The cophylogeny reconstruction problem arises in the study of host-parasite relationships. Specif- ically, we are given a host tree H, a parasite tree P, and a function \u27 mapping the leaves (extant taxa) of P to the leaves of H. Four biologically plausible operations are considered: cospeciation, duplication, host switching, and loss (Figure 1). A host switch is permitted in conjunction with a duplication event but not with a cospeciation event [1]
