On the commutator length of a Dehn twist
arXiv:1007.0132 · doi:10.1016/j.crma.2010.07.011
Abstract
We show that on a nonorientable surface of genus at least 7 any power of a Dehn twist is equal to a single commutator in the mapping class group and the same is true, under additional assumptions, for the twist subgroup, and also for the extended mapping class group of an orientable surface of genus at least 3.
Two references and one paragraph added acknowledging the fact that some results were known already. 6 pages