One point to define them all
A real-valued function f is defined on a set X. There exists an x from X such that IF f(x) = 0 THEN f is a constant 0.
What can we say about f and X in terms of necessary conditions?
Answer: Any function and any set satisfies the above property! And the function doesn’t have to be real-valued too. The statement was designed to confuse the reader.
In any set of cats C there exists a cat c such that IF c is black THEN all cats in C are black.