Problems / combinatorics
combinatorics / Mathematical phylogenetics; circular split systems
All-level NANUQ circularity and exact displayed-split support
Original NANUQ is circular decomposable at every finite level and with any number of blobs in the binary semi-directed LSA, galled, outer-labeled planar class (at least four taxa). Its positive split support equals the union of displayed-tree splits. This answers the source's level-two multi-blob and level-three circularity questions. A six-label reduction, exact finite certificate and composition identity remove the level bound. The local four-score family has exact universal anchor-positivity domain s=o=1, 1/2<=a<=1, 0<=c<=a; five labels are the sharp testing cutoff. Contiguous multicopy trees admit an extreme-copy reduction. Raw-matrix error <1/2 is optimally correctable by rounding; exact support uses a supplied correct order. Planarity cannot be dropped for exact support. Full all-level Lean verification, network uniqueness, statistical inference and unrestricted ARGs are not claimed.