The reticulation lower-bound conjecture for tree-metrizable minimal support networks

Let $N(B)$ be a tree-metrizable minimal support network of a biconnected component $B$, and suppose that $N(B)$ has $n$ leaves. A reticulation arc is an arc entering a reticulation vertex. Reticulation lower-bound conjecture. The network $N(B)$ has at least $n-2$ reticulation arcs. This conjecture would provide a quantitative constraint on tree-metrizable minimal support networks and could give deeper insight into the mathematical structures behind tree-metrizability. The source presents it as an unresolved conjecture and gives no known proof or disproof.