Description: Commutation of antecedents. Swap 2nd and 3rd. Deduction associated with com12 . (Contributed by NM, 27-Dec-1992) (Proof shortened by Wolf Lammen, 4-Aug-2012)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | com3.1 | |- ( ph -> ( ps -> ( ch -> th ) ) ) |
|
| Assertion | com23 | |- ( ph -> ( ch -> ( ps -> th ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | com3.1 | |- ( ph -> ( ps -> ( ch -> th ) ) ) |
|
| 2 | pm2.27 | |- ( ch -> ( ( ch -> th ) -> th ) ) |
|
| 3 | 1 2 | syl9 | |- ( ph -> ( ch -> ( ps -> th ) ) ) |