Theorem csbeq2i

Description: Formula-building inference for class substitution. (Contributed by NM, 10-Nov-2005) (Revised by Mario Carneiro, 1-Sep-2015)

	Ref	Expression
Hypothesis	csbeq2i.1	$$⊢B=C$$
Assertion	csbeq2i	$$⊢⦋A/x⦌B=⦋A/x⦌C$$

Proof

Step	Hyp	Ref	Expression
1		csbeq2i.1	$$⊢B=C$$
2	1	a1i	$$⊢\top \to B=C$$
3	2	csbeq2dv	$$⊢\top \to ⦋A/x⦌B=⦋A/x⦌C$$
4	3	mptru	$$⊢⦋A/x⦌B=⦋A/x⦌C$$