2 problems

Let $M$ be a strictly upper triangular $(0,2)$-matrix, meaning that its entries are $0$ or $2$, and suppose that for each $k\geq 3$ there is at most one pair $(i,j)$ with $j-i=k$ a…

Let $n$ be a positive integer. A braid projection is a braid diagram without over/under-crossing information. Its CN matrix $N(B)$ is the zero-diagonal matrix whose $(i,j)$ entry c…