Description: Obsolete version of expt as of 25-May-2026. Exportation theorem pm3.3 (closed form of ex ) expressed with primitive connectives. (Contributed by NM, 28-Dec-1992) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | exptOLD | |- ( ( -. ( ph -> -. ps ) -> ch ) -> ( ph -> ( ps -> ch ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | pm3.2im | |- ( ph -> ( ps -> -. ( ph -> -. ps ) ) ) |
|
| 2 | 1 | imim1d | |- ( ph -> ( ( -. ( ph -> -. ps ) -> ch ) -> ( ps -> ch ) ) ) |
| 3 | 2 | com12 | |- ( ( -. ( ph -> -. ps ) -> ch ) -> ( ph -> ( ps -> ch ) ) ) |