The paper proposes a logical model of combinatorial problems; it also
gives an example of a problem of the class NP that cannot be solved in
polynomial time on the dimension of the problem.
Crescenzi, P. and Kann,V. (1997) Approximation on the Web: A Compendium
of NP Optimization Problems. Proceedings of International Workshop RANDOM’97, Bologna,
11-12 July 1997,
111-118.
