 Bearing in mind what we said above about the interconnectedness of character analysis and phylogenetic analysis, we will now proceed to the second part, analysis of the data. At this stage, computational limits loom large. Even if we are concerned only with inferring the topology of a phylogeny, the number of possible trees grows exponentially relative to the number of terminal branches we include on a tree. The formula for calculating the number of possible tree topologies is relatively straight-forward (Felsenstein 2004):