Many papers were written, circulated, but never published. The aim
of this page is to collect them and make them available. Feel free
to suggest additions!
Whenever possible I indicate the date, as well as published papers
where the main results are proved.
Warning: These papers are interesting, but haven't been properly
refereed, so beware...
Martin Lustig (+ Gautero and Los)
A tout seigneur tout honneur, we start with the conjugacy problem in
Out(F_n). Martin Lustig's 1994 announcement,
which was distributed during a conference in Luminy, and the Max
Planck preprints 12 (ps files).
Again by Martin, a 2004 paper
with Jerome Los. They show contractibility of the set of efficient
representatives of an irreducible automorphism of F_n, and they
introduce a canonical folding in outer space (different from
And a 2007 paper with
François Gautero. They show that the mapping torus of an
automorphism of F_n is hyperbolic relative to mapping tori of
polynomial subgroups (these subgroups are defined in my 2009 paper on growth).
Anything else, Martin?
I mentioned Skora, I know two unpublished papers by him, both from
one studies free products with amalgamation and HNN extensions of
actions on R-trees.
one is better known: he shows contractibility of outer space by
defining a folding process. See Matt Clay's paper, and my paper with Vincent
limits paper (1992, revised 1994). See my 1995 paper with
Damien Gaboriau about the rank of actions for the dimension of
compactified outer space, and Camille Horbez's recent paper for the fact that
all very small trees belong to the boundary of outer space. I don't
know a reference for Bestvina-Feighn's free group decomposition
lemma (Lemma 4.1).
Arnaud wrote his thesis in 2004 on the action of a given
automorphism of F_n on the union of F_n and its boundary. Most
results are only available there
His second Nielsen-Thurston paper
(1995). He constructs a hierarchical decomposition for automorphisms
of F_n by studying periodic free factors.
Even Vincent has an unpublished paper
(2001). Bestvina-Feighn gave a bound for the complexity of
simplicial trees with small edge stabilizers. Vincent gives a bound
about the boundary of the curve complex (1999).
In his thesis (1999) Shor proved that a torsion free hyperbolic
group contains, up to isomorphism, only finitely many fixed
subgroups of automorphisms. Paper
There is a proof in a paper
I wrote with Martin Lustig (see also
His 1995 thesis
(ps file) constructs thin (exotic) measured foliations which are not
uniquely ergodic, and discusses currents in free groups.
His 2001 thesis Algorithmic
Properties of Relatively Hyperbolic Groups, showing that
certain groups are biautomatic.
My contribution: I proved in
the isomorphism problem is unsolvable for [free abelian]-by-free
groups. But Bruno Zimmermann had published a similar result in 1985
(reference 13 in publications).
His paper was in German, though. Reference 8 is another paper which
is not sufficiently known: he showed (in 1981) that any finite
subgroup of Out(F_n) may be realized as symmetries of a graph.
Martin Bridson and Andy Miller
There seems to be a lost 1991 paper showing that "any finite
subgroup fixes a point in McCullough-Miller space". Does anyone have