Description: A closed form of com4r . Proposition 15 of Frege1879 p. 38. (Contributed by RP, 24-Dec-2019) (Proof modification is discouraged.)
Ref | Expression | ||
---|---|---|---|
Assertion | frege15 | |- ( ( ph -> ( ps -> ( ch -> ( th -> ta ) ) ) ) -> ( th -> ( ph -> ( ps -> ( ch -> ta ) ) ) ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | frege14 | |- ( ( ph -> ( ps -> ( ch -> ( th -> ta ) ) ) ) -> ( ph -> ( th -> ( ps -> ( ch -> ta ) ) ) ) ) |
|
2 | frege12 | |- ( ( ( ph -> ( ps -> ( ch -> ( th -> ta ) ) ) ) -> ( ph -> ( th -> ( ps -> ( ch -> ta ) ) ) ) ) -> ( ( ph -> ( ps -> ( ch -> ( th -> ta ) ) ) ) -> ( th -> ( ph -> ( ps -> ( ch -> ta ) ) ) ) ) ) |
|
3 | 1 2 | ax-mp | |- ( ( ph -> ( ps -> ( ch -> ( th -> ta ) ) ) ) -> ( th -> ( ph -> ( ps -> ( ch -> ta ) ) ) ) ) |