Metamath Proof Explorer


Theorem alephfplem2

Description: Lemma for alephfp . (Contributed by NM, 6-Nov-2004)

Ref Expression
Hypothesis alephfplem.1
|- H = ( rec ( aleph , _om ) |` _om )
Assertion alephfplem2
|- ( w e. _om -> ( H ` suc w ) = ( aleph ` ( H ` w ) ) )

Proof

Step Hyp Ref Expression
1 alephfplem.1
 |-  H = ( rec ( aleph , _om ) |` _om )
2 frsuc
 |-  ( w e. _om -> ( ( rec ( aleph , _om ) |` _om ) ` suc w ) = ( aleph ` ( ( rec ( aleph , _om ) |` _om ) ` w ) ) )
3 1 fveq1i
 |-  ( H ` suc w ) = ( ( rec ( aleph , _om ) |` _om ) ` suc w )
4 1 fveq1i
 |-  ( H ` w ) = ( ( rec ( aleph , _om ) |` _om ) ` w )
5 4 fveq2i
 |-  ( aleph ` ( H ` w ) ) = ( aleph ` ( ( rec ( aleph , _om ) |` _om ) ` w ) )
6 2 3 5 3eqtr4g
 |-  ( w e. _om -> ( H ` suc w ) = ( aleph ` ( H ` w ) ) )