Metamath Proof Explorer


Theorem bnj1522

Description: Well-founded recursion, part 3 of 3. The proof has been taken from Chapter 4 of Don Monk's notes on Set Theory. See http://euclid.colorado.edu/~monkd/setth.pdf . (Contributed by Jonathan Ben-Naim, 3-Jun-2011) (New usage is discouraged.)

Ref Expression
Hypotheses bnj1522.1
|- B = { d | ( d C_ A /\ A. x e. d _pred ( x , A , R ) C_ d ) }
bnj1522.2
|- Y = <. x , ( f |` _pred ( x , A , R ) ) >.
bnj1522.3
|- C = { f | E. d e. B ( f Fn d /\ A. x e. d ( f ` x ) = ( G ` Y ) ) }
bnj1522.4
|- F = U. C
Assertion bnj1522
|- ( ( R _FrSe A /\ H Fn A /\ A. x e. A ( H ` x ) = ( G ` <. x , ( H |` _pred ( x , A , R ) ) >. ) ) -> F = H )

Proof

Step Hyp Ref Expression
1 bnj1522.1
 |-  B = { d | ( d C_ A /\ A. x e. d _pred ( x , A , R ) C_ d ) }
2 bnj1522.2
 |-  Y = <. x , ( f |` _pred ( x , A , R ) ) >.
3 bnj1522.3
 |-  C = { f | E. d e. B ( f Fn d /\ A. x e. d ( f ` x ) = ( G ` Y ) ) }
4 bnj1522.4
 |-  F = U. C
5 biid
 |-  ( ( R _FrSe A /\ H Fn A /\ A. x e. A ( H ` x ) = ( G ` <. x , ( H |` _pred ( x , A , R ) ) >. ) ) <-> ( R _FrSe A /\ H Fn A /\ A. x e. A ( H ` x ) = ( G ` <. x , ( H |` _pred ( x , A , R ) ) >. ) ) )
6 biid
 |-  ( ( ( R _FrSe A /\ H Fn A /\ A. x e. A ( H ` x ) = ( G ` <. x , ( H |` _pred ( x , A , R ) ) >. ) ) /\ F =/= H ) <-> ( ( R _FrSe A /\ H Fn A /\ A. x e. A ( H ` x ) = ( G ` <. x , ( H |` _pred ( x , A , R ) ) >. ) ) /\ F =/= H ) )
7 biid
 |-  ( ( ( ( R _FrSe A /\ H Fn A /\ A. x e. A ( H ` x ) = ( G ` <. x , ( H |` _pred ( x , A , R ) ) >. ) ) /\ F =/= H ) /\ x e. A /\ ( F ` x ) =/= ( H ` x ) ) <-> ( ( ( R _FrSe A /\ H Fn A /\ A. x e. A ( H ` x ) = ( G ` <. x , ( H |` _pred ( x , A , R ) ) >. ) ) /\ F =/= H ) /\ x e. A /\ ( F ` x ) =/= ( H ` x ) ) )
8 eqid
 |-  { x e. A | ( F ` x ) =/= ( H ` x ) } = { x e. A | ( F ` x ) =/= ( H ` x ) }
9 biid
 |-  ( ( ( ( ( R _FrSe A /\ H Fn A /\ A. x e. A ( H ` x ) = ( G ` <. x , ( H |` _pred ( x , A , R ) ) >. ) ) /\ F =/= H ) /\ x e. A /\ ( F ` x ) =/= ( H ` x ) ) /\ y e. { x e. A | ( F ` x ) =/= ( H ` x ) } /\ A. z e. { x e. A | ( F ` x ) =/= ( H ` x ) } -. z R y ) <-> ( ( ( ( R _FrSe A /\ H Fn A /\ A. x e. A ( H ` x ) = ( G ` <. x , ( H |` _pred ( x , A , R ) ) >. ) ) /\ F =/= H ) /\ x e. A /\ ( F ` x ) =/= ( H ` x ) ) /\ y e. { x e. A | ( F ` x ) =/= ( H ` x ) } /\ A. z e. { x e. A | ( F ` x ) =/= ( H ` x ) } -. z R y ) )
10 1 2 3 4 5 6 7 8 9 bnj1523
 |-  ( ( R _FrSe A /\ H Fn A /\ A. x e. A ( H ` x ) = ( G ` <. x , ( H |` _pred ( x , A , R ) ) >. ) ) -> F = H )