3 papers
math.CO2026
An Explicit Threshold for Attaining the Semple--Steel Bound with -State Characters
Peng Li, Yangjing Long
Let be the maximum, over all binary phylogenetic trees with leaves, of the minimum number of -state characters required to define the tree. Semple and Steel proved…
math.CO2026
Exact Leaf Powers on Cycles, Ladders, Crowns, and Multipartite Block Graphs
Peng Li, Yangjing Long
Exact \(k\)-leaf powers are graphs whose edges are exactly the pairs of leaves at distance \(k\) in a tree. We prove explicit structure theorems for exact leaf powers on several re…
q-bio.PE2026
Computing the Arc-Deletion Distance to Orchard Networks is NP-hard
Peng Li, Zhiwei Liu, Yangjing Long
Phylogenetic networks generalize phylogenetic trees by allowing reticulate evolutionary events such as horizontal gene transfer and hybridization. Among the many subclasses of phyl…