Work in progress

Preprints

[68]  On free-group algorithms that sandwich a subgroup between free-product factors. 14 pages.        arXiv
[67]  Simplified Mineyev. 2 pages.
        Reworking of my email to Igor Mineyev which gave a one-page simplification of his May 7, 2011,
        twenty-page, Hilbert-module-theoretic proof of the strengthened Hanna Neumann conjecture, which
        had been proved six days earlier by Joel Friedman.

Publications to appear

[66]  Joel Friedman's proof of the strengthened Hanna Neumann conjecture.
        in Joel Friedman, Sheaves on graphs, their homological invariants, and a proof of
        the Hanna Neumann conjecture: with an appendix by Warren Dicks
         Mem. of the AMS. (to appear).
[65] (with Pere Ara)
        Ring coproducts embedded in power-series rings.         arXiv
        Forum Math. (to appear).
[64] (with Conchita Martínez-Pérez)
        Isomorphisms of Brin-Higman-Thompson groups.         arXiv
        Israel J. Math. (to appear).

Research publications

[63] (with David J. Wright)
        On hyperbolic once-punctured-torus bundles IV: automata for lightning curves.         CRM preprint
        Topology Appl. 159 (2012), 98-132.
                Subscribers to ScienceDirect can download the article.
[62] (with Lluís Bacardit)
        The Zieschang-McCool method for generating algebraic mapping-class groups.         arXiv
        Groups -- Complexity -- Cryptology 3 (2011), 187–220.
                Subscribers to de Gruyter can download the article.
[61] (with Yago Antolín and Peter A. Linnell)
        The local-indicability Cohen-Lyndon theorem.         arXiv
        Glasgow Math. J. 53 (2011), 637–656.
                Subscribers to the Glasgow Math. J. can download the article.
[60] (with S. V. Ivanov)
        On the intersection of free subgroups in free products of groups with no 2-torsion.
        Illinois J. Math. 54 (2010), 223-248.         (Issue in honor of Paul Schupp).
[59] (with Yago Antolín and Peter A. Linnell)
        Non-orientable surface-plus-one-relation groups.         arXiv
        J. Algebra 326 (2011), 4–33.
                Subscribers to ScienceDirect can download the article.
[58] (with Makoto Sakuma)
        On hyperbolic once-punctured-torus bundles III: comparing two tessellations of the complex plane.         arXiv
        Topology Appl. 157 (2010), 1873-1899.
                Subscribers to ScienceDirect can download the article.
[57] (with Lluís Bacardit)
        Actions of the braid group, and new algebraic proofs of results of Dehornoy and Larue.         arXiv
        Groups -- Complexity -- Cryptology 1 (2009), 77-129.
               Subscribers to deGruyter ReferenceGlobal can download the article.
[56] (with S. V. Ivanov)
        On the intersection of free subgroups in free products of groups.         arXiv         CRM preprint
        Math. Proc. Cambridge Philos. Soc., 144 (2008), 511-534.
               Subscribers to the Math. Proc. Cambridge Philos. Soc. can download the article.
[55] (with M. J. Dunwoody)
        Retracts of vertex sets of trees and the almost stability theorem.         arXiv
        J. Group Theory, 10 (2007), 703-721.
               Subscribers to deGruyter ReferenceGlobal can download the article.
[54] (with Peter A. Linnell)
        L ²-Betti numbers of one-relator groups.         arXiv
        Math. Ann., 337 (2007), 855-874.
               Subscribers to SpringerLink can download the article.
[53] (with Pere Ara)
        Universal localizations embedded in power-series rings.
        Forum Math., 19 (2007), 365-378.
               Subscribers to deGruyter ReferenceGlobal can download the article.
[52] (with James W. Cannon)
        On hyperbolic once-punctured-torus bundles II: fractal tessellations of the plane.         CRM preprint
        Geom. Dedicata, 123 (2006), 11-63.
               Subscribers to SpringerLink can download the article.
    Errata and addenda (October 11, 2007)
[51] (with Laura Ciobanu)
        Two examples in the Galois theory of free groups.         CRM preprint
        J. Algebra, 305 (2006), 540–547.
                Subscribers to ScienceDirect can download the article.
[50] (with Edward Formanek)
        Algebraic mapping-class groups of orientable surfaces with boundaries.         CRM preprint
        pp. 57-116, in: Infinite groups: geometric, combinatorial and dynamical aspects
        (Editors: Laurent Bartholdi, Tullio Ceccherini-Silberstein, Tatiana Smirnova-Nagnibeda, Andrzej Zuk),
        Progress in Mathematics 248,  Birkhäuser Verlag, Basel, Switzerland, 2005.
    Errata and addenda (September 28, 2007)
               Subscribers to SpringerLink can download the article.
[49] (with Dolors Herbera and Javier Sánchez)
        On a theorem of Ian Hughes about division rings of fractions.
        Comm. Algebra, 32 (2004), 1127-1149.   MR2005h:16043
                Subscribers to Taylor & Francis can download the article.
[48] (with J. Porti)
        On the Hausdorff dimension of the Gieseking fractal.
        Topology Appl., 126 (2002), 169-186.   MR2003h:57017
    Addenda (May 1, 2005)
                Subscribers to ScienceDirect can download the article.
[47] (with James W. Cannon)
        On hyperbolic once-punctured-torus bundles.         preprint
        Geom. Dedicata 94 (2002), 141-183.   MR2004a:57038
    Errata and addenda  (September 28, 2007)
               Subscribers to SpringerLink can download the article.
[46] (with Thomas Schick)
        The spectral measure of certain elements of the complex group ring of a wreath product.         arXiv
        Geom. Dedicata 93 (2002), 121-137.  MR2003i:20005
    Addenda (May 30, 2008)
               Subscribers to SpringerLink can download the article.
[45] (with Peter H. Kropholler, Ian J. Leary, and Simon Thomas)
        Classifying spaces for proper actions of locally finite groups.         arXiv         preprint
        J. Group Theory, 5 (2002), 453-480.   MR2003g:20064  
    Addenda (May 30, 2002)
               Subscribers to deGruyter ReferenceGlobal can download the article.
[44] (with Edward Formanek)
        The rank three case of the Hanna Neumann conjecture.
        J. Group Theory, 4 (2001), 113-151.   MR2002e:20051
               Subscribers to deGruyter ReferenceGlobal can download the article.
[43] (with M. J. Dunwoody)
        On equalizers of sections.
        J. Algebra, 216 (1999), 20-39.   MR2000g:20040
               Subscribers to ScienceDirect can download the article.
[42] (with R. C. Alperin and J. Porti)
        The boundary of the Gieseking tree in hyperbolic three-space.
        Topology Appl., 93 (1999), 219-259.   MR2000d:57024
               Subscribers to ScienceDirect can download the article.
[41] (with Ian J. Leary)
        Presentations for subgroups of Artin groups.
        Proc. Amer. Math. Soc. 127 (1999), 343-348.   MR99c:20050
[40] Erratum: W. S. Jassim, On the intersection of finitely generated subgroups of free groups.
        Rev. Mat. Univ. Compl. Madrid 11 (1998), 263-265.   MR99m:20046
[39] (with J. Porti)
        Expressing a number as the sum of two coprime squares.
        Collect. Math.49 (1998), 283-291.   MR2000b:11038
   Addenda (December 3, 1999)
[38] (with Ian J.Leary)
        On subgroups of Coxeter groups.
        pp. 124-160 in: Geometry and cohomology in group theory
        (Editors: Peter H. Kropholler, Graham A. Niblo and Ralph Stöhr),
        LMS Lecture Note Ser. 252, CUP, Cambridge, 1998.   MR2000g:20067
[37] (with H. H. Glover)
        An algorithm for cellular maps of surfaces.
        Enseign. Math. (2) 43 (1997), 207-252.   MR99e:57001
[36] (with Edward Formanek)
        Automorphism subgroups of finite index in algebraic mapping class groups.
        J. Algebra 189 (1997), 58-89.   MR98b:20057
    Errata and addenda  (October 2, 2003)
               Subscribers to ScienceDirect can download the article.
[35*] (with Enric Ventura)
        The group fixed by a family of injective endomorphisms of a free group.
        Contemporary Math., 195. Amer. Math. Soc., Providence, RI, 1996. x+81pp.   MR97h:20030
    Errata and addenda (April 21, 2009)
               Subscribers to the American Mathematical Society can download the book.
[34] (with Jaume Llibre)
        Orientation-preserving self-homeomorphisms of the surface of genus two have points of period at most two.
        Proc. Amer. Math. Soc. 124(1996), 1583-1591.   MR96g:55004
[33] (with Peter H. Kropholler)
        Free groups and almost equivariant maps.
        Bull. London Math. Soc. 27 (1995), 319-326. MR96e:20031
   Addenda (January 24, 2000)
                Subscribers to the Bulletin of the London Mathematical Society Online can download the article.
[32] Equivalence of the strengthened Hanna Neumann conjecture and the amalgamated graph conjecture.
       Invent. Math. 117 (1994), 373-389.   MR95c:20034
   Errata (October 21, 2003)
               Subscribers to SpringerLink can download the article.
[31] (with Ian J. Leary)
        Exact sequences for mixed coproduct/tensor-product ring constructions.                The original preprint by George M. Bergman.
        Publ. Mat. 38 (1994), 89-126.   MR96a:16026
[30] (with Enric Ventura)
        Irreducible automorphisms of growth rate one.
        J. Pure Appl. Algebra 88 (1993), 51-62.   MR94i:20047
               Subscribers to ScienceDirect can download the article.
[29] (with Rosa Camps)
        On semilocal rings.                First edition                Second edition
        Israel J. Math. 81 (1993), 203-211.   MR94m:16027
                Subscribers to SpringerLink can download the article.
[28] (with Carles Casacuberta)
       On finite groups acting on acyclic complexes of dimension two.
       Publ. Mat. 36 (1992), 463-466.   MR94c:55006
[27] (with B. Hartley)
       On homomorphisms between special linear groups over division rings.
       Comm. Algebra 19 (1991) 1919-1943.   MR92f:20048
       Errata and addenda. Comm. Algebra 22 (1994), 6493-6494.   MR95k:20076
                Subscribers to Taylor & Francis can download the article and also the errata and addenda
[26*] (with M. J. Dunwoody)
         Groups acting on graphs.
         Cambridge Studies in Advanced Mathematics 17, CUP, Cambridge, 1989. xvi+283pp.   MR91b:20001
   Errata (January 31, 2008)
[25] On a characterization of Azumaya algebras.
        Publ. Mat. 32 (1988), 165-166.   MR90b:16006
   Errata and addenda (March 10, 2003)
[24] (with A. H. Schofield)
       On semihereditary rings.
       Comm. Algebra 16 (1988), 1243-1274.   MR89e:16009
                Subscribers to Taylor & Francis can download the article.
[23] On the cohomology of one-relator associative algebras.
        J. Algebra 97 (1985), 79-100.   MR87h:16041
               Subscribers to ScienceDirect can download the article.
[22] Homogeneous elements of free algebras have free idealizers.
        Math. Proc. Cambridge Philos. Soc. 97 (1985), 7-26.   MR86a:16003
[21] (with Gert Almkvist and Edward Formanek)
        Hilbert series of fixed free algebras and noncommutative classical invariant theory.
        J. Algebra 93 (1985), 189-214.   MR86k:16001
   Erratum (March 15, 1999)
               Subscribers to ScienceDirect can download the article.
[20] (with W. Stephenson)
        Epimorphs and dominions of Dedekind domains.
        J. London Math. Soc. (2) 29 (1984), 224-228.   MR85i:16054
   An additional reference
                Subscribers to the Journal of the London Mathematical Society Online can download the article.
[19] Automorphisms of the polynomial ring in two variables.
        Publ. Sec. Mat. Univ. Autònoma Barcelona 27 (1983), 155-162.   MR86b:13004
[18] A free algebra can be free as a module over a nonfree subalgebra.
       Bull. London Math. Soc. 15 (1983), 373-377.   MR84j:16001
                Subscribers to the Bulletin of the London Mathematical Society Online can download the article.
[17] The HNN construction for rings.
        J. Algebra 81 (1983), 434-487.   MR85c:16005
               Subscribers to ScienceDirect can download the article.
[16] Free algebras over Bezout domains are Sylvester domains.
        J. Pure Appl. Algebra 27 (1983), 15-28.   MR84a:16003
               Subscribers to ScienceDirect can download the article.
[15] (with Edward Formanek)
       Poincaré series and a problem of S. Montgomery.
       Linear and Multilinear Algebra 12 (1982/83), 21-30.   MR84c:15032
                Subscribers to Taylor & Francis can download the article.
[14] (with Jacques Lewin)
       A Jacobian conjecture for free associative algebras.
       Comm. Algebra 10 (1982), 1285-1306.   MR83j:16046
                Subscribers to Taylor & Francis can download the article.
[13] A commutator test for two elements to generate the free algebra of rank two.
       Bull. London Math. Soc. 14 (1982), 48-51.   MR83g:16005
                Subscribers to the Bulletin of the London Mathematical Society Online can download the article.
[12] On splitting augmentation ideals.
        Proc. Amer. Math. Soc. 83 (1981), 221-227.   MR82k:16011
               Subscribers to JSTOR can download the article.
[11] An exact sequence for rings of polynomials in partly commuting indeterminates.
         J. Pure Appl. Algebra 22 (1981), 215-228.   MR82m:16024
               Subscribers to ScienceDirect can download the article.
[10*] Groups, trees and projective modules.
          Lecture Notes in Mathematics 790, Springer, Berlin, 1980. ix+127pp.   MR82j:20079 
   Errata and addenda (October 28, 2005)
                Subscribers to SpringerLink can download the book.
  [9] (with P. M. Cohn)
       On central extensions of skew fields.
        J. Algebra 63 (1980), 143-151.   MR82m:16014
               Subscribers to ScienceDirect can download the article.
  [8] Hereditary group rings.
        J. London Math. Soc.(2) 20 (1979), 27-38.   MR80k:16017
                Subscribers to the Journal of the London Mathematical Society Online can download the article.
  [7] (with Pere Menal)
        The group rings that are semifirs.
        J. London Math. Soc. (2) 19 (1979), 288-290.   MR80g:16002
                Subscribers to the Journal of the London Mathematical Society Online can download the article.
  [6] (with George M. Bergman)
       Universal derivations and universal ring constructions.
       Pacific J. Math. 79 (1978), 293-337.   MR81b:16024 
    Addenda (July 12, 2005)
  [5] (with Eduardo D. Sontag)
        Sylvester domains.
        J. Pure Appl. Algebra 13 (1978), 243-275.   MR80j:16014
   Errata (February 13, 2004)
               Subscribers to ScienceDirect can download the article.
  [4] Mayer-Vietoris presentations over colimits of rings.
        Proc. London Math. Soc. (3) 34 (1977), 557-576.   MR56#3059
                Subscribers to the Proceedings of the London Mathematical Society Online can download the article.
  [3] (with P. M. Cohn)
        Localization in semifirs. II
        J. London Math. Soc. (2) 13 (1976), 411-418.   MR54#12814
  Erratum (February 20, 2004)
                Subscribers to the Journal of the London Mathematical Society Online can download the article.
  [2] (with George M. Bergman)
       On universal derivations.
       J. Algebra 36 (1975), 193-211.   MR52#8196
               Subscribers to ScienceDirect can download the article.
  [1] On one-relator associative algebras.
        J. London Math. Soc. (2) 5 (1972), 249-252.   MR47#274
                Subscribers to the Journal of the London Mathematical Society Online can download the article.

Other publications

[1] Automorphisms of the free algebra of rank two.
     Group actions on rings (Brunswick, Maine, 1984), 63-68,
     Contemp. Math., 43, Amer. Math. Soc., Providence, R.I., 1985. MR86j:16007
[2] A survey of recent work on the cohomology of one-relator associative algebras.
      Ring theory (Granada, 1986), 75-81,
      Lecture Notes in Math., 1328, Springer, Berlin, 1988. MR89m:16049
                Subscribers to SpringerLink can download the article.
[3] (with Joaquim Bruna)
     Pere Menal i Brufal, 1951-1991.
     Publ. Mat. 36 (1992), 355-358. MR93m:01063
[4] (with Manuel Castellet and Jaume Moncasi, Eds.)
      Collected works of Pere Menal.
      Societat Catalana de Matemàtiques, Barcelona;
           distributed by Birkhäuser Verlag, Basel, 1994. xiv+639 pp. MR98e:01021
[5] (with Oriol Serra)
      The Dicks–Ivanov problem and the Hamidoune problem.
      European Journal of Combinatorics, (to appear).

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