Cook’s Theorem
CNF-satisfiability is NP-complete
Proof formalizes the notion of a nondeterministic algorithm
as a nondeterministic Turing machine. Cook then shows
that a CNF-formula F can be produced in polynomial time
that describes the operation of the nondeterministic
Turning machine. The Turing machine halts in a “yes”
state if and only if the formula F is satisfiable.