In a basis of a method of the item of information of equality to identities the definition of periodic function many variable is necessary. The decision is defined(determined) as comparisons on the module of the period of returning to initial equality. The research consists in the proof of necessity and sufficiency of the received decision. The proof of necessity consists in reception of identity. The proof of sufficiency consists in reception of expression, which statement the identity proves to be true by.
of a word: a method of the item of information, equality, identity, necessity, sufficiency