An approximation algorithm for bounded degree closest phylogenetic 2nd root problem

The degree Δ-closest phylogenetic 2nd root problem (ΔCPR
₂
) is an NP-hard problem concerning phylogenetic tree reconstruction from a graph representing the similarities of the species concerned. Here we present an approximation algorithm for this problem for any fixed Δ >; 3. When |V| >; 3Δ - 1, our algorithm yields an approximation ratio of max((Δ-2)/α, 2), where α >; 1 is a constant whose value depends on the values of |V| and Δ.