Theorem nabi2i

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

	Ref	Expression
Hypotheses	nabi2i.1	$$⊢\phi \leftrightarrow \psi$$
	nabi2i.2	$$⊢\left(\chi ⊼\psi \right)$$
Assertion	nabi2i	$$⊢\left(\chi ⊼\phi \right)$$

Proof

Step	Hyp	Ref	Expression
1		nabi2i.1	$$⊢\phi \leftrightarrow \psi$$
2		nabi2i.2	$$⊢\left(\chi ⊼\psi \right)$$
3	1	bicomi	$$⊢\psi \leftrightarrow \phi$$
4	3	nanbi2i	$$⊢\left(\chi ⊼\psi \right)\leftrightarrow \left(\chi ⊼\phi \right)$$
5	2 4	mpbi	$$⊢\left(\chi ⊼\phi \right)$$