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Description: Isomorphism implies the left side is an object. (Contributed by AV, 5-Apr-2020)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | ciclcl | |- ( ( C e. Cat /\ R ( ~=c ` C ) S ) -> R e. ( Base ` C ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | cicfval | |- ( C e. Cat -> ( ~=c ` C ) = ( ( Iso ` C ) supp (/) ) ) |
|
| 2 | 1 | breqd | |- ( C e. Cat -> ( R ( ~=c ` C ) S <-> R ( ( Iso ` C ) supp (/) ) S ) ) |
| 3 | isofn | |- ( C e. Cat -> ( Iso ` C ) Fn ( ( Base ` C ) X. ( Base ` C ) ) ) |
|
| 4 | fvexd | |- ( C e. Cat -> ( Iso ` C ) e. _V ) |
|
| 5 | 0ex | |- (/) e. _V |
|
| 6 | 5 | a1i | |- ( C e. Cat -> (/) e. _V ) |
| 7 | df-br | |- ( R ( ( Iso ` C ) supp (/) ) S <-> <. R , S >. e. ( ( Iso ` C ) supp (/) ) ) |
|
| 8 | elsuppfng | |- ( ( ( Iso ` C ) Fn ( ( Base ` C ) X. ( Base ` C ) ) /\ ( Iso ` C ) e. _V /\ (/) e. _V ) -> ( <. R , S >. e. ( ( Iso ` C ) supp (/) ) <-> ( <. R , S >. e. ( ( Base ` C ) X. ( Base ` C ) ) /\ ( ( Iso ` C ) ` <. R , S >. ) =/= (/) ) ) ) |
|
| 9 | 7 8 | bitrid | |- ( ( ( Iso ` C ) Fn ( ( Base ` C ) X. ( Base ` C ) ) /\ ( Iso ` C ) e. _V /\ (/) e. _V ) -> ( R ( ( Iso ` C ) supp (/) ) S <-> ( <. R , S >. e. ( ( Base ` C ) X. ( Base ` C ) ) /\ ( ( Iso ` C ) ` <. R , S >. ) =/= (/) ) ) ) |
| 10 | 3 4 6 9 | syl3anc | |- ( C e. Cat -> ( R ( ( Iso ` C ) supp (/) ) S <-> ( <. R , S >. e. ( ( Base ` C ) X. ( Base ` C ) ) /\ ( ( Iso ` C ) ` <. R , S >. ) =/= (/) ) ) ) |
| 11 | opelxp1 | |- ( <. R , S >. e. ( ( Base ` C ) X. ( Base ` C ) ) -> R e. ( Base ` C ) ) |
|
| 12 | 11 | adantr | |- ( ( <. R , S >. e. ( ( Base ` C ) X. ( Base ` C ) ) /\ ( ( Iso ` C ) ` <. R , S >. ) =/= (/) ) -> R e. ( Base ` C ) ) |
| 13 | 10 12 | biimtrdi | |- ( C e. Cat -> ( R ( ( Iso ` C ) supp (/) ) S -> R e. ( Base ` C ) ) ) |
| 14 | 2 13 | sylbid | |- ( C e. Cat -> ( R ( ~=c ` C ) S -> R e. ( Base ` C ) ) ) |
| 15 | 14 | imp | |- ( ( C e. Cat /\ R ( ~=c ` C ) S ) -> R e. ( Base ` C ) ) |