我试图证明:(forall x, a -> b) /\ (exists x, a) -> (exists x, b)。和推广:a(x) |- forall(x, a(x))我的公理:3) forall(x, a -> b) -> ((forall x, a) -> (forall x, b))
4) a -> (forall
. <-> Forall P []的目标,我想将Forall P []重写为True,然后为Forall P y重写True /\
(1)有一个定理Forall_nil Forall P [],但我如何使用它将Forall P []重写为True (2)似乎没有像True /\ P <-> P那样明显的简化/重写规则