Description: Right-to-left part of definition of virtual deduction. (Contributed by Alan Sare, 21-Apr-2011) (Proof modification is discouraged.) (New usage is discouraged.)
Ref | Expression | ||
---|---|---|---|
Assertion | dfvd1impr | |- ( ( ph -> ps ) -> (. ph ->. ps ). ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-vd1 | |- ( (. ph ->. ps ). <-> ( ph -> ps ) ) |
|
2 | 1 | biimpri | |- ( ( ph -> ps ) -> (. ph ->. ps ). ) |