Description: A 2-antecedent nested implication implies its virtual deduction form. (Contributed by Alan Sare, 21-Apr-2011) (Proof modification is discouraged.) (New usage is discouraged.)
Ref | Expression | ||
---|---|---|---|
Assertion | dfvd2impr | |- ( ( ph -> ( ps -> ch ) ) -> (. ph ,. ps ->. ch ). ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dfvd2 | |- ( (. ph ,. ps ->. ch ). <-> ( ph -> ( ps -> ch ) ) ) |
|
2 | 1 | biimpri | |- ( ( ph -> ( ps -> ch ) ) -> (. ph ,. ps ->. ch ). ) |