Special alternating knots are ribbon concordance minimal

Let $K$ and $K'$ be knots in $S^3$, and write $K'\leq K$ when there is a ribbon concordance from $K$ to $K'$. A knot $K$ is ribbon concordance minimal if $K'\leq K$ implies that $K'$ is equivalent to $K$. Special alternating knot minimality conjecture. Every special alternating knot is ribbon concordance minimal. The paper verifies this in several cases, including fibered knots, knots whose Alexander polynomial has prime-power leading coefficient, and two-bridge knots, but the general conjecture remains open.