2 problems

Let $d\ge2$ be an integer and let $R$ be a non-empty family of partitions on $\lbrack d\rbrack$. For an order-$d$ tensor $T$, let $\operatorname{d\mathit{R}rk}T$ denote its disjoin…

A representable matroid is a matroid satisfying the rank axioms of a matroid and representable over a field. Mayhew–Newman–Whittle conjecture. It is impossible to characterise the…