2 problems

Let $\mathcal{C}$ be the classical knot concordance group. An element of $\mathcal{C}$ is 2-torsion if it has order two, and a knot is negative amphichiral if it is isotopic to its…

A knot is strongly positive amphichiral if it is equivalent to its mirror image by an orientation-preserving involution reversing the knot orientation, and a Lissajous knot admits…