2 problems

For each $n\ge 11$, let $\mathcal{G}_n$ be the quartic graph of order $n$ constructed from the blocks displayed in the paper, and call a quartic graph minimal when it has minimum s…

Quartic minimum-gap conjecture. The connected quartic graph on $n\geq 11$ vertices with minimum spectral gap is the unique graph $G$ described as follows: $G$ consists of $q$ middl…