Description: Swap antecedents of ax-frege58a . Proposition 60 of Frege1879 p. 52. (Contributed by RP, 17-Apr-2020) (Proof modification is discouraged.)
Ref | Expression | ||
---|---|---|---|
Assertion | frege60a | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | frege58acor | |
|
2 | ifpimim | |
|
3 | 1 2 | syl6 | |
4 | frege12 | |
|
5 | 3 4 | ax-mp | |