  The subject of this note is a challenging conjecture about X-rays of
permutations which is a special case of a conjecture regarding Skolem
sequences. In relation to this, Brualdi and Fritscher [Linear Algebra and its
Applications, 2014] posed the following problem: Determine a bijection between
extremal Skolem sets and binary Hankel X-rays of permutation matrices. We give
such a bijection, along with some related observations.
