A simple fixed parameter tractable algorithm for computing the   hybridization number of two (not necessarily binary) trees
  Here we present a new fixed parameter tractable algorithm to compute the hybridization number r of two rooted, not necessarily binary phylogenetic trees on taxon set X in time (6^r.r!).poly(n)$, where n=|X|. The novelty of this approach is its use of terminals, which are maximal elements of a natural partial order on X, and several insights from the softwired clusters literature. This yields a surprisingly simple and practical bounded-search algorithm and offers an alternative perspective on the underlying combinatorial structure of the hybridization number problem. 
Teresa Piovesan and Steven Kelk
q-bio.QM math.CO q-bio.PE