how to prove?
更新1:
∃x∀yP(x, y) → ∀y∃xP(x, y) is a tautology. how to prove?
∃x∀yP(x, y) → ∀y∃xP(x, y) is a tautology. how to prove?
收錄日期: 2021-05-01 15:04:48
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20141117000051KK00026