Theorem nabi12i

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

	Ref	Expression
Hypotheses	nabi12i.1	$$⊢\phi \leftrightarrow \psi$$
	nabi12i.2	$$⊢\chi \leftrightarrow \theta$$
	nabi12i.3	$$⊢\left(\psi ⊼\theta \right)$$
Assertion	nabi12i	$$⊢\left(\phi ⊼\chi \right)$$

Proof

Step	Hyp	Ref	Expression
1		nabi12i.1	$$⊢\phi \leftrightarrow \psi$$
2		nabi12i.2	$$⊢\chi \leftrightarrow \theta$$
3		nabi12i.3	$$⊢\left(\psi ⊼\theta \right)$$
4	1 3	nabi1i	$$⊢\left(\phi ⊼\theta \right)$$
5	2 4	nabi2i	$$⊢\left(\phi ⊼\chi \right)$$