2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/70102We use Lee's work on the Khovanov homology to define a knot invariant s. We show that s(K) is a concordance invariant and that it provides a lower bound for the slice genus of K. As a corollary, we give a purely combinatorial proof of the Milnor conjecture.20 pages, 8 figuresGeometric TopologyQuantum Algebra57M27; 57R56text