Theorem spv

Specialization, using implicit substitution. Usage of this theorem is discouraged because it depends on [ax-13]. Use the weaker spvv if possible. (Contributed by NM, 30-Aug-1993.) (New usage is discouraged.)

Hypothesis
spv.1
\( \vdash x = y' \rightarrow (\varphi \leftrightarrow \psi) \)
Conclusion
\( \vdash \forall x \, \varphi \rightarrow \psi \)
Proof
spv.1
biimpd _
\( \vdash x = y' \rightarrow \varphi \rightarrow \psi \)
spimv _