fv.eqal

Theorem.

Arguments:

x (sv), phi (pr),

Hypotheses:

(x bound in phi)

Assertions:

(phileftrightarrowforallxphi)

Proof:

Hyp Ref Line Expr
Hypo1(x bound in phi)
1df-Bvp2(phitoforallxphi)
ax43(forallxphitophi)
2, 3>bii4(phileftrightarrowforallxphi)