Description: Left-to-right part of definition of virtual deduction. (Contributed by Alan Sare, 21-Apr-2011) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | dfvd1imp | |- ( (. ph ->. ps ). -> ( ph -> ps ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | df-vd1 | |- ( (. ph ->. ps ). <-> ( ph -> ps ) ) |
|
| 2 | 1 | biimpi | |- ( (. ph ->. ps ). -> ( ph -> ps ) ) |