spec-ex

Theorem.

Arguments:

x (sv), phi (pr),

Assertions:

(phitoexistsxphi)

Proof:

Hyp Ref Line Expr
ax41(forallxlnotphitolnotphi)
1con>2(phitolnotforallxlnotphi)
df-ex3(existsxphileftrightarrowlnotforallxlnotphi)
2, 3brpi22<4(phitoexistsxphi)