 Which reads the object e is an element of the set A. Observe that this statement, if true, represents a piece of semantic information. It is wellformed, meaningful and truthful. (see entry on  semantic conceptions of information)  The concept of information is already at play in the basic building blocks of mathematics.The philosophical question “What are sets?” the answer to the ti esti question, is determined implicitly by the Zermelo-Fraenkel axioms (see entry on  set theory),  the first of which is that of extensionality: 