2 problems

BFZ conjecture. Every acyclic sign-skew-symmetric matrix is totally sign-skew-symmetric.

Let $B$ be a sign-skew-symmetric matrix, meaning that for every $i,j$, either $b_{ij}=b_{ji}=0$ or $b_{ij}b_{ji}<0$. A matrix is totally sign-skew-symmetric if every matrix obtaine…