70 citations · 480 across the 69 of their papers we have counts for
8 papers · 1 filter
The Euler class of planar groups
Danny Calegari
This is an exposition of the homological classification of actions of surface groups on the plane, in every degree of smoothness.
Large scale geometry of commutator subgroups
Danny Calegari, Dongping Zhuang
Let G be a finitely presented group, and G' its commutator subgroup. Let C be the Cayley graph of G' with all commutators in G as generators. Then C is large scale simply connected…
Faces of the scl norm ball
Danny Calegari
Let F be the fundamental group of S, where S is a compact, connected, oriented surface with negative Euler characteristic and nonempty boundary. (1) The projective class of the cha…
Combable functions, quasimorphisms, and the central limit theorem
Danny Calegari, Koji Fujiwara
A function on a discrete group is weakly combable if its discrete derivative with respect to a combing can be calculated by a finite state automaton. A weakly combable function is…
Surface subgroups from homology
Danny Calegari
Let G be a word-hyperbolic group, obtained as a graph of free groups amalgamated along cyclic subgroups. If H_2(G;Q) is nonzero, then G contains a closed hyperbolic surface subgrou…
Nonsmoothable, locally indicable group actions on the interval
Danny Calegari
By the Thurston stability theorem, a group of C^1 orientation-preserving diffeomorphisms of the closed unit interval is locally indicable. We show that the local order structure of…