Portable Message-Passing: Phylogenetic Trees.

p4 was used to develop a parallel version of the ``maximum likelihood'' method of computing phylogenetic trees from RNA sequence data [23]. The largest such tree ever computed was derived using p4 and the Intel Touchstone Delta. The portability of the program enabled it to be developed on a Sequent (which has a good debugging environment), run on small data sets on workstation networks, tested further on the Intel iPSC/860, and finally run in production mode on the Intel Delta, all without changing a single line of source code. Most recently, the same code has been used to discover new phylogenetic trees on the IBM SP-1.