Theorem equcomiv

Description: Weaker form of equcomi with a disjoint variable condition on x , y . This is an intermediate step and equcomi is fully recovered later. (Contributed by BJ, 7-Dec-2020)

	Ref	Expression
Assertion	equcomiv	|- ( x = y -> y = x )

Proof

Step	Hyp	Ref	Expression
1		equid	|- x = x
2		ax7v2	|- ( x = y -> ( x = x -> y = x ) )
3	1 2	mpi	|- ( x = y -> y = x )