On the TTSC-FTSC Formulation of Standard Parsimony

Standard parsimony analysis has recently been described in a "three-taxon-like" way (the three-taxa statements for contiguous series-four-taxa statements for contiguous series, or TTSC-FTSC procedure) in order to clarify the differences between the standard approach and three-taxon analysis. It is shown that the alleged equivalence of standard parsimony analysis and the TTSC-FTSC procedure does not hold. Some minor defects of the procedure can be fixed within the TTSC-FTSC logic, but no solution is available for two basic problems: (1) the elementary three-taxon-like statements of the TTSC-FTSC procedure are highly artificial; and (2) the equivalence with standard parsimony depends on an incomplete correction for nonindependence between these statements. However, these findings do not invalidate the reported superiority of standard parsimony as a method for biological systematics.