Theorem cbviotavwOLD

Description: Obsolete version of cbviotavw as of 30-Sep-2024. (Contributed by Andrew Salmon, 1-Aug-2011) (Revised by Gino Giotto, 26-Jan-2024) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Hypothesis	cbviotavwOLD.1	$$⊢x=y\to \left(\phi \leftrightarrow \psi \right)$$
Assertion	cbviotavwOLD	$$⊢\left(\iota x|\phi \right)=\left(\iota y|\psi \right)$$

Proof

Step	Hyp	Ref	Expression
1		cbviotavwOLD.1	$$⊢x=y\to \left(\phi \leftrightarrow \psi \right)$$
2		nfv	$$⊢Ⅎy\phi$$
3		nfv	$$⊢Ⅎx\psi$$
4	1 2 3	cbviotaw	$$⊢\left(\iota x|\phi \right)=\left(\iota y|\psi \right)$$