0 votes 0 votes Prove or disprove that if $m$ and $n$ are integers such that $mn=1$, then either $m=1$ and $n=1$, or else $m=−1$ and $n=−1$. Mathematical Logic kenneth-rosen discrete-mathematics mathematical-logic propositional-logic + – Pooja Khatri asked Apr 4, 2019 Pooja Khatri 202 views answer comment Share Follow See all 0 reply Please log in or register to add a comment.