## Archive of Past Semesters

**Fall 2017**

- Sept 19 | Kim Ruane | Boundaries of CAT(0) IFP Groups
- Sept 26 | Corey Bregman | Abelian-by-Surface groups and Kaehler Manifolds
- Oct 3 | Sang-Hyun Kim | Free Products in
- Oct 10 | Emily Stark | The visual boundary of hyperbolic free-by-cyclic groups
- Oct 17 | Phil Wesolek | Tree almost automorphism groups: elements and subgroups
- Oct 24 | Ignat Soroko | Uncountably many quasi-isometry classes of groups of type FP
- Oct 31 | Arman Darbinyan | The word and conjugacy problems in lacunary hyperbolic groups
- Nov 7 | Kathryn Lindsey | Entropy, Galois conjugates, and postcritically finite maps
- Nov 14 | Nick Salter | Subgroups of the mapping class group via algebraic geometry
- Nov 21 | Joseph Maher | Random subgroups of acylindrical groups
- Nov 28 | Teddy Einstein | Hierarchies of Non-Positively Curved Cube Complexes
- Dec 5 | Meng-Che “Turbo” Ho | The word problem of a group as formal languages

**Spring 2017**

- Jan 24 | Ruth Charney (Brandeis) | Convexity of parabolic subgroups of Artin groups
- Feb 7 | Aaron Calderon (Yale) | Conjugacy geodesics in Coxeter groups
- Feb 21 | Pallavi Dani (LSU) | Commensurability classification for certain right-angled Coxeter groups
- Feb 28 | Assaf Bar Natan (McGill) | Arcs on punctured disks pairwise intersecting twice
- Mar 14 | Katie Mann (Berkeley) | Circular orders and the dynamics of group actions on the circle
- Mar 28 | Mary He (Chicago) | Basmajian-type identities and Hausdorff dimension of limit sets
- Mar 28 | Juliette Bavard (Chicago) | The Gromov boundary of the ray graph
- Apr 11 | Rob Kropholler (Tufts) | Subgroups of hyperbolic groups
- May 2 | Yago Antolin (Madrid) | The degree of commutativity for infinite groups, and its relatives

**Fall 2016**

- September 13, 2016 | Daniel Woodhouse (McGill/Technion) | Tubular groups: A history
- September 20, 2016 | Emily Stark (Technion) | Relatively hyperbolic surface group amalgams
- October 4, 2016 | Bena Tshishiku (Harvard) | The Wall conjecture and hyperbolic groups
- October 18, 2016 | Mark Pengitore (Purdue) | Precise residual finiteness of finitely generated nilpotent groups
- November 3, 2016 | François Dahmani (Grenoble/MSRI) | Some cases of the conjugacy problem in Out(F_n)
- November 8, 2016 | Josh Howie (Monash)
- November 15, 2016 | Daniel Studenmund (Utah) | Cohomology of the lamplighter group
- November 22, 2016 | Matthew Ryan Haulmark (UW Milwaukee)

**Spring 2016**

- February 2, 2016 | A factorization theorem for Fuchsian groups | Hao Liang (Tufts University)
- February 18, 2016 | No finite index subgroup of a mapping class group embeds into the C^2 circle diffeomorphism group | Sang-hyun Kim (Seoul National University)
- February 23, 2016 | Morse broken trajectories and hyperbolic volume | Hannah Alpert (MIT)
- March 15, 2016 | Intersections in the character variety of knot complements | Michelle Chu (University of Texas)
- March 29, 2016 | Curves on hyperbolic surfaces | Viveka Erlandsson (Fribourg)

and Coloring curves on surfaces | Nick Vlamis (Michigan) - April 19, 2016 | Effective characterization of Morse geodesics and stable subgroups | Tarik Aougab (Brown)

**Fall 2015**

- September 15 | Hung Tran (University of Wisconsin, Milwaukee) | “Relative divergence, subgroup distortion, and geodesic divergence”
- September 22 | Ian Biringer (Boston College) | “Ranks of mapping tori”
- October 1 | Chris Cashen (University of Vienna) | “Contracting geodesics in graphical small cancellation groups”
- October 13 | Matthew Cordes (Brandeis University) | TBA
- November 3 | Jessica Purcell (IAS) | “Cusp volumes of alternating knots”
- November 10 | Jing Tao (University of Oklahoma) | Effective quasimorphisms on right-angled Artin groups
- November 17 | Kim Ruane (Tufts University) | TBA
- December 1 | Daryl Cooper (IAS and University of California, Santa Barbara) | TBA
- December 8 | Jingyin Huang (Montreal) | TBA

**Spring 2015**

- January 20 | Bram Petri (Brown and Fribourg) | “Short curves on random surfaces”
- January 27 | Sarah Koch (Michigan and Harvard) | “Roots of polynomials and parameter spaces”
- February 3 | Martin Bridgeman (Boston College) | “Moments of the boundary hitting function for geodesic flow”
- February 10 | Valentina Disarlo (Indiana) | “The geometry of the flip graph”
- March 3 | Delaram Kahrobaei (City Tech/CUNY) | “The conjugacy problem in polycyclic groups”
- March 10 | Mark Hagen (Michigan) | “Hierarchically hyperbolic spaces and groups”
- March 24 | Hugo Parlier (Hunter and Fribourg) | “Chromatic numbers for hyperbolic surfaces”
- March 31 | Matt Durham (Michigan) | “Elliptic actions on Teichmüller space”
- April 7 | Eko Hironaka (Florida State and Harvard) | “Digraphs and entropy”
- April 14 | Jonah Gaster (Boston College) | “Curves on surfaces and Sageev’s dual cube complex”
- April 21 | Sarah Koch (Michigan and Harvard) | “Roots of polynomials and parameter spaces”

**Fall 2014**

- September 9 Meng-Che “Turbo” Ho (Wisconsin) “The 0-1 Conjecture for Groups”
- September 23 Sam Taylor (Yale) “Hyperbolic extensions of free groups”
- September 30 Andy Eisenberg (Tufts) “Recognizing right-angled Coxeter groups”
- October 7 Michael Carr (Brandeis) “2-generator subgroups of right-angled Artin groups”
- October 27 Peter Haissinsky (Toulouse) “Quasi-isometric rigidity of convex cocompact Kleinian groups”
- November 18 Khalid Bou-Rabee (CCNY/CUNY) “Normal systolic growths of linear groups”
- November 25 Jason Behrstock (Lehman/CUNY)
- December 2 Jen Taback (Bowdoin) “Quasi-isometry classification of Baumslag-Gersten groups”
- December 9 Sean Cleary (CCNY/CUNY) “Random subgroups and elements in Thompson’s group FF and common edges in triangulations”

**Spring 2014**

- February 4 Emily Stark (Tufts) “Quasi-isometric and commensurability classification of hyperbolic surface group amalgams”
- February 11 Igor Rivin (Temple and Brown) “Random manifolds”
- February 25 Sara Maloni (Brown) “Polyhedra inscribed in a hyperboloid and anti-de Sitter geometry”
- March 11 Jen Taback (Bowdoin) “Automorphisms of higher rank lamplighter groups”
- March 25 Bernhard Muehlherr (University Giessen) “Moufang multiple trees”
- April 1 Michael Shapiro (Tufts) “Equation Problems in Nilpotent Groups”
- April 8 Daniel Groves (UIC) “The Malnormal Special Quotient Theorem”
- April 15 *Rescheduled from March 4 Kim Ruane (Tufts) “Boundaries of CAT(0) Space with the Isolated Flats Property”
- April 29 Ken Baker (University of Miami) “Non-looseness of non-loose knots”
- May 20 Pallavi Dani (LSU) “Large-scale geometry of right-angled Coxeter groups”

**Fall 2013**

- September 24 Hao Liang (Tufts) “Equations over central extensions of hyperbolic groups”
- October 15 Asaf Hadari (Yale) “Homological shadows of attracting laminations”
- November 12 David Dumas (UIC) “Skinning maps and Lagrangian intersections: Theory and computation”
- November 26 Robert Tang (ICERM) “On various projection maps in the curve complex”
- December 3 Saul Schleimer (Warwick) “The boundary of the arc complex”

**Spring 2013**

- January 17 Neil Hoffman (Max Plank) “Hyperbolic knot complements and commensurability”
- January 29 Sang-hyun Kim (KAIST) “Hyperbolic aspects of right-angled Artin groups”
- February 12 Harold Sultan (Brandeis) “A spectrum of non-positive curvature”
- February 19 Anna Vijayan (Brandeis) “Compactification of the space of minimal actions of a right-angled Artin group”
- February 26 Joshua Greene (Boston College) “Conway mutation and alternating links”
- March 5 David Fried (Boston University) “Ideal Tilings and Symbolic Dynamics”
- March 12 Weiner Lecture
- March 26 Ian Biringer (Boston College) “Intersecting finite index subgroups of a group”
- April 2 Kasra Rafi (Toronto) “Large scale rank in Geometric Topology”
- April 16 Adam Piggott (Bucknell University) “Finite extensions of right-angled Coxeter groups”
- April 23 Steven Boyer (Montreal) “Foliations, left-orderability and L-spaces”
- April 30 Talia Fernos (University of North Carolina at Greensboro) “Rigidity of actions on CAT(0) cube complexes”

**Fall 2012**

- Sept 11 Mauricio Gutierrez (Tufts) “Subgroups of the automorphism group of a right-angled Artin group”
- Thursday Sept 13 Sa’ar Hersonsky (Georgia) “From tiling and packing to uniformization” (Colloquium)
- Sept 25 Ilesanmi Adeboye (Wesleyan) “Volume in complex hyperbolic geometry”
- Oct 2 Anders Karlsson (Geneva) “Two geometric boundaries of groups”
- Oct 9 Susan Hermiller (Nebraska) “Conjugacy growth series and languages for groups”
- Oct 23 Greg Kelsey (Trinity College) “Visual boundaries of Diestel-Leader graphs”
- Oct 30 Larry Guth (MIT) “The waist inequality in geometry and topology”
- Friday Nov 16, 4pm, BP 101 David Fisher (Indiana) “Rigidity of higher rank Anosov actions” (Colloquium)
- Nov 27 Genevieve Walsh (Tufts) “Right-angled Coxeter groups, polyhedral complexes, and acute triangulations”
- Dec 4 Zac Faubion (Tufts) “Independence and Large Cardinals”

**Spring 2012**

- January 31 Adam Levine (Brandeis) “Strong L-Spaces and Left-Orderability”
- February 7 Craig Hodgson (University of Melbourne) “On the number of hyperbolic 3-manifolds with a given volume”
- February 14 José Burillo (Universitat Politècnica de Catalunya) “On groups with polynomial geodesic growth”
- February 21 Harold Sultan (Columbia) “Hyperbolic directions in CAT(0) spaces”
- March 13 Christopher Mooney (Bradley) “Affine maps between CAT(0) spaces.”
- March 27 Dubi Kelmer (Boston College) “On the spectrum and length spectrum of hyperbolic manifolds”
- April 17 Craig Sutton (Dartmouth) “You can’t hear the covering spectrum of a manifold”

**Fall 2011**

- September 13 | Ruth Charney (Brandeis) | “Introduction to CAT(0) cube complexes”
- September 20 | Boris Hasselblatt (Tufts) | “Poisson boundaries”
- September 27 | Will Cavendish (Princeton) | “Finite-sheeted covering spaces of 3-manifolds and engulfed subgroups.”
- October 4 | Mohammed Abouzaid (MIT and Clay Math Institute) | “Application of Floer theory to Lagrangian embeddings”
- October 11 | Kim Ruane and Moon Duchin (Tufts) | “Boundaries: the visual, Tits, and Roller boundaries”
- October 25 | Kim Ruane (Tufts) | “More on Boundaries”
- November 1 | Thomas Koberda (Harvard) | “Teichmüller polynomials, Alexander polynomials and finite covers of surfaces”
- November 8 | Lluís Alsedà (Barcelona)
- November 15 | Johanna Mangahas (Brown) | “The geometry of right-angled Artin subgroups of mapping class groups.”
- November 29 | Joseph Maher (CUNY Staten Island) | “Growth rates for stable commutator length.”
- December 6 | Ian Biringer (Yale) | “Geometry of Hyperbolic 3-Manifolds with Constrained Rank.”
- December 9 | Dani Wise (McGill) | “Quasiconvex Subgroups of Relatively Hyperbolic groups.”
- December 13 | Ruth Charney (Brandeis) | “Contracting boundaries of CAT(0) spaces”

**Spring 2011**

- Feb 15 Jonathan Bloom (Columbia and MIT) “Links, monopoles, and mutation”
- March 1 Genevieve Walsh (Tufts) “Coxeter groups, surfaces, and 3-manifolds”
- March 15 Guterman lecture: John Meier (Lafayette)
- March 18 Keith Burns (Northwestern) “Ergodicity of the Weil Petersson Geodesic Flow” (joint with Colloquium)
- March 29 Thomas Koberda (Harvard) “Mapping classes and homology of finite surfaces”
- April 7 Jesse Johnson (Oklahoma State) “Mapping class groups of Heegaard splittings”
- April 12 Neil Hoffman (University of Texas) “Hidden symmetries, exceptional surgeries and commensurability”
- April 19 Kieran Roberts (University of Birmingham) “Simple Lie algebras generated by extremal elements.”
- April 26 Jennifer Taback (Bowdoin) “Metric properties of horocyclic products of trees”

**Fall 2010**

- December 14 Joel Louwsma (Caltech) “Immersed surfaces in the modular orbifold”
- November 30 Ruth Charney (Brandeis) “Divergence in right-angled Artin groups”
- November 2 Vaibhav Gadre (Harvard) “Bounds on the minimal translation length for pseudo-Anosov maps in the curve complex.”
- October 19 Jeff Carlson (Tufts) “Some commensurable and incommensurable pseudo-Anosovs”
- October 5 Aaron Brown (Tufts) “Groups preserving measures”
- September 21 Thomas Koberda (Harvard) “Right angled Artin groups and mapping class groups”
- September 14 Sang-hyun (Sam) Kim (Tufts) “Polygonality and Surface Subgroups”

**Spring 2010**

- April 30 2:30 Dave Futer (Temple) “Cusp volume of fibered 3-manifolds”
- April 16 Adam Piggott (Bucknell) “On the Derived Series of Coxeter Groups” (Colloquium)
- April 13 Ronen Mukamel (MIT) “Orbifold points on Teichmueller curves in genus two”
- April 5,6,7 Robert Ghrist (UPenn) Norbert Wiener Lecture Series
- March 30 Jeff Carlson (Tufts) Discussion of: “On Fibered Ccommensurability” by Calegari, Sun, and Wang
- March 2 Thomas Barthelme (Tufts) “A natural generalization of the Laplace operator to Finsler geometry”
- February 19 Sergio Fenley (FSU) Colloquium
- February 18 Jason Behrstock (CUNY Lehman College) “Quasi-isometric classification of 3-manifold groups”
- February 9 Sungmo Kang (Boston College) “Hyperbolic knots in S3S3 with lens space and Seifert fibered surgeries”

**Fall 2009**

- September 15 Zbigniew Nitecki (Tufts) “Reducibility of mapping classes via braid theory I”
- September 18 Eriko Hironaka (Florida State) “Lehmer’s problem and dynamics on surfaces” (Colloquium)
- September 22 Elisenda Grigsby (Boston College) “On Khovanov and Heegaard Floer homology”
- September 29 Zbigniew Nitecki (Tufts) “Reducibility of mapping classes via braid theory II”
- October 6 3pm Jason Manning (Buffalo) “Virtually geometric words and Whitehead’s algorithm”
- October 6 4:15pm Robert Young (NYU and IHES) “The Dehn function of SL(n,ℤ)SL(n,Z)“
- October 16 Kevin Wortman (Utah) Colloquium
- October 19 – 22 Clay Math Institute Workshop on Outer Space
- October 27 Joseph Maher (CUNY College of Staten Island) “Generic elements in the mapping class group”
- November 3 Mauricio Gutierrez (Tufts) “Generators for the automorphism group of a graph product”
- November 10 Thomas Koberda (Harvard) “Residual properties of certain 3-manifold groups”
- November 17 Kim Ruane (Tufts) “A proof that deserves a better theorem…”
- December 1 Sarah Koch (Harvard) “Thurston’s Pullback Map”
- December 8 Richard Weiss (Tufts) “Groups acting on Trees”

**Spring 2009**

- January 27 Kim Ruane (Tufts) “Groups acting on CAT(0) cube complexes”
- January 30 Ruth Charney (Brandeis) “Groups and their automorphisms, from free to free abelian” (Colloquium)
- February 3 Jennifer Taback (Bowdoin) “Twisted conjugacy classes of lamplighter groups”
- February 10 Thomas Church (Chicago) “Groups of mapping classes that cannot be realized by diffeomorphisms”
- February 13 Joan Birman (Columbia) “Lorenz links, twisted torus links and modular knots” (Colloquium)
- February 17 Genevieve Walsh (Tufts) “Commensurability of knot complements”
- February 20 Thomas Banchoff (Brown) “Exploring Surfaces in Three and Four Dimensions” (Colloquium/Guterman Lecture)
- February 27 Mark Behrens (MIT) “Modular forms in topology” (Colloquium)
- March 31 Dan Margalit (Tufts) “Braid groups, spin groups, and Torelli groups”
- April 6 Karin Melnick (Yale) “An embedding theorem for Cartan geometries”
- April 10 Sergio Fenley (Florida State) Colloquium
- April 21 Andy Putman (MIT) “On the self-intersections of curves deep in the lower central series of a surface group”
- April 28 Dan Margalit (Tufts) “Low-dilatation pseudo-Anosovs and 3-manifolds”

**Fall 2008**

- September 9 Mauricio Gutierrez (Tufts) “The Centralizer Theorem for Graph Products of Abelian Groups”
- September 16 Kim Ruane (Tufts) “A geometric model for Aut(F2)(F2))”
- September 22, 23, 24 Jeff Weeks (independent), Norbert Wiener Lecture Series, “The Shape of Space”
- September 30 Dan Margalit (Tufts) “Low dimensional homologies of mapping class groups”
- October 7 Andy Putman (MIT) “The second rational homology group of the moduli space of curves with level structures”
- October 14 Richard Weiss (Tufts) “Buildings of rank 2”
- October 21 Thomas Koberda (Harvard) “Homological representations of mapping classes”
- October 28 Richard Kent (Brown) “Inequalities in free groups”
- November 11 Helen Wong (Bowdoin) “The mapping class group, Heegaard splittings, and quantum invariants for 3-manifolds”
- November 18 3pm Talia Fernos (UCLA) “On Relative Property (T)”
- November 18 4:15pm Kai-Uwe Bux (Virginia) “Thompson’s group V is linear (or at least, it should be)”
- November 25, 2008 Dan Margalit (Tufts) “Free groups in the pure braid group”
- December 2 Natasa Macura (Trinity University and Brandeis) “CAT(0) spaces with polynomial divergence of geodesics”
- December 8 Bridget Tenner (DePaul) “Coxeter groups and Bruhat order: algebraic and topological structure” (Colloquium)

**Spring 2008**

- May 6 Edward Taylor (Wesleyan) “The Quasiconformal Homogeneity of Hyperbolic Manifolds”
- April 29 Matthew Day (Chicago) “Finite generation of subgroups of automorphism groups of right-angled Artin groups”
- April 22 Keith Burns (Northwestern)
- April 15 Ki Hyoung Ko (KAIST) “Graph braid groups and right-angled Artin groups”
- April 8 Tim Riley (Bristol) “Hydra Groups”
- April 1 Robert Meyerhoff (Boston College)
- March 25 Daniel Ruberman (Brandeis) “Fundamental groups of surface complements”
- March 11 Genevieve Walsh (Tufts) “Residually finite rational solvable groups, right-angled Coxeter groups, and the virtually fibered conjecture”
- February 26 Colin Adams (Williams) “Quasi-Fuchsian surfaces in noncompact hyperbolic 3-manifolds”
- February 19 Andrew Putman (MIT) “Subgroup distortion in the mapping class group”

**Fall 2007**

- December 4 James Propp (UMass Lowell) “Chip-firing groups and fractal structures arising from graph-Laplacians”
- November 27 Petra Hitzelberger (Münster and Tufts) “Buildings having octagons as boundary”
- November 20 Michael Shapiro (Tufts Medical School) “Groups that do not have Cannon’s algorithms”
- November 13 Yvonne Lai (UC Davis) “An effective compactness theorem for Coxeter groups”
- November 6 Ki Hyoung Ko (KAIST) “A polynomial-time solution to the reducibility problem of braid groups”
- October 23 Richard Weiss (Tufts) “Locally finite affine buildings”
- October 16 Tao Li (Boston College) “Heegaard splittings of amalgamated 3-manifolds and distance in the curve complex”
- October 10 James W. Cannon (BYU) “Constructing random 3-manifolds”
- October 2 Shawn Rafalski (Williams) “Immersed Hyperbolic Turnovers”
- September 25 Daniel Ruberman (Brandeis) “Knot concordance and Heegaard-Floer invariants in branched covers”
- September 18 Kim Ruane (Tufts) “Automorphisms of Graphs of Groups”
- September 4 Yoav Segev (Ben Gurion) “The root groups of special Moufang sets”

**Spring 2007**

- April 24 Patrick Bahls (UNC Asheville) “Asymptotic connectivity and the geometry of a graph”
- April 17 Dmitriy Sonkin (UVA) “Limits of hyperbolic groups and uniform Kazhdan groups”
- April 10 Stephan Tillmann (Melbourne) “The Thurston norm via normal surfaces”
- April 3 Sarah Rees (Newcastle-Upon-Tyne) “Group geodesics: regularity, star-freedom and local testability”
- April 3 Jason Behrstock (Utah) “Dimension and rank of mapping class groups”
- March 27 Adam Piggott (Tufts) “Rigidity of graph products of abelian groups”
- March 13 Jennifer Taback (Bowdoin) “Asymptotic density of subgroups of Thompson’s group F”
- March 6 Matthew Hedden (MIT) “Lens space surgeries and complex curves”
- February 27 Petra Hitzelberger (Münster) “A convexity theorem for affine buildings”
- February 20 Genevieve Walsh (Tufts) “Commensurability and Knot Complements”
- February 13 Stefan Friedl (UQAM) “Symplectic 4-manifolds and subgroup separability”
- February 6 Martin Bridgeman (Boston College) “Hausdorff dimension under bending deformations and the Weil-Petersson metric”
- January 30 Mark O’Brien (Tufts) “STUF”
- January 23 Mark O’Brien (Tufts) “Right-angled Coxeter Pairs”

**Fall 2006**

- December 5 Adam Piggott (Tufts) “Presenting the Automorphism Group of a ‘Tree Product’ of Primary Cyclic Groups.”
- November 28 Adam Piggott (Tufts) “On the Automorphisms of Graph Products of Cyclic Groups.”
- November 14 Mauricio Gutierrez (Tufts) “The conjugating automorphisms of a graph products of groups”
- November 7 Ruth Charney (Brandeis) “Relative hyperbolicity and Artin groups”
- October 24 Michael Shapiro (Tufts Medical School) “Dehn’s algorithms for non-hyperbolic groups II”
- October 10 Michael Shapiro (Tufts Medical School) “Dehn’s algorithms for non-hyperbolic groups I”
- October 3 Kim Ruane (Tufts) “Relative Hyperbolicty II”
- September 26 Murray Elder (Stevens) “D-finiteness and Group Growth.”
- September 19 Kim Ruane (Tufts) “Relative Hyperbolicty”