Braid commutators and delta finite-type invariants
arXiv:math/9907071
Abstract
Delta finite-type invariants are defined analogously to finite-type invariants, using delta moves instead of crossing changes. We show that they are closely related to the lower central series of the commutator subgroup of the pure braid group.
6 pages, 2 figures, based on talk given in Delphi, August 1998