fv.eqexd

Theorem.

Arguments:

x (sv), phi (pr), psi (pr),

Hypotheses:

(phito(psitoforallxpsi))
(x bound in phi)

Assertions:

(phito(existsxpsitopsi))

Proof:

Hyp Ref Line Expr
Hypo1(phito(psitoforallxpsi))
2(x bound in phi)
2df-Bvp3(phitoforallxphi)
1im.bldal4(forallxphitoforallx(psitoforallxpsi))
fv.eqext5(forallx(psitoforallxpsi)to(existsxpsitopsi))
3, 4syl6(phitoforallx(psitoforallxpsi))
5, 6syl7(phito(existsxpsitopsi))