Metamath Proof Explorer


Theorem frege85

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 ) ) )

Proof

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 ) ) )