When is region crossing change an unknotting operation?
arXiv:1201.1735 · doi:10.1017/S0305004113000236
Abstract
In this paper, we prove that region crossing change on a link diagram is an unknotting operation if and only if the link is proper. A description of the behavior of region crossing change on link diagrams is given. Furthermore we also discuss the relation between region crossing change and the Arf invariant of proper links.
10 pages, 7 figures