Description: Biconditional contraposition variation. This proof is con5VD automatically translated and minimized. (Contributed by Alan Sare, 21-Apr-2013) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | con5 | |- ( ( ph <-> -. ps ) -> ( -. ph -> ps ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | biimpr | |- ( ( ph <-> -. ps ) -> ( -. ps -> ph ) ) |
|
| 2 | 1 | con1d | |- ( ( ph <-> -. ps ) -> ( -. ph -> ps ) ) |