original_query: What is the definition of perfect phylogeny in computational phylogenetics?
query: What is the definition of perfect phylogeny in computational phylogenetics?
answer: In computational phylogenetics, perfect phylogeny is a phylogenetic tree where all internal nodes can be labeled so that all characteristics evolve down the tree without homoplasy (evolutionary convergence or analogous structures).  Essentially, each characteristic changes from absent (0) to present (1) exactly once and never reverts.