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Description: Generated subfields preserve subset ordering. ( see lspss and spanss ) (Contributed by Thierry Arnoux, 15-Jan-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | fldgenval.1 | |- B = ( Base ` F ) |
|
| fldgenval.2 | |- ( ph -> F e. DivRing ) |
||
| fldgenval.3 | |- ( ph -> S C_ B ) |
||
| fldgenss.t | |- ( ph -> T C_ S ) |
||
| Assertion | fldgenss | |- ( ph -> ( F fldGen T ) C_ ( F fldGen S ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | fldgenval.1 | |- B = ( Base ` F ) |
|
| 2 | fldgenval.2 | |- ( ph -> F e. DivRing ) |
|
| 3 | fldgenval.3 | |- ( ph -> S C_ B ) |
|
| 4 | fldgenss.t | |- ( ph -> T C_ S ) |
|
| 5 | 4 | adantr | |- ( ( ph /\ S C_ a ) -> T C_ S ) |
| 6 | simpr | |- ( ( ph /\ S C_ a ) -> S C_ a ) |
|
| 7 | 5 6 | sstrd | |- ( ( ph /\ S C_ a ) -> T C_ a ) |
| 8 | 7 | ex | |- ( ph -> ( S C_ a -> T C_ a ) ) |
| 9 | 8 | adantr | |- ( ( ph /\ a e. ( SubDRing ` F ) ) -> ( S C_ a -> T C_ a ) ) |
| 10 | 9 | ss2rabdv | |- ( ph -> { a e. ( SubDRing ` F ) | S C_ a } C_ { a e. ( SubDRing ` F ) | T C_ a } ) |
| 11 | intss | |- ( { a e. ( SubDRing ` F ) | S C_ a } C_ { a e. ( SubDRing ` F ) | T C_ a } -> |^| { a e. ( SubDRing ` F ) | T C_ a } C_ |^| { a e. ( SubDRing ` F ) | S C_ a } ) |
|
| 12 | 10 11 | syl | |- ( ph -> |^| { a e. ( SubDRing ` F ) | T C_ a } C_ |^| { a e. ( SubDRing ` F ) | S C_ a } ) |
| 13 | 4 3 | sstrd | |- ( ph -> T C_ B ) |
| 14 | 1 2 13 | fldgenval | |- ( ph -> ( F fldGen T ) = |^| { a e. ( SubDRing ` F ) | T C_ a } ) |
| 15 | 1 2 3 | fldgenval | |- ( ph -> ( F fldGen S ) = |^| { a e. ( SubDRing ` F ) | S C_ a } ) |
| 16 | 12 14 15 | 3sstr4d | |- ( ph -> ( F fldGen T ) C_ ( F fldGen S ) ) |