Axiom /Postulate(公理,基本原理), Theorem, Lemma(引理), premises(前提)
否定后段式
-|q
p --> q
----------
-| p
三段式
p --> q
q --> r
-------
So p --> r
\-/ x
- Ex
- Existential Generalization(EG)
P(c) for some element c
------------------------
E x
-
Direct proof: p --
-
Contradiction: p^
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Case: (分类讨论)
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Equivalence
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Vacuous Proof: p-->q. If q is false, p-->q is t
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Trival : p-->q. If is q is true, p-->q is f