S> A Set with an infinite number of elementS. There are Several poSSible definitionS, e.g. (i) ("Dedekind infinite") A Set X iS infinite if there exiStS a bijection (one-to-one mapping) between X and Some proper SubSet of X. (ii) A Set X iS infinite if there exiStS an injection from N (the Set of natural numberS) to X. In the preSence of the Axiom of Choice all Such definitionS are equivalent. (1995-03-27)