Description: Inference rule. Copy of con4i with a different proof. (Contributed by Wolf Lammen, 17-Dec-2018) (New usage is discouraged.) (Proof modification is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | wl-luk-con4i.1 | ⊢ ( ¬ 𝜑 → ¬ 𝜓 ) | |
| Assertion | wl-luk-con4i | ⊢ ( 𝜓 → 𝜑 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | wl-luk-con4i.1 | ⊢ ( ¬ 𝜑 → ¬ 𝜓 ) | |
| 2 | ax-luk3 | ⊢ ( 𝜓 → ( ¬ 𝜓 → 𝜑 ) ) | |
| 3 | 1 2 | wl-luk-imtrid | ⊢ ( 𝜓 → ( ¬ 𝜑 → 𝜑 ) ) |
| 4 | 3 | wl-luk-pm2.18d | ⊢ ( 𝜓 → 𝜑 ) |