Metamath Proof Explorer


Theorem wl-luk-a1i

Description: Inference rule. Copy of a1i with a different proof. (Contributed by Wolf Lammen, 17-Dec-2018) (New usage is discouraged.) (Proof modification is discouraged.)

Ref Expression
Hypothesis wl-luk-a1i.1 𝜑
Assertion wl-luk-a1i ( 𝜓𝜑 )

Proof

Step Hyp Ref Expression
1 wl-luk-a1i.1 𝜑
2 1 wl-luk-pm2.24i ( ¬ 𝜑 → ¬ 𝜓 )
3 2 wl-luk-con4i ( 𝜓𝜑 )