/00, 7/19/00 Stuart Margolis, Bar-Ilan U., Israel

Spring 2000:

Focus semester on tilings and tiling groups
4/10/00 Mark Brittenham, UNL, Actions by isometries, tilings, laminations, and the kitchen sink
4/3/00 Susan Hermiller, UNL, Conway's tiling groups
3/20/00, 3/27/00 John Meakin, UNL, The inverse semigroup of a tiling of Rn
3/6/00 Mark Brittenham, UNL, Translations, rotations, and the magic numbers 2,3,4, and 6
2/7/00 Lisa Orlandi-Korner, UNL, Aperiodic Tilings of the Plane
1/31/00 Lois Goss, UNL, An introduction to the Penrose tilings of the plane

Fall 1999:

11/30/99 John Meakin, UNL, Subgroups of free groups: a theorem of Marshall Hall
11/9/99, 11/16/99 Jamie Radcliffe, UNL, Asphericity for groups, I-II
11/2/99 Mark Brittenham, UNL, There is no algorithm to decide if a group is the fundamental group of a 3-manifold (after Stallings)
10/26/99 John Meakin, UNL, Asphericity and the Freiheitssatz for some finitely presented groups
10/5/99, 10/12/99 John Meakin, UNL, One-relator groups and one-relator monoids, I-II
9/7/99 Sarah Rees, U. Newcastle, Solving the word problem in real time
8/31/99, 9/14/99, 9/21/99, 9/28/99 Susan Hermiller, UNL, Tame combings for groups, I-IV

Spring 1999:

4/23/99 Jon McCammond, Texas A&M, The combinatorial Gauss-Bonnet theorem and the notion of curvature in group theory
4/14/99, 4/28/99 Bob Ruyle, Nebraska Wesleyan U., The Kervaire Conjecture and accidental group theory, I-II
3/24/99, 3/31/99, 4/7/99 Jamie Radcliffe, UNL, Bieri-Neumann-Strebel invariants for one-relator groups, I-III
3/10/99 Lisa Orlandi-Korner, UNL, The Bieri-Neumann-Strebel invariant
2/17/99 Susan Hermiller, UNL, Some geometric topology for group theorists
2/10/99 Mark Brittenham, UNL, Seifert Groups Acting on the Real Line
1/20/99, 1/27/99, 2/3/99 Mark Brittenham, UNL, Characterizing some groups which act on the real line, I-III

Page maintained by S. Hermiller.