Description: Syllogism inference combined with a biconditional. (Contributed by BJ, 25-Apr-2019)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | sylanblrc.1 | |- ( ph -> ps ) | |
| sylanblrc.2 | |- ch | ||
| sylanblrc.3 | |- ( th <-> ( ps /\ ch ) ) | ||
| Assertion | sylanblrc | |- ( ph -> th ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | sylanblrc.1 | |- ( ph -> ps ) | |
| 2 | sylanblrc.2 | |- ch | |
| 3 | sylanblrc.3 | |- ( th <-> ( ps /\ ch ) ) | |
| 4 | 2 | a1i | |- ( ph -> ch ) | 
| 5 | 1 4 3 | sylanbrc | |- ( ph -> th ) |