Well-Characterized also known as
Good-Characterized is defined as follows:
Problem that have Yes and No certificates i.e., are in NP $\cap$ co-NP, are said to be Well-Characterized. (Reference: V.Vazirani, Approximation Algorithm)
Does exist any
Well-Chracterized problem that is also being
NP-Complete? I don't looking for any proof, I just want a real-world example of such problem.