Description: Equivalence with a conjunction one of whose conjuncts is a consequence of the other. Deduction form. (Contributed by Zhi Wang, 24-Sep-2024)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | mpbiran3d.1 | |- ( ph -> ( ps <-> ( ch /\ th ) ) ) | |
| mpbiran3d.2 | |- ( ( ph /\ ch ) -> th ) | ||
| Assertion | mpbiran3d | |- ( ph -> ( ps <-> ch ) ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | mpbiran3d.1 | |- ( ph -> ( ps <-> ( ch /\ th ) ) ) | |
| 2 | mpbiran3d.2 | |- ( ( ph /\ ch ) -> th ) | |
| 3 | 1 | simprbda | |- ( ( ph /\ ps ) -> ch ) | 
| 4 | 3 | ex | |- ( ph -> ( ps -> ch ) ) | 
| 5 | 2 | ex | |- ( ph -> ( ch -> th ) ) | 
| 6 | 5 | ancld | |- ( ph -> ( ch -> ( ch /\ th ) ) ) | 
| 7 | 6 1 | sylibrd | |- ( ph -> ( ch -> ps ) ) | 
| 8 | 4 7 | impbid | |- ( ph -> ( ps <-> ch ) ) |