反证法是错误的
反证法是错误的。这里有真、假和不可判定的情况。<p>让我来解释一下它是如何运作的。<p>p => q 并不一定意味着 ¬q => ¬p。这里有三种情况。如果 ¬q 为真，那么 p 也可能是不可判定的。
查看原文
Proof by contrapositive is wrong. There is a true, false and undecidable case also.<p>Let me explain how it works.<p>p. =>. q. does not necessarily imply not q ==> not p. There are three cases here. If not q is true, then p can also be undecidable.