2 problems

A graph $G$ is harmonious when it admits a harmonious labeling, namely an injective vertex labeling whose induced edge labels are also injective modulo $|E(G)|$; for trees, the def…

Let $T$ be a tree with $n$ vertices. A harmonious labelling assigns distinct vertex labels and gives an edge $uv$ the label $(\psi(u)+\psi(v))\bmod(n-1)$. Harmonious Tree Conjectur…