The conjugacy problem for Dehn twist automorphisms of free groups

A Dehn twist automorphism of a group G is an automorphism which can be give n (as specified below) in terms of a graph-of-groups decomposition of G wit h infinite cyclic edge groups. The classic example is that of an automorphi sm of the fundamental group of a surface which is induced by a Dehn twist h omeomorphism of the surface. For G = F-n, a non-abelian free group of finit e rank n, a normal form for Dehn twist is developed, and it is shown that t his can be used to solve the conjugacy problem for Dehn twist automorphisms of F-n.