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Metamath Proof Explorer

Theorem opprdomn

Description: The opposite of a domain is also a domain. (Contributed by Mario Carneiro, 15-Jun-2015)

		Ref	Expression
	Hypothesis	opprdomn.1	$⊢ O = {opp}_{r} (R)$
	Assertion	opprdomn	$⊢ R \in Domn \to O \in Domn$

Step	Hyp	Ref	Expression
1		opprdomn.1	$⊢ O = {opp}_{r} (R)$
2	1	opprdomnb	$⊢ R \in Domn \leftrightarrow O \in Domn$
3	2	biimpi	$⊢ R \in Domn \to O \in Domn$