Fine projection complex and subsurface homeomorphisms with positive stable commutator length

Abstract

Drawing inspiration from [BBF15], we construct a family of unbounded quasi-trees for a connected closed oriented surface $S_g$ of genus $g\ge 2$, upon which the group ${\mathrm{Homeo}}_0(S_g)$ acts coboundedly by isometries. As an application, we show that some surface homeomorphisms preserving a non-sporadic essential subsurface or an essential subsurface homeomorphic to a once-bordered torus can have positive stable commutator length in ${\mathrm{Homeo}}_0(S_g)$. Moreover, we provide a version of projection complex that does not require the finiteness condition.

52 pages, 3 figures. Theorem 1.6 and Section 7 added