#### Volume 15, issue 4 (2011)

 1 Y Algom-Kfir, The Lipschitz metric on Outer Space, PhD thesis, University of Utah (2010) 2 Y Algom-Kfir, M Bestvina, Asymmetry of Outer Space, Geom. Dedicata (to appear) arXiv:0910.5408v1 3 J A Behrstock, Asymptotic geometry of the mapping class group and Teichmüller space, Geom. Topol. 10 (2006) 1523 MR2255505 4 M Bestvina, A bers–like proof of the existence of train tracks for free group automorphisms arXiv:1001.0325v2 5 M Bestvina, M Feighn, Outer limits, preprint (1994) 6 M Bestvina, M Feighn, The topology at infinity of $\mathrm{Out}(F_n)$, Invent. Math. 140 (2000) 651 MR1760754 7 M Bestvina, M Feighn, M Handel, Laminations, trees, and irreducible automorphisms of free groups, Geom. Funct. Anal. 7 (1997) 215 MR1445386 8 M Bestvina, M Feighn, M Handel, The Tits alternative for $\mathrm{Out}(F_n)$ I: Dynamics of exponentially-growing automorphisms, Ann. of Math. $(2)$ 151 (2000) 517 MR1765705 9 M Bestvina, K Fujiwara, A characterization of higher rank symmetric spaces via bounded cohomology, Geom. Funct. Anal. 19 (2009) 11 MR2507218 10 M Bestvina, M Handel, Train tracks and automorphisms of free groups, Ann. of Math. $(2)$ 135 (1992) 1 MR1147956 11 M R Bridson, A Haefliger, Metric spaces of non-positive curvature, Grundlehren der Mathematischen Wissenschaften 319, Springer (1999) MR1744486 12 Y E Choi, K Rafi, Comparison between Teichmüller and Lipschitz metrics, J. Lond. Math. Soc. $(2)$ 76 (2007) 739 MR2377122 13 M M Cohen, M Lustig, Very small group actions on $\mathbb{R}$–trees and Dehn twist automorphisms, Topology 34 (1995) 575 MR1341810 14 D Cooper, Automorphisms of free groups have finitely generated fixed point sets, J. Algebra 111 (1987) 453 MR916179 15 M Culler, J W Morgan, Group actions on $\mathbb{R}$–trees, Proc. London Math. Soc. $(3)$ 55 (1987) 571 MR907233 16 M Culler, K Vogtmann, Moduli of graphs and automorphisms of free groups, Invent. Math. 84 (1986) 91 MR830040 17 C Druţu, S Mozes, M Sapir, Divergence in lattices in semisimple Lie groups and graphs of groups, Trans. Amer. Math. Soc. 362 (2010) 2451 MR2584607 18 C Druţu, M Sapir, Tree-graded spaces and asymptotic cones of groups, Topology 44 (2005) 959 MR2153979 19 M Duchin, K Rafi, Divergence of geodesics in Teich\”muller space and the mapping class group arXiv:math/0611359 20 S Francaviglia, A Martino, Metric properties of Outer Space arXiv:0803.0640 21 D Gaboriau, A Jaeger, G Levitt, M Lustig, An index for counting fixed points of automorphisms of free groups, Duke Math. J. 93 (1998) 425 MR1626723 22 U Hamenstaedt, Lines of minima in Outer Space arXiv:0911.3620 23 M Handel, L Mosher, Axes in Outer Space arXiv:math/0605355 24 M Handel, L Mosher, Parageometric outer automorphisms of free groups, Trans. Amer. Math. Soc. 359 (2007) 3153 MR2299450 25 A Lenzhen, K Rafi, J Tao, Bounded combinatorics and the Lipschitz metric on Teichmüller space arXiv:1011.6078 26 G Levitt, M Lustig, Irreducible automorphisms of $F_n$ have north-south dynamics on compactified Outer Space, J. Inst. Math. Jussieu 2 (2003) 59 MR1955207 27 R Martin, Non-uniquely ergodic foliations of thin-type, measured currents and automorphisms of free groups, PhD thesis, University of California, Los Angeles (1995) MR2693216 28 H Masur, On a class of geodesics in Teichmüller space, Ann. of Math. $(2)$ 102 (1975) 205 MR0385173 29 H A Masur, M Wolf, Teichmüller space is not Gromov hyperbolic, Ann. Acad. Sci. Fenn. Ser. A I Math. 20 (1995) 259 MR1346811 30 Y N Minsky, Quasi-projections in Teichmüller space, J. Reine Angew. Math. 473 (1996) 121 MR1390685 31 F Paulin, The Gromov topology on $\mathbb{R}$–trees, Topology Appl. 32 (1989) 197 MR1007101 32 W Thurston, Minimal stretch maps between hyperbolic surfaces arXiv:math.GT/9801039 33 J H C Whitehead, On certain sets of elements in a free group, Proc. London Math. Soc. 41 (1936) 48