Description: Inference commuting a nested conjunction in antecedent. (Contributed by NM, 24-May-2006) (Proof shortened by Wolf Lammen, 24-Nov-2012)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | an32s.1 | |- ( ( ( ph /\ ps ) /\ ch ) -> th ) | |
| Assertion | ancom1s | |- ( ( ( ps /\ ph ) /\ ch ) -> th ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | an32s.1 | |- ( ( ( ph /\ ps ) /\ ch ) -> th ) | |
| 2 | pm3.22 | |- ( ( ps /\ ph ) -> ( ph /\ ps ) ) | |
| 3 | 2 1 | sylan | |- ( ( ( ps /\ ph ) /\ ch ) -> th ) |