Theorem unieqi

Description: Inference of equality of two class unions. (Contributed by NM, 30-Aug-1993)

	Ref	Expression
Hypothesis	unieqi.1	$$⊢A=B$$
Assertion	unieqi	$$⊢\bigcup A=\bigcup B$$

Proof

Step	Hyp	Ref	Expression
1		unieqi.1	$$⊢A=B$$
2		unieq	$$⊢A=B\to \bigcup A=\bigcup B$$
3	1 2	ax-mp	$$⊢\bigcup A=\bigcup B$$