( ∀x) P ≡ ¬(∃x(¬P))
$(\forall x)P \equiv \neg (\exists x(\neg P))$
全称量词 Universal Quantifier
for all values of in the (restricted) domain
存在量词 Existential Quantifier
There exists (at least) an element in the domain such that
德·摩根定律 De Morgan’s Laws for quantifiers:
p→q ≡ ¬p∨q
$p \rightarrow q \equiv \neg p \vee q$
蕴涵定律 Implication Law:
REF: https://blog.csdn.net/liteng607/article/details/104649755