  It is well-known that entanglement of formation (EOF) and relative entropy of
entanglement (REE) are exactly identical for all two-qubit pure states even
though their definitions are completely different. We think this fact implies
that there is a veiled connection between EOF and REE. In this context, we
suggest a procedure, which enables us to compute REE from EOF without relying
on the converse procedure. It is shown that the procedure yields correct REE
for many symmetric mixed states such as Bell-diagonal, generalized
Vedral-Plenino, and generalized Horodecki states. It also gives a correct REE
for less symmetric Vedral-Plenio-type state. However, it is shown that the
procedure does not provide correct REE for arbitrary mixed states.
