Metamath Proof Explorer

Theorem wfrdmss

Description: The domain of the well-founded recursion generator is a subclass of A . (Contributed by Scott Fenton, 21-Apr-2011)

Ref Expression
Hypothesis wfrlem6.1 
|- F = wrecs ( R , A , G )
Assertion wfrdmss 
|- dom F C_ A

Proof

Step Hyp Ref Expression
1 wfrlem6.1 
 |-  F = wrecs ( R , A , G )
2 df-wrecs 
 |-  wrecs ( R , A , G ) = U. { f | E. x ( f Fn x /\ ( x C_ A /\ A. y e. x Pred ( R , A , y ) C_ x ) /\ A. y e. x ( f ` y ) = ( G ` ( f |` Pred ( R , A , y ) ) ) ) }
3 1 2 eqtri 
 |-  F = U. { f | E. x ( f Fn x /\ ( x C_ A /\ A. y e. x Pred ( R , A , y ) C_ x ) /\ A. y e. x ( f ` y ) = ( G ` ( f |` Pred ( R , A , y ) ) ) ) }
4 3 dmeqi 
 |-  dom F = dom U. { f | E. x ( f Fn x /\ ( x C_ A /\ A. y e. x Pred ( R , A , y ) C_ x ) /\ A. y e. x ( f ` y ) = ( G ` ( f |` Pred ( R , A , y ) ) ) ) }
5 dmuni 
 |-  dom U. { f | E. x ( f Fn x /\ ( x C_ A /\ A. y e. x Pred ( R , A , y ) C_ x ) /\ A. y e. x ( f ` y ) = ( G ` ( f |` Pred ( R , A , y ) ) ) ) } = U_ g e. { f | E. x ( f Fn x /\ ( x C_ A /\ A. y e. x Pred ( R , A , y ) C_ x ) /\ A. y e. x ( f ` y ) = ( G ` ( f |` Pred ( R , A , y ) ) ) ) } dom g
6 4 5 eqtri 
 |-  dom F = U_ g e. { f | E. x ( f Fn x /\ ( x C_ A /\ A. y e. x Pred ( R , A , y ) C_ x ) /\ A. y e. x ( f ` y ) = ( G ` ( f |` Pred ( R , A , y ) ) ) ) } dom g
7 iunss 
 |-  ( U_ g e. { f | E. x ( f Fn x /\ ( x C_ A /\ A. y e. x Pred ( R , A , y ) C_ x ) /\ A. y e. x ( f ` y ) = ( G ` ( f |` Pred ( R , A , y ) ) ) ) } dom g C_ A <-> A. g e. { f | E. x ( f Fn x /\ ( x C_ A /\ A. y e. x Pred ( R , A , y ) C_ x ) /\ A. y e. x ( f ` y ) = ( G ` ( f |` Pred ( R , A , y ) ) ) ) } dom g C_ A )
8 eqid 
 |-  { f | E. x ( f Fn x /\ ( x C_ A /\ A. y e. x Pred ( R , A , y ) C_ x ) /\ A. y e. x ( f ` y ) = ( G ` ( f |` Pred ( R , A , y ) ) ) ) } = { f | E. x ( f Fn x /\ ( x C_ A /\ A. y e. x Pred ( R , A , y ) C_ x ) /\ A. y e. x ( f ` y ) = ( G ` ( f |` Pred ( R , A , y ) ) ) ) }
9 8 wfrlem3 
 |-  ( g e. { f | E. x ( f Fn x /\ ( x C_ A /\ A. y e. x Pred ( R , A , y ) C_ x ) /\ A. y e. x ( f ` y ) = ( G ` ( f |` Pred ( R , A , y ) ) ) ) } -> dom g C_ A )
10 7 9 mprgbir 
 |-  U_ g e. { f | E. x ( f Fn x /\ ( x C_ A /\ A. y e. x Pred ( R , A , y ) C_ x ) /\ A. y e. x ( f ` y ) = ( G ` ( f |` Pred ( R , A , y ) ) ) ) } dom g C_ A
11 6 10 eqsstri 
 |-  dom F C_ A