fv-exyd

Theorem.

Arguments:

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

Hypotheses:

(phito(psitoforallxpsi))
(y bound in phi)

Assertions:

(phito(existsypsitoforallxexistsypsi))

Proof:

Hyp Ref Line Expr
Hypo1(phito(psitoforallxpsi))
2(y bound in phi)
1, 2im.bldexd3(phito(existsypsitoexistsyforallxpsi))
exalswap4(existsyforallxpsitoforallxexistsypsi)
3, 4rpi335(phito(existsypsitoforallxexistsypsi))