Theorem nanbi1i

Description: Introduce a right anti-conjunct to both sides of a logical equivalence. (Contributed by SF, 2-Jan-2018)

	Ref	Expression
Hypothesis	nanbii.1	|- ( ph <-> ps )
Assertion	nanbi1i	|- ( ( ph -/\ ch ) <-> ( ps -/\ ch ) )

Proof

Step	Hyp	Ref	Expression
1		nanbii.1	|- ( ph <-> ps )
2		nanbi1	|- ( ( ph <-> ps ) -> ( ( ph -/\ ch ) <-> ( ps -/\ ch ) ) )
3	1 2	ax-mp	|- ( ( ph -/\ ch ) <-> ( ps -/\ ch ) )