Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
$$\lnot \forall y: Y.A\vdash \exists y: Y.(A\rightarrow B)$$
Need to prove that LHS entails RHS, however I'm confused as to how to do it. Never used a negation on a universal quantifier before.
Any help would be appreciated.
HINT $$\lnot \forall y: Y.A \equiv \exists y: \lnot Y.A$$
Required, but never shown