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 ) ) ) |
| 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 ) ) ) |