3 problems

Covering-array nonexistence conjecture. A $CA(12,8,3)$ does not exist; consequently, …

For integers $n$ and $k$, let $g(n,k)$ be the minimum covering multiplicity for a perfect sequence covering array with parameters $(n,k)$. The previously known exceptional values i…

A covering array $\operatorname{CA}(N,k,v)$ is an array with $N$ rows, $k$ columns, and entries from an alphabet of size $v$, such that every choice of two columns contains every o…