2019/01/28 by Raty, Eero · 1 citation
#Combinatorics (math.CO) #FOS: Mathematics
paper · doi:10.48550/arxiv.1901.09814
For a family A⊆\ 0,…,k\ n, define the δ-shadow of A to be the set obtained from A by removing from any of its vectors one coordinate that equals zero. Given the size of A, how should we choose A to minimise its δ-shadow? Our aim in this paper is to show that, for any r, the family of all sequences with at most r zeros has minimal δ-shadow. We actually give the exact best A for every size.