State the Dirichilet's pigeonhole principle in terms of sets (not informally like it sometimes presented). And then prove it with the definiton of a finite set as a set which has no proper subset which can be placed into one-to-one correspondence.
State the Dirichilet's pigeonhole principle in terms of sets (not informally like it sometimes presented). And then prove it with the definiton of a finite set as a set which has no proper subset which can be placed into one-to-one correspondence.