> "If X is greater than 10, X is greater than 20" theorems
I think you meant in the opposite order, i.e.: "If X is greater than 20, then X is greater than 10" :)
But otherwise your point is valid.
I think you meant in the opposite order, i.e.: "If X is greater than 20, then X is greater than 10" :)
But otherwise your point is valid.
I think I have seen theorems of that sort. (Can't think of a specific example right now.)
You could only prove it if you add something else, e.g. a precondition saying that X = 30.