Theorem in3

Description: The virtual deduction introduction rule of converting the end virtual hypothesis of 3 virtual hypotheses into an antecedent. (Contributed by Alan Sare, 12-Jun-2011) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Hypothesis	in3.1	$$⊢\left(\phi ,\psi ,\chi \to \theta \right)$$
Assertion	in3	$$⊢\left(\phi ,\psi \to \left(\chi \to \theta \right)\right)$$

Proof

Step	Hyp	Ref	Expression
1		in3.1	$$⊢\left(\phi ,\psi ,\chi \to \theta \right)$$
2	1	dfvd3i	$$⊢\phi \to \left(\psi \to \left(\chi \to \theta \right)\right)$$
3	2	dfvd2ir	$$⊢\left(\phi ,\psi \to \left(\chi \to \theta \right)\right)$$