Papers

Click after the title to see the paper (requires either a dvi or ps viewer).
NOTE: Figures appear only in the ps and pdf files.

• The Grothendieck-Katz Conjecture for certain locally symmetric varieties ps or pdf
  (with M. Kisin), preprint, 7 pages, July 2008.
  
  
• Group actions and Helly's theorem ps or pdf
  preprint, 17 pages, June 2008.
  
  
• The intrinsic asymmetry and inhomogeneity of Teichmuller space. ps or pdf
  (with S. Weinberger), preprint, 8 pages, April 2008.
  
  
• Problems on automorphism groups of nonpositively curved
  polyhedral complexes and their lattices. ps or pdf
  (with C. Hruska and A. Thomas), preprint, 38 pages, March 2008.
  
  
• Teichmuller geometry of moduli space, I: Distance minimizing rays and
  the Deligne-Mumford compactification. ps or pdf
  (with H. Masur), preprint, 44 pages, Feb 2008.
  
  
• Irreducible Sp-representations and subgroup distortion in the
  mapping class group. ps or pdf
  (with N. Broaddus and A. Putman), preprint, 29 pages, July 2007.
  
  
• The Casson invariant and the word metric on the Torelli group. ps or pdf
  (with N. Broaddus and A. Putman), C.R. Acad. Sci Paris, Vol. 345 (2007), no. 8, 449--452.
  
  
• Commensurations of Out(F_n). ps or pdf
  (with Michael Handel), Publ. Math. IHES., No. 105 (2007), 1--48.
  
  
• (Book) Problems on Mapping Class Groups and Related Topics. pdf
  This is a (June 2006) version of a book that appeared as Proc. Symp. Pure and Applied Math., Volume 74, 2006.
  It is the final online version. 402 pages.
  
  
• Some problems on mapping class groups and moduli space. dvi or ps or pdf
  in ``Problems on Mapping Class Groups and Related Topics",
  ed. by B. Farb, Proc. Symp. Pure and Applied Math., Vol. 74, pp. 11-55, June 2006.
  
  
• The lower central series and pseudo-Anosov dilatations. ps or pdf
  (with C. Leininger and D. Margalit), to appear in American Jour. Math.
  
  
• The Birman-Craggs-Johnson homomorphism and abelian cycles in the Torelli group. dvi or ps or pdf
  (with T. Brendle), Math. Annalen, 338 (2007), no. 1, 33--53.
  
  
• Isometries, rigidity and universal covers. dvi or ps or pdf
  (with S. Weinberger), revised Dec. 2006, to appear in Annals of Math.
  
  
• Commensurability invariants for nonuniform tree lattices. dvi or ps or pdf
  (with C. Hruska), Israel Jour. Math. 152 (2006), 125--142.
  
  
• K_g is not finitely generated. dvi or ps or pdf
  (with D. Biss), Inventiones Math. Vol. 163, pp. 213--226 (2006).
  
  
• Hidden symmetries and arithmetic manifolds. dvi or ps or pdf
  (with S. Weinberger), in Geometry, spectral theory, groups, and dynamics , Contemp. Math., Vol. 387, Amer. Math. Soc., pp. 111--119.
  
  
• The Torelli Geometry and its applications. dvi or ps or pdf
  (with N. Ivanov), Math. Research Letters., Vol. 12, pp. 293-301 (2005).
  
  
• Every mapping class group is generated by 6 involutions. dvi or ps or pdf
  (with T. Brendle), Journal of Algebra. , Vol. 278 (2004), 187-198.
  
  
• Some recent applications of the barycenter method in geometry. dvi or ps or pdf
  (with C. Connell), in Topology and Geometry of Manifolds , Proc. Symp. in Pure Math., G. Matic and C. McCrory, Eds., 2003, 19--51.
  
  
• The Degree Theorem in higher rank. dvi or ps or pdf
  (with C. Connell), J. Diff. Geom., Vol. 65 (2003), 19--59.
  
  
• Real-analytic, volume-preserving actions of lattices on 4-manifolds. dvi or ps or pdf
  (with P. Shalen), C.R. Acad. Sci Paris, Ser. I, Vol. 334 (2002), 1011-1014.
  
  
• Curvature and rank of Teichmuller space. dvi or ps or pdf
  (with J. Brock), American Jour. Math. , Vol. 128, No. 1 (2006), pp. 1-22.
  
  
• Groups of homeomorphisms of one-manifolds, III: Nilpotent subgroups. dvi or ps or pdf
  (with J. Franks), Ergodic Theory Dynam. Systems 23 (2003), no. 5, 1467--1484
  
  
• Convex cocompact subgroups of mapping class groups. dvi or ps or pdf
  (with L. Mosher), Geometry and Topology, Vol. 6 (2002), 91-152.
  
  
• Groups of homeomorphisms of one-manifolds, I: Actions of nonlinear groups . dvi or ps or pdf
  (with J. Franks), June 2001 preprint, 28 pages.
  
  
• Groups of homeomorphisms of one-manifolds, II: Extensions of Holder's Theorem. dvi or ps or pdf
  (with J. Franks), Trans. Amer. Math. Soc. , Vol. 355 (2003), no. 11, 4385--4396.
  
  
• A strong Schottky Lemma for nonpositively curved singular spaces. dvi or ps or pdf
  (with R. Alperin and G. Noskov), Geometriae Dedicata , Vol. 92 (2002), 235--243.
  
  
• The geometry of surface-by-free groups. dvi or ps or pdf
  (with L. Mosher), Geom. Funct. Anal (GAFA), Vol.12 (2002), no. 5, 915--963.
  
  
• Minimal entropy rigidity for lattices in products of rank one symmetric spaces. dvi or ps or pdf
  (with C. Connell). Comm. in Anal. and Geom. 11 (2003), no. 5, 1001--1026.
  
  
• Rank one phenomena for mapping class groups. dvi or ps or pdf
  (with A. Lubotzky and Y. Minksy). Duke Math Journal, Vol. 106, No.3 (2001), 581-597.
  
  
• Problems on the geometry of finitely generated solvable groups. dvi or ps or pdf
  (with L. Mosher), in ``Crystallographic Groups and their Generalizations (Kortrijk, 1999)'', (ed. P. Igodt, et. al.), Cont. Math. 262, Amer. Math. Soc. (2000).
  
  
• On the asymptotic geometry of abelian-by-cyclic groups. dvi or ps or pdf
  (with L. Mosher). Acta Math. , Vol. 184, No.2 (2000), 145-202.
  
  
• Groups of real-analytic diffeomorphisms of the circle. dvi or ps
  (with P. Shalen). Ergodic Theory and Dynam. Syst. , Vol. 22 (2002), 835-844.
  
  
• Lattice actions, 3-manifolds, and homology. dvi or ps
  (with P. Shalen). Topology , Vol. 39 (2000), no. 3, 573-587.
  
  
• Real-analytic actions of lattices. dvi or ps
  (with P. Shalen). Inventiones Math. , Vol. 135 (1998), 273-296.
  
  
• A remark about actions of lattices on free groups. dvi or ps
  (with M. Bridson). Topology Appl. , Vol. 110, No. 1 (2001), 21-24.
  
  
• Harmonic splittings of surfaces. dvi or ps
  (with M. Wolf). Topology, Vol. 40, No.6 (2001), 1395-1414.
  
  
• Superrigidity and mapping class groups. dvi or ps
  (with H. Masur). Topology , Vol. 37, No.6 (1998), 1169-1176.
  
  
• Quasi-isometric rigidity for the solvable Baumslag-Solitar groups, II. dvi or ps
  (with L. Mosher) Inventiones Math. , Vol. 137 (1999), No. 3, 273-296.
  
  
• The quasi-isometry classification of lattices in semisimple Lie groups. dvi or ps
  Math. Res. Letters, Vol. 4, No.5, Sept. 1997, 705-718.
  
  
• A rigidity theorem for the solvable Baumslag-Solitar groups. dvi or ps
  (with L. Mosher). Inventiones Math. , Vol. 131, No.2 (1998), 419-451.
  
  
• Quasi-flats and rigidity in higher rank symmetric spaces. dvi or ps
  (with A. Eskin). Journal AMS. , Vol. 10, No.3, July 1997, 653-692.
  
  
• Quasi-flats in H²xH². dvi or ps
  (with A. Eskin). Proceedings of the International Colloquium on Lie groups and Ergodic Theory, Tata Institute 1996.
  
  
• The large-scale geometry of Hilbert modular groups. dvi or ps
  (with R. Schwartz). J. Diff. Geom. 44, No.3 (1996), 435-478.
  
  
• Relatively hyperbolic groups. dvi or ps
  Geom. Funct. Anal. (GAFA), Vol.8 (1998), 1-31.
  
  
• Filling-invariants at infinity for manifolds of nonpositive curvature. dvi or ps
  (with N. Brady). Trans. Amer. Math. Soc., Vol.350, No.8 (1998), 3393-3405.
  
  
• Relatively hyperbolic and automatic groups with applications to negatively curved manifolds.
  Thesis, Princeton University, May 1994.
  
  
• Combing lattices in semisimple Lie groups. dvi or ps
  Groups - Korea '94, Proceedings of the international conference, ed. by A.C. Kim and D.L. Johnson, deGruyter 1994, 57-67.
  
  
• The Extrinsic geometry of subgroups and the generalized word problem. dvi or ps
  Proc. London Math. Soc. (3) 68 (1994), 577-593.
  
  
• (Book)Noncommutative Algebra.
  (book with R.K. Dennis), Graduate Texts in Mathematics 144, 270 pages, Springer, New York, 1993.
  
  
• Automatic groups: A guided tour. dvi or ps
  L'Enseignement Math., Vol. 38 (1992), 291-313.