Computable bounds for Rasmussen's concordance invariant

Abstract

Given a diagram D of a knot K, we give easily computable bounds for Rasmussen's concordance invariant s(K). The bounds are not independent of the diagram D chosen, but we show that for diagrams satisfying a given condition the bounds are tight. As a corollary we improve on previously known Bennequin-type bounds on the slice genus. © Copyright Foundation Compositio Mathematica 2010.