2 problems

Duality conjecture. A convex hyperbolic c-polyhedron has a convex hyperbolic dual if and only if it has an orientation of its vertex-disks so that all inversive distances are in…

Let $P$ be a harmonic $N$-gon, let $Q$ be a point, and let $P'$ be the $N$-gon obtained by inverting the vertices of $P$ in a circle centered at $Q$. Let $\mathcal{S}$ be the Schou…