We evaluate the one-shot entanglement of assistance for an arbitrary
bipartite state. This yields another interesting result, namely a
characterization of the one-shot distillable entanglement of a bipartite pure
state. This result is shown to be stronger than that obtained by specializing
the one-shot hashing bound to pure states. Finally, we show how the one-shot
result yields the operational interpretation of the asymptotic entanglement of
assistance proved in [Smolin et al., Phys. Rev. A 72, 052317 (2005)].Comment: 23 pages, one column, final published versio