  A recent paper claimed to give an entanglement measure for composite systems,
including Bose condensation and superconductivity. It is not an entanglement
measure. It does not distinguish entanglement and non-factorization merely due
to (anti)symmetrization for identical particles. In fact, the nature of
entanglement, beyond the effect of (anti)symmetrization, in important states of
many identical particles such as Bose condensation and superconductivity, had
already been studied earlier.
