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Bestvina, Feighn and Handel later proved that the group Out(''F<sub>n</sub>'') satisfies the [[Tits alternative]],<ref name="BFH00">Mladen Bestvina, Mark Feighn, and Michael Handel. [http://www.emis.ams.org/journals/Annals/151_2/bestvina.pdf ''The Tits alternative for Out(F<sub>n</sub>). I. Dynamics of exponentially-growing automorphisms.''] [[Annals of Mathematics]] (2), vol. 151 (2000), no. 2, pp. 517&ndash;623</ref><ref name="BFH05">Mladen Bestvina, Mark Feighn, and Michael Handel. [http://annals.princeton.edu/annals/2005/161-1/p01.xhtml ''The Tits alternative for Out(F<sub>n</sub>). II. A Kolchin type theorem.''] [[Annals of Mathematics]] (2), vol. 161 (2005), no. 1, pp. 1&ndash;59</ref> settling a long-standing open problem.
Bestvina, Feighn and Handel later proved that the group Out(''F<sub>n</sub>'') satisfies the [[Tits alternative]],<ref name="BFH00">Mladen Bestvina, Mark Feighn, and Michael Handel. [http://www.emis.ams.org/journals/Annals/151_2/bestvina.pdf ''The Tits alternative for Out(F<sub>n</sub>). I. Dynamics of exponentially-growing automorphisms.''] [[Annals of Mathematics]] (2), vol. 151 (2000), no. 2, pp. 517&ndash;623</ref><ref name="BFH05">Mladen Bestvina, Mark Feighn, and Michael Handel. [http://annals.princeton.edu/annals/2005/161-1/p01.xhtml ''The Tits alternative for Out(F<sub>n</sub>). II. A Kolchin type theorem.''] [[Annals of Mathematics]] (2), vol. 161 (2005), no. 1, pp. 1&ndash;59</ref> settling a long-standing open problem.


In a 1997 paper<ref>Bestvina, Mladen and Brady, Noel, ''Morse theory and finiteness properties of groups''. [[Inventiones Mathematicae]], vol. 129 (1997), no. 3, pp. 445&ndash;470</ref> Bestvina and Brady developed a version of discrete [[Morse theory]] for cubical complexes and applied it to study homological finiteness properties of subgroups of right-angled [[Artin group]]s. In particular, they constructed an example of a group which provides a counter-example to either the [[Whitehead conjecture|Whitehead asphericity conjecture]] or to the [[Eilenberg−Ganea conjecture]], thus showing that at least one of these conjectures must be false. Brady subsequently used their Morse theory technique to construct the first example of a [[finitely presented group|finitely presented]] subgroup of a [[word-hyperbolic group]] that is not itself word-hyperbolic.<ref>Brady, Noel, ''Branched coverings of cubical complexes and subgroups of hyperbolic groups''. [[Journal of the London Mathematical Society]] (2), vol. 60 (1999), no. 2, pp. 461&ndash;480</ref>
In a 1997 paper<ref>Bestvina, Mladen and Brady, Noel, ''Morse theory and finiteness properties of groups''. [[Inventiones Mathematicae]], vol. 129 (1997), no. 3, pp. 445&ndash;470</ref> Bestvina and Brady developed a version of [[discrete Morse theory]] for cubical complexes and applied it to study homological finiteness properties of subgroups of right-angled [[Artin group]]s. In particular, they constructed an example of a group which provides a counter-example to either the [[Whitehead conjecture|Whitehead asphericity conjecture]] or to the [[Eilenberg−Ganea conjecture]], thus showing that at least one of these conjectures must be false. Brady subsequently used their Morse theory technique to construct the first example of a [[finitely presented group|finitely presented]] subgroup of a [[word-hyperbolic group]] that is not itself word-hyperbolic.<ref>Brady, Noel, ''Branched coverings of cubical complexes and subgroups of hyperbolic groups''. [[Journal of the London Mathematical Society]] (2), vol. 60 (1999), no. 2, pp. 461&ndash;480</ref>


==Selected publications==
==Selected publications==

Revision as of 12:57, 24 October 2011

Mladen Bestvina is a Croatian American mathematician working in the area of geometric group theory. He is a Distinguished Professor in the Department of Mathematics at the University of Utah.

Biographical info

Mladen Bestvina is a three-time medalist at the International Mathematical Olympiad (two silver medals in 1976 and 1978 and a bronze medal in 1977).[1] He received a B. Sc. in 1982 from the University of Zagreb.[2] He obtained a PhD in Mathematics in 1984 at the University of Tennessee under the direction of John Walsh.[3] Bestvina had been a faculty member at UCLA, and joined the faculty in the Department of Mathematics at the University of Utah in 1993.[4] He was appointed a Distinguished Professor at the University of Utah in 2008.[4] Bestvina received the Alfred P. Sloan Fellowship in 1988–89[5][6] and a Presidential Young Investigator Award in 1988–91.[7]

Bestvina gave an Invited Address at the International Congress of Mathematicians in Beijing in 2002.[8] He also gave a Unni Namboodiri Lecture in Geometry and Topology at the University of Chicago.[9]

Bestvina served as an Editorial Board member for the Transactions of the American Mathematical Society.[10] He is currently an associate editor of the Annals of Mathematics[11] and an Editorial Board member for Geometric and Functional Analysis,[12] the Journal of Topology and Analysis,[13] Groups, Geometry and Dynamics,[14] Michigan Mathematical Journal,[15] Rocky Mountain Journal of Mathematics,[16] and Glasnik Matematicki.[17]

Mathematical contributions

A 1988 monograph of Bestvina[18] gave an abstract topological characterization of universal Menger compacta in all dimensions; previously only the cases of dimension 0 and 1 were well understood. John Walsh wrote in a review of Bestvina's monograph:This work, which formed the author's Ph.D. thesis at the University of Tennessee, represents a monumental step forward, having moved the status of the topological structure of higher-dimensional Menger compacta from one of ``close to total ignorance" to one of ``complete understanding".[19]

In a 1992 paper Bestvina and Feighn obtained a Combination Theorem for word-hyperbolic groups.[20] The theorem provides a set of sufficient conditions for amalgamated free products and HNN extensions of word-hyperbolic groups to again be word-hyperbolic. The Bestvina–Feighn Combination Theorem became a standard tool in geometric group theory and has had many applications and generalizations (e.g.[21][22][23][24] ).

Bestvina and Feighn also gave the first published treatment of Rips' theory of stable group actions on R-trees (the Rips machine)[25] In particular their paper gives a proof of the Morgan–Shalen conjecture[26] that a finitely generated group G admits a free isometric action on an R-tree if and only if G is a free product of surface groups, free groups and free abelian groups.

A 1992 paper of Bestvina and Handel introduced the notion of a train track map for representing elements of Out(Fn).[27] In the same paper they introduced the notion of a relative train track and applied train track methods to solve[27] the Scott conjecture which says that for every automorphism α of a finitely generated free group Fn the fixed subgroup of α is free of rank at most n. Since then train tracks became a standard tool in the study of algebraic, geometric and dynamical properties of automorphisms of free groups and of subgroups of Out(Fn). Examples of applications of train tracks include: a theorem of Brinkmann[28] proving that for an automorphism α of Fn the mapping torus group of α is word-hyperbolic if and only if α has no periodic conjugacy classes; a theorem of Bridson and Groves[29] that for every automorphism α of Fn the mapping torus group of α satisfies a quadratic isoperimetric inequality; a proof of algorithmic solvability of the conjugacy problem for free-by-cyclic groups;[30] and others.

Bestvina, Feighn and Handel later proved that the group Out(Fn) satisfies the Tits alternative,[31][32] settling a long-standing open problem.

In a 1997 paper[33] Bestvina and Brady developed a version of discrete Morse theory for cubical complexes and applied it to study homological finiteness properties of subgroups of right-angled Artin groups. In particular, they constructed an example of a group which provides a counter-example to either the Whitehead asphericity conjecture or to the Eilenberg−Ganea conjecture, thus showing that at least one of these conjectures must be false. Brady subsequently used their Morse theory technique to construct the first example of a finitely presented subgroup of a word-hyperbolic group that is not itself word-hyperbolic.[34]

Selected publications

See also

References

  1. ^ "Mladen Bestvina". imo-official.org. International Mathematical Olympiad. Retrieved 2010-02-10.
  2. ^ Research brochure: Mladen Bestvina, Department of Mathematics, University of Utah. Accessed February 8, 2010
  3. ^ Mladen F. Bestvina, Mathematics Genealogy Project. Accessed February 8, 2010.
  4. ^ a b Mladen Bestvina: Distinguished Professor, Aftermath, vol. 8, no. 4, April 2008. Department of Mathematics, University of Utah.
  5. ^ Sloan Fellows. Department of Mathematics, University of Utah. Accessed February 8, 2010
  6. ^ Sloan Research Fellowships, Alfred P. Sloan Foundation. Accessed February 8, 2010
  7. ^ Award Abstract #8857452. Mathematical Sciences: Presidential Young Investigator. National Science Foundation. Accessed February 8, 2010
  8. ^ Invited Speakers for ICM2002. Notices of the American Mathematical Society, vol. 48, no. 11, December 2001; pp. 1343 1345
  9. ^ Annual Lecture Series. Department of Mathematics, University of Chicago. Accessed February 9, 2010
  10. ^ Officers and Committee Members, Notices of the American Mathematical Society, vol. 54, no. 9, October 2007, pp. 1178 1187
  11. ^ Editorial Board, Annals of Mathematics. Accessed February 8, 2010
  12. ^ Editorial Board, Geometric and Functional Analysis. Accessed February 8, 2010
  13. ^ Editorial Board. Journal of Topology and Analysis. Accessed February 8, 2010
  14. ^ Editorial Board, Groups, Geometry and Dynamics. Accessed February 8, 2010
  15. ^ Editorial Board, Michigan Mathematical Journal. Accessed February 8, 2010
  16. ^ Editorial Board, ROCKY MOUNTAIN JOURNAL OF MATHEMATICS. Accessed February 8, 2010
  17. ^ Editorial Board, Glasnik Matematicki. Accessed February 8, 2010
  18. ^ Bestvina, Mladen, Characterizing k-dimensional universal Menger compacta. Memoirs of the American Mathematical Society, vol. 71 (1988), no. 380
  19. ^ John J. Walsh, Review of: Bestvina, Mladen, Characterizing k-dimensional universal Menger compacta. Mathematical Reviews, MR0920964 (89g:54083), 1989
  20. ^ M. Bestvina and M. Feighn, A combination theorem for negatively curved groups. Journal of Differential Geometry, Volume 35 (1992), pp. 85–101
  21. ^ EMINA ALIBEGOVIC, A COMBINATION THEOREM FOR RELATIVELY HYPERBOLIC GROUPS. Bulletin of the London Mathematical Society vol. 37 (2005), pp. 459–466
  22. ^ Francois Dahmani, Combination of convergence groups. Geometry and Topology, Volume 7 (2003), 933–963
  23. ^ I. Kapovich, The combination theorem and quasiconvexity. International Journal of Algebra and Computation, Volume: 11 (2001), no. 2, pp. 185–216
  24. ^ M. Mitra, Cannon–Thurston maps for trees of hyperbolic metric spaces. Journal of Differential Geometry, Volume 48 (1998), Number 1, 135–164
  25. ^ M. Bestvina and M. Feighn. Stable actions of groups on real trees. Inventiones Mathematicae, vol. 121 (1995), no. 2, pp. 287 321
  26. ^ Morgan, John W., Shalen, Peter B., Free actions of surface groups on R-trees. Topology, vol. 30 (1991), no. 2, pp. 143–154
  27. ^ a b Mladen Bestvina, and Michael Handel, Train tracks and automorphisms of free groups. Annals of Mathematics (2), vol. 135 (1992), no. 1, pp. 1–51
  28. ^ P. Brinkmann, Hyperbolic automorphisms of free groups. Geometric and Functional Analysis, vol. 10 (2000), no. 5, pp. 1071–1089
  29. ^ Martin R. Bridson and Daniel Groves. The quadratic isoperimetric inequality for mapping tori of free-group automorphisms. Memoirs of the American Mathematical Society, to appear.
  30. ^ O. Bogopolski, A. Martino, O. Maslakova, E. Ventura, The conjugacy problem is solvable in free-by-cyclic groups. Bulletin of the London Mathematical Society, vol. 38 (2006), no. 5, pp. 787–794
  31. ^ Mladen Bestvina, Mark Feighn, and Michael Handel. The Tits alternative for Out(Fn). I. Dynamics of exponentially-growing automorphisms. Annals of Mathematics (2), vol. 151 (2000), no. 2, pp. 517–623
  32. ^ Mladen Bestvina, Mark Feighn, and Michael Handel. The Tits alternative for Out(Fn). II. A Kolchin type theorem. Annals of Mathematics (2), vol. 161 (2005), no. 1, pp. 1–59
  33. ^ Bestvina, Mladen and Brady, Noel, Morse theory and finiteness properties of groups. Inventiones Mathematicae, vol. 129 (1997), no. 3, pp. 445–470
  34. ^ Brady, Noel, Branched coverings of cubical complexes and subgroups of hyperbolic groups. Journal of the London Mathematical Society (2), vol. 60 (1999), no. 2, pp. 461–480

External links

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