Description: Deduction based on reductio ad absurdum. Copy of pm2.18d with a different proof. (Contributed by Wolf Lammen, 17-Dec-2018) (New usage is discouraged.) (Proof modification is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | wl-luk-pm2.18d.1 | |- ( ph -> ( -. ps -> ps ) ) |
|
| Assertion | wl-luk-pm2.18d | |- ( ph -> ps ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | wl-luk-pm2.18d.1 | |- ( ph -> ( -. ps -> ps ) ) |
|
| 2 | ax-luk2 | |- ( ( -. ps -> ps ) -> ps ) |
|
| 3 | 1 2 | wl-luk-syl | |- ( ph -> ps ) |