Complexity column

Computational Complexity Questions, such as trying to prove that the NP-complete problem three colorability of graphs (3COLOR) cannot be checked in polynomial time, seemed deceptively simple when I first encountered them as a grad student in the 1970's. So many years later, we still don't even know whether 3COLOR is in the uniform circuit class ACC06, or equivalently, whether it is expressible in first-order logic with sum mod 6 quantifiers and numeric relations +, *.