Description: Theorem *3.2 of WhiteheadRussell p. 111, expressed with primitive connectives (see pm3.2 ). (Contributed by NM, 29-Dec-1992) (Proof shortened by Josh Purinton, 29-Dec-2000)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | pm3.2im | |- ( ph -> ( ps -> -. ( ph -> -. ps ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | pm2.27 | |- ( ph -> ( ( ph -> -. ps ) -> -. ps ) ) |
|
| 2 | 1 | con2d | |- ( ph -> ( ps -> -. ( ph -> -. ps ) ) ) |