Description: 3imp with outermost implication of the hypothesis a biconditional. (Contributed by Alan Sare, 6-Nov-2017)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | bi13imp23.1 | |- ( ph <-> ( ps -> ( ch -> th ) ) ) | |
| Assertion | bi13imp23 | |- ( ( ph /\ ps /\ ch ) -> th ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | bi13imp23.1 | |- ( ph <-> ( ps -> ( ch -> th ) ) ) | |
| 2 | 1 | biimpi | |- ( ph -> ( ps -> ( ch -> th ) ) ) | 
| 3 | 2 | 3imp | |- ( ( ph /\ ps /\ ch ) -> th ) |