  The entanglement of formation as well as the conditional entropy can be used
to define leaves in the state space, given by a linear superposition of their
extremal points. Examples are presented, where these leaves can be specified
and can be used to calculate the entanglement respectively the conditional
entropy. The definition of entanglement is generalized to infinite systems and
allows again to define a leaf structure. Finally we remark on the additivity
property of both expressions, offering a counter example to the additivity of
the conditional entropy.
