Areal-valued function f is defined to be continuous at the point x0if, and only if,
∀x∀ℇ≻0 ∃≻(|x-x0| ≺→|f(x) – f(x0)| ≺ℇ)
write the definition of a function not being continuous at the point x0, i. e., negate the
above proposition.