Theorem csbvargi

Description: The proper substitution of a class for a setvar variable results in the class (if the class exists), in inference form of csbvarg . (Contributed by Giovanni Mascellani, 30-May-2019)

	Ref	Expression
Hypothesis	csbvargi.1	|- A e. _V
Assertion	csbvargi	|- [_ A / x ]_ x = A

Proof

Step	Hyp	Ref	Expression
1		csbvargi.1	|- A e. _V
2		csbvarg	|- ( A e. _V -> [_ A / x ]_ x = A )
3	1 2	ax-mp	|- [_ A / x ]_ x = A