Theorem nexd

Deduction for generalization rule for negated wff. (Contributed by Mario Carneiro, 24-Sep-2016.)

Hypotheses
nexd.1
\( \vdash \Finv x \, \varphi \)
nexd.2
\( \vdash \varphi \rightarrow \neg \psi \)
Conclusion
\( \vdash \varphi \rightarrow \neg \exists x \, \psi \)
Proof
nexd.1
l1
nf5ri _
nexd.2
nexdh l1 _