P versus NP is considered as one of the most important open problems in computer science. This consists in knowing the answer of the following question: Is P equal to NP? A precise statement of the P versus NP problem was introduced independently by Stephen Cook and Leonid Levin. Since that date, all efforts to find a proof for this problem have failed. Given a positive integer x and a collection S of positive integers, MAXIMUM is the problem of deciding whether x is the maximum of S. We prove this problem is complete for P. Another major complexity classes are LOGSPACE, NLOGSPACE, coNP and EXP. Whether LOGSPACE = NLOGSPACE is a fundamental question that it is as important as it is unresolved. We show the problem MAXIMUM can be decided in l...