Metamath Proof Explorer

Theorem in1

Description: Inference form of df-vd1 . Virtual deduction introduction rule of converting the virtual hypothesis of a 1-virtual hypothesis virtual deduction into an antecedent. (Contributed by Alan Sare, 14-Nov-2011) (Proof modification is discouraged.) (New usage is discouraged.)

Ref Expression
Hypothesis in1.1 φ ψ
Assertion in1 φ ψ


Step Hyp Ref Expression
1 in1.1 φ ψ
2 df-vd1 φ ψ φ ψ
3 1 2 mpbi φ ψ