Metamath Proof Explorer


Theorem frege107

Description: Proposition 107 of Frege1879 p. 74. (Contributed by RP, 7-Jul-2020) (Proof modification is discouraged.)

Ref Expression
Hypothesis frege107.v
|- V e. A
Assertion frege107
|- ( ( Z ( ( t+ ` R ) u. _I ) Y -> ( Y R V -> Z ( t+ ` R ) V ) ) -> ( Z ( ( t+ ` R ) u. _I ) Y -> ( Y R V -> Z ( ( t+ ` R ) u. _I ) V ) ) )

Proof

Step Hyp Ref Expression
1 frege107.v
 |-  V e. A
2 1 frege106
 |-  ( Z ( t+ ` R ) V -> Z ( ( t+ ` R ) u. _I ) V )
3 frege7
 |-  ( ( Z ( t+ ` R ) V -> Z ( ( t+ ` R ) u. _I ) V ) -> ( ( Z ( ( t+ ` R ) u. _I ) Y -> ( Y R V -> Z ( t+ ` R ) V ) ) -> ( Z ( ( t+ ` R ) u. _I ) Y -> ( Y R V -> Z ( ( t+ ` R ) u. _I ) V ) ) ) )
4 2 3 ax-mp
 |-  ( ( Z ( ( t+ ` R ) u. _I ) Y -> ( Y R V -> Z ( t+ ` R ) V ) ) -> ( Z ( ( t+ ` R ) u. _I ) Y -> ( Y R V -> Z ( ( t+ ` R ) u. _I ) V ) ) )