L. Lamata et al. have presented an entanglement classification of four qubits
under stochastic local operation and classical communication (SLOCC) based on
inductive approach [Phys. Rev. A \textbf{75}, 022318 (2007)]. While it works
well for three qubits, we show that some of the families for four qubits have
overlaps and hence this approach is not valid for entanglement classification
of four or more qubits under SLOCC
