Description: Definition of virtual deduction. (Contributed by Alan Sare, 21-Apr-2011) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-vd1 | |- ( (. ph ->. ps ). <-> ( ph -> ps ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | wph | |- ph |
|
| 1 | wps | |- ps |
|
| 2 | 0 1 | wvd1 | |- (. ph ->. ps ). |
| 3 | 0 1 | wi | |- ( ph -> ps ) |
| 4 | 2 3 | wb | |- ( (. ph ->. ps ). <-> ( ph -> ps ) ) |