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*Proposition:*
Two sets have *same size*, if there is a
bijection between:

One set isAandBare of same size : <=>existsf:f:A->^{bijective}B.

One set isAis not larger thanB: <=>existsf:f:A->^{injective}B.

Ais smaller thanB: <=>( Ais not larger thanB) /\ ~(AandBhave same size).

Author: Wolfgang Schreiner

Last Modification: December 7, 1999