3 problems

Let $k$ be a real number with $0\leq k\leq 2$. For a natural number $n$, let $\lambda _1,\dots,\lambda _n$ be nonzero numbers satisfying … for all $i,j=1,\dots,n$. Positivity conje…

Undecidability conjecture. It is undecidable to check whether

Upper-bound conjecture. The number of such scalings was conjectured to be upper-bounded.