We study a notion of distance between knots, defined in terms of the number of saddles in ribbon concordances connecting the knots. We construct a lower bound on this distance using the –action on Lee’s perturbation of Khovanov homology.
"Ribbon distance and Khovanov homology." Algebr. Geom. Topol. 20 (2) 1041 - 1058, 2020. https://doi.org/10.2140/agt.2020.20.1041