Theorem nabi1i

Description: Constructor rule for -/\ . (Contributed by Anthony Hart, 2-Sep-2011)

	Ref	Expression
Hypotheses	nabi1i.1	|- ( ph <-> ps )
	nabi1i.2	|- ( ps -/\ ch )
Assertion	nabi1i	|- ( ph -/\ ch )

Proof

Step	Hyp	Ref	Expression
1		nabi1i.1	|- ( ph <-> ps )
2		nabi1i.2	|- ( ps -/\ ch )
3	1	bicomi	|- ( ps <-> ph )
4	3	nanbi1i	|- ( ( ps -/\ ch ) <-> ( ph -/\ ch ) )
5	2 4	mpbi	|- ( ph -/\ ch )