Description: Commuted form of frege77 . Proposition 85 of Frege1879 p. 66. (Contributed by RP, 1-Jul-2020) (Revised by RP, 5-Jul-2020) (Proof modification is discouraged.)
Ref | Expression | ||
---|---|---|---|
Hypotheses | frege84.x | |- X e. U |
|
frege84.y | |- Y e. V |
||
frege84.r | |- R e. W |
||
frege84.a | |- A e. B |
||
Assertion | frege85 | |- ( X ( t+ ` R ) Y -> ( A. z ( X R z -> z e. A ) -> ( R hereditary A -> Y e. A ) ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | frege84.x | |- X e. U |
|
2 | frege84.y | |- Y e. V |
|
3 | frege84.r | |- R e. W |
|
4 | frege84.a | |- A e. B |
|
5 | 1 2 3 4 | frege77 | |- ( X ( t+ ` R ) Y -> ( R hereditary A -> ( A. z ( X R z -> z e. A ) -> Y e. A ) ) ) |
6 | frege12 | |- ( ( X ( t+ ` R ) Y -> ( R hereditary A -> ( A. z ( X R z -> z e. A ) -> Y e. A ) ) ) -> ( X ( t+ ` R ) Y -> ( A. z ( X R z -> z e. A ) -> ( R hereditary A -> Y e. A ) ) ) ) |
|
7 | 5 6 | ax-mp | |- ( X ( t+ ` R ) Y -> ( A. z ( X R z -> z e. A ) -> ( R hereditary A -> Y e. A ) ) ) |