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

Spring 2018:

2/27/18 Gabe Islambouli, U. Virginia, TBA
1/25/18 Ashley Johnson, U. North Alabama, TBA
1/9/18 Robert Huben, UNL, TBA

Fall 2017:


Focus half of a semester on self-similar groups
12/5/17 Gary DeClerk, UNL, TBA
11/28/17 Andrew Hayes, UNL, TBA
11/14/17 Corbin Groothuis, UNL, Bi-invertible automata and more
11/7/17 Jesse Moeller, UNL, Branch groups, contracting groups, and more
10/31/17 Vince Longo, UNL, Wreath products and self-similar groups
10/24/17 Aurora Marks, UNL, Introduction self-similar groups and the Grigorchuk group
10/10/17 Hannah Schwartz, Bryn Mawr C., 1 is enough
10/5/17 Ryan Blair, California State U. Long Beach, Distortion and the bridge distance of knots
10/3/17 Corbin Groothuis, UNL, Cryptography with (semi)groups
9/26/17 Susan Hermiller, UNL, Measuring the complexity of orderings on groups
9/19/17 Robert Huben, UNL, The word problem in hyperbolic groups
9/12/17 Alex Zupan, UNL, Picturing knotted surfaces in dimension four
9/7/17 Marty Scharlemann, U. California-Santa Barbara, Uniqueness in Waldhausen's theorem
9/5/17 Mark Brittenham, UNL, A counterexample to a conjecture on unknotting number (for real this time)
8/29/17 Tye Lidman, North Carolina State U., Band surgeries and lens space surgeries

Spring/Summer 2017:

7/3/17 Sarah Rees, U. Newcastle, UK, Rewriting in Artin groups
5/11/17 Yago Antolin, U. Autonoma Madrid, Spain, Dehn fillings theorem and applications
4/25/17 Jamie Radcliffe, UNL, Hilbert's third problem
4/18/17 Marla Williams, UNL, Tricoloring bridge trisections
4/11/17 Tim Susse, UNL, Outer automorphism groups of right-angled Coxeter groups
4/4/17 Maranda Franke, UNL, Languages, geodesics, and HNN extensions
3/29/17 Carolyn Otto, U. Wisconsin - Eau Claire, Every genus 1 algebraically slice knot is 1-solvable
3/28/17 Corbin Groothuis, UNL, Some fun with pseudovarieties
3/15/17 Scott Taylor, Colby College, Additive Invariants of Knots, Graphs, and 3-Manifolds
3/14/17 Katie Tucker, UNL, A finite generating set for Mod(S_g)
3/7/17 Gili Golan, Vanderbilt U., The generation problem in Thompson group F
2/28/17 Margaret Doig, Creighton U., Finite surgeries - an application of Heegaard Floer homology to a traditional knot theory question
Focus third of a semester on mapping class groups
2/21/17 Gary DeClerk, UNL, More Dehn Twists!
2/14/17 Vince Longo, UNL, Dehn twists and their properties
2/7/17 Matt Mills, UNL, The Alexander Method
1/31/17 Jesse Moeller, UNL, Mapping class groups basics
1/24/17 Aurora Marks, UNL, Surfaces, curves and hyperbolic geometry
1/17/17 (Snow day)
1/9/17 Organizational meeting



Previous Semesters:

Fall 2016:

12/6/16 Katie Tucker and Karina Uhing, UNL, Automatic groups and mapping class groups
11/29/16 Marla Williams, UNL, Heegaard splittings of 3-manifolds
11/15/16 Mark Brittenham, UNL, Three conjectures on unknotting number
11/8/16 Corbin Groothuis, UNL, Electoral semimagmas and universal algebra
11/1/16 Ken Baker, U. Miami, Asymmetric L-space knots
10/25/16 Aurora Marks, UNL, Geodesic growth of groups
10/11/16 Maranda Franke, UNL, Finite generating sets of relatively hyperbolic groups and applications to geodesic languages
10/4/16 Tim Susse, UNL, Factor systems and the geometry of CAT(0) cube complexes
9/27/16 Gary DeClerk, UNL, Ordering graph products of groups
9/20/16 Vince Longo, UNL, State invariants of two-bridge knots
9/13/16 Meggan Hass, UNL, An Introduction to topological data analysis
9/6/16 Alex Zupan, UNL, The Generalized property R conjecture
8/30/16 Organizational meeting
8/23/16 Stuart Margolis, Bar-Ilan U., CW decompositions, LeRay numbers and the global dimension of left regular band algebras

Spring/Summer 2016:

7/25/16 Nathan Corwin, Rutgers U., An introduction Thompson's group F and some normal forms
7/25/16 Melanie DeVries, MetaCommunications, Classical unknotting moves and the welded knots
4/26/16 Tye Lidman, Inst. for Advanced Study, Cosmetic crossings in knots
4/19/16 Derek Holt, U. Warwick, UK, Generalized word problems in groups and formal language theory
4/12/16 Maranda Franke, UNL, Geodesic language complexity and group structure
4/5/16 Katie Tucker, UNL, An Introduction to virtual knot theory
4/1/16 Mark Brittenham, UNL, The ups and downs of unknotting number
3/29/16 Matt Mills, UNL, Bases for cluster algebras from surfaces
3/15/16 Andy Eisenberg, Oklahoma State U., Right-angled Coxeter group recognition and decomposition
3/8/16 Aaron Calderon, UNL, Geodesic languages in groups
3/1/16 Meggan Hass, UNL, Self-Similar groups and ends of Schreier graphs
2/23/16 David McCune, William Jewell C., An introduction to self-similar groups
2/16/16 Corbin Groothuis, UNL, In the eye of the beholder
2/9/16 Jeff Meier, Indiana U., Trisections and Dehn surgery
2/2/16 Snow day!
1/19/16, 1/26/16 Nick Owad, UNL, Bridge spectra of cables to 2-bridge knots
1/12/16 Organizational meeting

Fall 2015:

12/8/15 Muhammad Inam, UNL, The word problem for a class of positively presented semigroups and inverse semigroups
12/1/15 Zoran Sunic, Texas A&M U., Deciding if a right-angled Artin group is free-by-free is NP-complete
12/1/15 Zoran Sunic, Texas A&M U., Left orders on free products and left relatively convex subgroups
11/24/15 Tim Susse, UNL, Divergence, UFOs and random graphs
11/17/15 Delaram Kahrobaei, CUNY Graduate Center and City Tech, Conjugacy problem in metabelian and polycyclic groups: Complexity analysis
11/10/15 Kyle Istvan, Louisiana State U., The Kauffman polynomial of periodic links
11/3/15 George Mossessian, U. California - Davis, Common stabilizations of Heegaard splittings of knot complements
10/27/15 Aaron Calderon, UNL, Bipyramids and hyperbolic volume of tiling links
10/13/15 Susan Hermiller, UNL, Determining solvability of groups of homeomorphisms
9/29/15, 10/6/15 Maranda Franke, UNL, Dehn functions, I-II
9/22/15 Rob Kirby, U. California - Berkeley, Trisections of 4-manifolds
9/1/15, 9/8/15, 9/15/15 Alex Zupan, UNL, Knotted surfaces and bridge trisections, I-III
8/25/15 Organizational meeting

Spring 2015:

4/28/15 Anisah Nu'Man, UNL, Tame filling functions for groups and their closure properties
4/24/15 Ashley Johnson, U. North Alabama, Quasigroups and their (attempted) connections to geometric group theory
4/14/15 Matt Clay, U. Arkansas, Stable commutator length in Baumslag-Solitar groups
3/31/15, 4/7/15 Maranda Franke, UNL, An automata characterization of piecewise testable languages, I-II
3/10/15, 3/17/15 Nick Owad, UNL, Bridge number and bridge spectra, I-II
3/3/15 Yago Antolin Pichel, Vanderbilt U., Tits alternatives for graph products
2/17/15, 2/24/15 Robb Todd, U. Nebraska-Omaha, A cellular basis and the colored Jones polynomial, I-II
1/27/15, 2/10/15 Tim Susse, UNL, Special cube complexes, I-II

Fall 2014:

12/9/14 Muhammad Inam, UNL, Adian groups, semigroups, and inverse semigroups
12/2/14 Aaron Calderon, UNL, Braid groups and geodesic regularity
11/11/14, 11/18/14 John Meakin, UNL, Immersions of CW complexes, I-II
11/4/14 Anne Kerian, UNL, Bounds on crosscap number for alternating knots
10/28/14 Corbin Groothuis, UNL, A man, a plan, a canal, Panama!
10/14/14 Nick Owad, UNL, Making knots straight
10/7/14 Meggan Hass, UNL, Interpreting CAT(0) Spaces
10/3/14 Delaram Kahrobaei, CUNY Graduate Center and City Tech, The Conjugacy problem in polycyclic groups and applications to cryptography
9/23/14, 9/30/14 Maranda Franke, UNL, Hyperbolic spaces and their boundaries; Randomness in hyperbolic groups
9/16/14 Allison Beemer, UNL, On groups whose geodesic growth is polynomial
9/2/14, 9/9/14 Tim Susse, UNL, An Introduction to SCL, I-II
8/26/14 Organizational meeting

Spring 2014:

4/29/14 Natalie Rich, UNL, Intrinsic linking in directed graphs
4/22/14 Azer Akhmedov, North Dakota State U., Extension of Holder's Theorem in Diff1+ε(I)
4/21/14, 4/23/14 Maranda Franke, UNL, Groups, the theory of ends, and context-free languages, I-II
4/15/14 Tim Susse, CUNY Graduate Center, Stable commutator length in amalgamated free products
4/8/14 Jamie Radcliffe, UNL, The sprawl conjecture
3/18/14 Anne Kerian, UNL, Non-orientable spanning surfaces for knots
3/4/14, 3/11/14 Nick Owad, UNL, (Almost) All the ways to color knots, I-II
2/26/14 Conchita Martinez-Perez, U. Zaragoza, On centralizers of elements of 2V
2/14/14 David McCune, William Jewell C., Active context free games with finite target language
2/4/14 Pallavi Dani, Louisiana State U., Filling invariants: homological vs. homotopical
1/21/14 Mark Brittenham, UNL, Knots with multiple minimal genus spanning surfaces

Fall 2013:

12/10/13 Jamie Radcliffe, UNL, Groupoids
12/3/13 Robb Todd, U. Nebraska-Omaha, Some results and questions on t3 t4bar moves
11/19/13 Laura Ciobanu, U. Neuchatel, Relatively hyperbolic groups with the falsification by fellow traveller property
11/12/13 Melanie DeVries, UNL, Virtual regional crossing change
11/5/13 Nora Szakacs, UNL and U. Szeged, F-inverse covers of inverse monoids
10/29/13 Muhammad Inam, UNL, Automatic semigroups
10/15/13 John Meakin, UNL, Inverse automata, groups, and inverse semigroups
10/8/13 John Meakin, UNL, Automata, languages and semigroups
10/1/13 Susan Hermiller, UNL, Conjugacy languages in groups
9/24/13 Alex Kunin, UNL, Regular languages and finite automata
9/17/13 Maranda Franke, UNL, Small cancellation conditions
9/3/13, 9/10/13 Anisah Nu'Man, UNL, Filling functions for groups, I-II
8/27/13 Organizational meeting

Spring/Summer 2013:

6/26/13 Violeta Vasilevska, Utah Valley U., Rewriting systems for groups
Focus partial semester on amenable groups
4/23/13 Jamie Radcliffe, UNL, Amenability and Ramsey theory
4/9/13 Nathan Corwin, UNL, Amenability and Thompson's group F
4/2/13 Ashley Johnson, UNL, An introduction to amenable groups
3/26/13 John Meakin, UNL, Groups, semigroups and inverse semigroups: connections and contrasts
3/12/13 Anisah Nu'Man, UNL, Refinement of intrinsic and extrinsic diameter inequalities
3/5/13 Robb Todd, U. Nebraska - Omaha, Hecke Algebras, Temperley Lieb algebras and some interesting observations
2/26/13 Muhammad Inam, UNL, Maximal subgroups of free idempotent generated semigroups over bands
2/19/13 Melanie DeVries, UNL, An introduction to virtual braids
2/12/13 Mark Brittenham, UNL, Knot moves and knot group quotients
2/5/13 Ashley Johnson, UNL, Planar Cayley graphs
1/29/13 Maranda Franke, UNL, Braid groups
1/24/13 Morgan Cesa, U. Utah, Connections between geometry and group theory
1/15/13 Organizational meeting

Fall 2012:

12/4/12 Nick Owad, UNL, A preview of self-intersecting polygons
11/27/12 Melanie DeVries, UNL, Virtual knot theory
11/6/12, 11/20/12 Ashley Johnson, UNL, Results on autostackable groups, I-II
10/30/12 Jamie Radcliffe, UNL, Measure preserving words are primitive
10/23/12 Anisah Nu'Man, UNL, Decision problems for some finitely presented subgroups of Right Angled Artin Groups
10/9/12 John Meakin, UNL, A solution to the Hanna Neumann Cojecture
10/2/12 John Meakin, UNL, Stallings foldings and the Hanna Neumann conjecture
9/25/12, Chad Giusti, UNL, The (mod-two) cohomology of symmetric groups
9/18/12 Chad Giusti, UNL, Classifying spaces for discrete groups
9/11/12 Chad Giusti, UNL, Group cohomology
9/4/12 Susan Hermiller, UNL, Autostackable groups
8/28/12 Nathan Corwin, UNL, Dynamic facts about Thompson's group V
8/21/12 Organizational meeting

Spring 2012:

4/24/12 Susan Hermiller, UNL, Tame filling invariants
4/17/12 Derrick Stolee, UNL, Automorphism groups and adversarial vertex deletions
Focus third of a semester on Bass-Serre theory
4/10/12 Melanie DeVries, UNL, Bass-Serre theory, V
4/3/12 Ashley Johnson, UNL, Bass-Serre theory, IV
3/27/12 Nathan Corwin, UNL, Bass-Serre theory, III
3/13/12 Emily Ognacevic, UNL, Bass-Serre theory, II: Graphs of groups
3/6/12 Anne Kerian, UNL, Bass-Serre theory, I
2/21/12, 2/28/12 John Meakin, UNL, Semigroups generated by idempotent matrices, I-II
2/14/12 Anisah Nu'Man, UNL, Geodesics for Artin groups
1/24/12, 1/31/12 Mark Brittenham, UNL, A complete group-theoretic invariant for knots, after Nelson and Neumann, I-II
1/17/12 Robb Todd, U. Nebraska - Omaha, A novel application of semigroup theory: The yeast cell cycle
1/10/12 Organizational meeting

Fall 2011:

11/29/11, 12/6/11 Melanie DeVries, UNL, Virtual knots, I-II
11/15/11 Jamie Radcliffe, UNL, The exponential formula
11/8/11 Emily Ognacevic, UNL, Ordering graph products of groups
11/1/11 Mark Brittenham, UNL, Unknotting moves, and what (finite) group theory can tell us: the group theory part
10/25/11 Mark Brittenham, UNL, Unkotting moves for knots, and what finite group theory has to say about them
10/11/11 Nathan Corwin, UNL, (Failed) techniques on a conjecture in co-CF groups
9/20/11, 9/27/11, 10/4/11 Susan Hermiller, UNL, Stackable groups, I-III
8/30/11, 9/6/11, 9/13/11 Ashley Johnson, UNL, Computability and complexity, I-II, and III: The final voyage
8/23/11 Pascal Weil, U. Bordeaux, Asymptotic properties of finitely generated subgroups of free groups

Spring 2011:

Focus quarter semester on algorithms for groups
4/26/11 Melanie DeVries, UNL, Polycyclic presentations of groups
4/19/11 Carly Klivans, U. Chicago, Critical groups
4/12/11 David McCune, UNL Groups and semigroups generated by automata
4/5/11 Susan Hermiller, UNL, Further fundamental algorithms in group theory
3/29/11 Ashley Weatherwax, UNL, The Todd-Coxeter algorithm
3/15/11 Ashley Weatherwax, UNL, The finite presentation problem
Focus half semester on limit groups
3/8/11 Susan Hermiller and Mark Britteham, UNL, Introduction to JSJ and limit groups, VI
3/1/11 Mark Britteham and Susan Hermiller, UNL, Introduction to limit groups and JSJ, V
2/22/11 Mark Brittenham and David McCune, UNL, Introduction to limit groups, IV
2/15/11 David McCune, UNL, Introduction to limit groups, III
2/8/11 Susan Hermiller, UNL, Introduction to limit groups, II
2/1/11 Jamie Radcliffe, UNL, Introduction to limit groups
1/25/11 Organizational meeting
1/18/11 Andrew Duncan, U. Newcastle, UK, Automorphisms of right-angled Artin groups

Fall 2010:

12/7/10 Ashley Weatherwax, UNL, A brief history of the classification of finite simple groups, and solvability criterion for finite groups
11/23/10 Zoran Sunic, Texas A&M U., The conjugacy problems in automaton groups
11/16/10 Melanie DeVries, UNL, Finite complete rewriting systems for regular semigroups
11/9/10 Susan Hermiller, UNL, Groups with polynomial geodesic growth
11/2/10 Mark Brittenham, UNL, Low(est) volume hyperbolic manifolds (after Everitt, Ratcliffe, and Tschantz (and others))
10/26/10 Nathan Corwin, UNL, An inaccessible graph
10/12/10 Robb Todd, U. Nebraska - Omaha, The road coloring problem
9/28/10 Ashley Weatherwax, UNL, Hyperreflection groups
9/21/10 Lucas Sabalka, Binghamton U., On the geometry of the free splitting graph
9/7/10, 9/14/10 David McCune, UNL, Semigroups arising from asynchronous automata, I-II
8/31/10 Jamie Radcliffe, UNL, Diameters, distortion and eigenvalues
8/24/10 Organizational meeting

Spring 2010:

Focus half semester on reflections and hyperplane arrangements
4/27/10 Vladimir Itskov, UNL, A Geometric interpretation of the characteristic polynomial of central arrangements
4/20/10 Mark Brittenham, UNL, Improved lower bounds for the Reidemeister distance between knot diagrams (after Hass and Nowik)
4/13/10 Collin Bleak, UNL, Dynamical conditions and non-solvability in R. Thompson's group F
4/6/10 David McCune, UNL, Right-angled Coxeter groups and CAT(0) spaces
3/30/10 Susan Hermiller, UNL, Coxeter groups II: The Davis complex, infinite groups, and Euclidean and hyperbolic hyperplanes
3/23/10 Susan Hermiller, UNL, Coxeter groups I: Finite groups, spherical hyperplanes, and the Coxeter complex
3/8/10 Violeta Vasilevska, U. South Dakota, Different classes of Hopfian groups
Focus half semester on iterated monodromy groups
3/2/10 David McCune and Mark Brittenham, UNL, Introduction to iterated monodromy groups, VI
2/24/10 Mark Brittenham, UNL, Introduction to iterated monodromy groups, V
2/17/10 Bob Ruyle, UNL, Introduction to iterated monodromy groups, IV
2/10/10 Melanie DeVries, UNL, Introduction to iterated monodromy groups, III
2/3/10 Nathan Corwin, UNL, Introduction to iterated monodromy groups, II
1/26/10 Ashley Weatherwax, UNL, Introduction to iterated monodromy groups
1/12/10 Organizational meeting

Fall 2009:

12/10/09 Scott Dyer, UNL, The higher Grothendieck integral
11/24/09, 12/1/09 David McCune, UNL, Intermediate growth, I-II
11/19/09 David Yetter, Kansas State U., Deformations of monoidal categories and Vassiliev Theory
11/10/09 Robb Todd, U. Nebraska - Omaha, Mahler measure and repeated rational surgery
10/27/09 Susan Hermiller, UNL, More computational software for GST
10/13/09 David McCune, UNL, Introduction to GAP
Focus half semester on buildings
10/6/09 Mark Brittenham, UNL, Groups acting on buildings
9/29/09 Collin Bleak, UNL, Calculating the building for a linear algebraic group
9/22/09 Collin Bleak, UNL, What are buildings?
9/15/09 Collin Bleak, UNL, Wreath actions on high-dimensional cubes
9/1/09, 9/8/09 Robb Todd, U. Nebraska - Omaha, Foundations of buildings, I-II
8/24/09 Organizational meeting

Spring 2009:

4/28/09 David McCune, UNL, Nilpotent quotient algorithm
4/21/09, Violeta Vasilevska, U. South Dakota, Detecting approximate fibrations
4/14/09 Robb Todd, U. Nebraska - Omaha, Impromptu
3/31/09, 4/7/09 Susan Hermiller, UNL, Tame combings for groups, I-II
3/24/09 Robb Todd, U. Nebraska - Omaha Applications of Burnside groups in knot theory
3/3/09 Collin Bleak, UNL, A family of non-isomorphism results
2/24/09 Mark Brittenham, UNL, More groups in free idempotent-generated semigroups; or, Covering spaces really can be useful
2/19/09 Said Sidki, U. Brasilia, Brazil, Virtual endomorphisms of groups
1/20/09, 1/27/09, 2/3/09 John Meakin, UNL, Subgroups of semigroups generated by idempotents; or Groups, Semigroups *and* Topology! I-III
1/13/09 Organizational meeting

Fall 2008:

Focus half semester on laminations
12/2/08 Mark Brittenham, UNL, There is no algorithm to decide if a group is the fundamental group of a 3-manifold
11/18/08, 11/25/08 Scott Dyer, UNL, Untangling diffeomorphism for compact orientable 3-manifolds, I-II
11/4/08, 11/11/08 Robb Todd, U. Nebraska - Omaha, Seeing the forest through the leaves, I-II
10/28/08 Mark Brittenham, UNL, Foliations and laminations: The basics
Focus half semester on decision problems for groups
10/14/08 Olga Patricia Salazar Diaz, Universidad Nacional de Colombia, Revealing pairs, conjugacy, and R. Thompson's group V
10/7/08 Bob Ruyle, UNL, The conjugacy problem for braid groups
9/30/08 Collin Bleak, UNL, The conjugacy problem and the Grigorchuk group
9/23/08 Jamie Radcliffe, UNL, Bounding sizes of sumsets in commutative semigroups
9/16/08 Collin Bleak, UNL, The conjugacy problem for infinite groups
9/9/08 Andrew Ray, UNL, A group with unsolvable word problem
9/2/08 David McCune, UNL, The word problem and automaton groups
8/26/08 Organizational meeting

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

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

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