A principle that links the results of quantum theory for a system with the results of classical physics for that system. There are several statements of such a principle. One is that in the limit of large quantum numbers the results of quantum-mechanical calculations go over to the classical result. More generally, the correspondence principle states that there is a correspondence between the results using quantum theory and those using classical theory. The principle was stated by Niels Bohr in 1920 but had been used by him since 1913. There are some important features of quantum theory, such as the Pauli exclusion principle, that the correspondence principle does not apply to.