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Description: The unity element of a subring algebra. (Contributed by Thierry Arnoux, 24-Jul-2023)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | sral1r.a | |- ( ph -> A = ( ( subringAlg ` W ) ` S ) ) |
|
| sral1r.1 | |- ( ph -> .1. = ( 1r ` W ) ) |
||
| sral1r.s | |- ( ph -> S C_ ( Base ` W ) ) |
||
| Assertion | sra1r | |- ( ph -> .1. = ( 1r ` A ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | sral1r.a | |- ( ph -> A = ( ( subringAlg ` W ) ` S ) ) |
|
| 2 | sral1r.1 | |- ( ph -> .1. = ( 1r ` W ) ) |
|
| 3 | sral1r.s | |- ( ph -> S C_ ( Base ` W ) ) |
|
| 4 | eqidd | |- ( ph -> ( Base ` W ) = ( Base ` W ) ) |
|
| 5 | 1 3 | srabase | |- ( ph -> ( Base ` W ) = ( Base ` A ) ) |
| 6 | 1 3 | sramulr | |- ( ph -> ( .r ` W ) = ( .r ` A ) ) |
| 7 | 6 | oveqdr | |- ( ( ph /\ ( x e. ( Base ` W ) /\ y e. ( Base ` W ) ) ) -> ( x ( .r ` W ) y ) = ( x ( .r ` A ) y ) ) |
| 8 | 4 5 7 | rngidpropd | |- ( ph -> ( 1r ` W ) = ( 1r ` A ) ) |
| 9 | 2 8 | eqtrd | |- ( ph -> .1. = ( 1r ` A ) ) |