Is $\lnot\forall x(Px \lor Qx) \equiv \lnot(\forall x(Px \lor Qx))? $
I'm trying to figure out how to apply the distributive law for universal quantifiers when the universal quantifier is negated, and the book that I'm studying doesn't specify.
If they're equivalent, then applying the law should result in $\lnot((\forall x Px) \lor (\forall x \lor Qx))$.
If they're not equivalent, maybe in $\lnot\forall x Px \lor \lnot \forall Qx$.
Yes, they are equivalent, and they are both equivalent to
$$\exists x \textrm{ such that }(\lnot Px) \wedge (\lnot Qx)$$