  Building on Peres's idea of "Delayed-choice for extanglement swapping" we
show that even the degree to which quantum systems were entangled can be
defined after they have been registered and may even not exist any more. This
does not arise as a paradox if the quantum state is viewed as just a
representative of information. Moreover such a view gives a natural
quantification of the complementarity between the measure of information about
the input state for teleportation and the amount of entanglement of the
resulting swapped entangled state.
