at time now, (that unique object that is president of the united states is the same as that unique object that is Barak Obama.)
But I see that treating space and time equivelently, time is not an predicate on the assertion, but should be distributed, so one could say:
that unique object that was president of the unitied states at time June 1962 is the same as that unique object that at time June 1945 was the captain of PT109.
MW: In 4D you would say that slightly differently, since JFK is him for the whole of his life and you are talking about different temporal parts of him here. So I would say JFK has a temporal part (or state) that is captain of PT109 in June 1945 and another temporal part (state) that was President of the United States in 1962. Note that there are 3 objects (the whole life and the two states) because they have different spatio-temporal extents (they are not coincident over all space and time).
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