Theorem eqeq2i

Description: Inference from equality to equivalence of equalities. (Contributed by NM, 26-May-1993)

	Ref	Expression
Hypothesis	eqeq2i.1	$$⊢A=B$$
Assertion	eqeq2i	$$⊢C=A\leftrightarrow C=B$$

Proof

Step	Hyp	Ref	Expression
1		eqeq2i.1	$$⊢A=B$$
2		eqeq2	$$⊢A=B\to \left(C=A\leftrightarrow C=B\right)$$
3	1 2	ax-mp	$$⊢C=A\leftrightarrow C=B$$