The smallest sets of points not determined by their X-rays

Andreas Alpers, David G. Larman

Let $F$ be an $n$-point set in ${\mathbb{K}}^d$ with $\mathbb{K}\in \{\mathbb{R},\mathbb{Z}\}$ and $d\ge 2$. A (discrete) X-ray of $F$ in direction $s$ gives the number of points of…