2 problems

Let $G$ be a simple graph, let $v\in V(G)$, and let $G-v$ denote the graph obtained by deleting $v$. Twin-pair conjecture. If … then $G$ has at least one pair of twin vertices. Thi…

Let $G$ be a simple graph, let $delta":[0,1,-1]^{V(G)}$ be a vector, and let $\mathcal{T}_{\delta}(G)$ denote the associated family of graphs. A graph is minimal $k$-forbidden if i…