We have

A = ∀x¬P(x) ⊻ ∀yQ(y)

B = ∃xP(x) ⇔ ∀yQ(y)

Are A and ¬B equal? I get that they are.

Is it correct? I have solved it like this:

First we negate the B:

∃xP(x) ⇔ ∀yQ(y)

¬∃xP(x) ⇔ ¬∀yQ(y)

then we get

∀x¬P(x) ⇔ ∃y¬Q(y)

And then we insert something. (for example):

P(x) x is divisible by 2

Q(y) y is not divisible by 2

For both A and not B i get zero. So they are equal.

Is my thinking correct?