Resumen de Ribbon concordance of surface-knots via quandle cocycle invariants

J. Scott Carter, Masahico Saito, Shin Satoh

• We give necessary conditions of a surface-knot to be ribbon concordant to another, by introducing a new variant of the cocycle invariant of surface-knots in addition to using the invariant already known. We demonstrate that twist-spins of some torus knots are not ribbon concordant to their orientation reversed images.