回复：What is relation? your 1 to 6 is just my proof. my 2011/2 out

来源: 于 2011-06-01 08:31:32 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

ok for the term "relation".

but in my proof, i used only the fact f(x) (or r(x) if you like) is unique. not bijection.