**Stephen A. Cook**, a noted computer scientist.

Cook formalised the notion of NP-completeness in a famous 1971 paper "The Complexity of Theorem Proving Procedures", which also contained a proof that the boolean satisfiability problem was NP-complete. The paper left open theoretical computer science's greatest unsolved question - whether complexity classes P and NP are equivalent, the answer to which has eluded researchers since.

Cook received the Turing Award in 1982 for his discovery. His citation reads:

*For his advancement of our understanding of the complexity of computation in a significant and profound way. His seminal paper, *The Complexity of Theorem Proving Procedures,* presented at the 1971 ACM SIGACT Symposium on the Theory of Computing, Laid the foundations for the theory of NP-Completeness. The ensuing exploration of the boundaries and nature of NP-complete class of problems has been one of the most active and important research activities in computer science for the last decade.*

He received his Bachelor's degree in 1961 from the University of Michigan. At Harvard University, he received his Master's degree in 1962 and his Ph.D in 1966.

Stephen Cook is currently a professor in the Mathematics Department at the University of Toronto.