2 problems

For a finite point configuration $P\subset\mathbb{R}^d$ and an integer $k\geq 0$, let $[P]_k$ be the set of point configurations $Q\in(\mathbb{R}^d)^X$ such that every chirotope of…

McMullen–Shephard conjecture. Every projectively unique $4$-polytope is accounted for in Shephard's list of $11$ combinatorial types of projectively unique $4$-polytopes.