My friend used the statement:
"My examination date is postponed."
I think the event can be postponed, not a date.
So, his statement should be "My examination is postponed."
However, when I checked the word "postpone date" and "date is postponed" on Google NGram, I found that this combination is used a lot. So, is it a valid way of using the word "postpone"?
Logically speaking it is impossible to postpone a date since it cannot be moved in time. You cannot postpone time in time either. An event on the other hand can be postponed to happen some other time, either earlier or later.
I'd say that from the point of view of logic his statement is wrong, but it can clearly be understood by listerners who will eventually render it as "The examination was postponed to a different date" or "The date of my examination changed".
Saying that an event is postponed is simple and clear, which makes it a tautology to say that the date of an event is postponed.
