  We show here that the recent work of Wolf and Wullschleger (quant-ph/0502030)
on oblivious transfer apparently opens the possibility that non-local
correlations which are stronger than those in quantum mechanics could be used
for bit-commitment. This is surprising, because it is the very existence of
non-local correlations which in quantum mechanics prevents bit-commitment. We
resolve this apparent paradox by stressing the difference between non-local
correlations and oblivious transfer, based on the time-ordering of their inputs
and outputs, which prevents bit-commitment.
