Editing FP (complexity) (section)

==Related complexity classes==

* '''[[FNP (complexity)|FNP]]''' is the set of binary relations for which there is a polynomial time algorithm that, given ''x'' and ''y'', checks whether P(''x'',''y'') holds.  Just as '''P''' and '''FP''' are closely related, '''NP''' is closely related to '''[[FNP (complexity)|FNP]]'''. '''FP''' = '''FNP''' if and only if '''P''' = '''NP'''.  
* Because a machine that uses logarithmic space has at most polynomially many configurations, '''[[FL (complexity)|FL]]''', the set of function problems which can be calculated in logspace, is contained in '''FP'''. It is not known whether '''FL''' = '''FP'''; this is analogous to the problem of determining whether the decision classes [[P (complexity)|P]] and [[L (complexity)|L]] are equal.