Title: The complexity of natural extensions of efficiently solvable problems Author: Andrei Lapets Date: March 15, 2010 Abstract: A problem is in the class NP when it is possible to compute in polynomial time that a given solution corresponds to a given problem instance. Those problems for which it is possible to compute in polynomial time a solution for any problem instance are also in the class P. We consider a natural conjunction operation for problems that can be computed in polynomial time. We introduce the notion of an ``abundant" problem in P, and specify conditions under which the conjunction of two abundant problems in P produces a problem that is NP-complete. We discuss how this is related to multi-dimensional variants of common, efficiently computable graph problems.