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Description: Value of natural transformations for a terminal category. (Contributed by Zhi Wang, 21-Oct-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | termcnatval.c | |- ( ph -> C e. TermCat ) |
|
| termcnatval.n | |- N = ( C Nat D ) |
||
| termcnatval.a | |- ( ph -> A e. ( F N G ) ) |
||
| termcnatval.b | |- B = ( Base ` C ) |
||
| termcnatval.x | |- ( ph -> X e. B ) |
||
| termcnatval.r | |- R = ( A ` X ) |
||
| Assertion | termcnatval | |- ( ph -> A = { <. X , R >. } ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | termcnatval.c | |- ( ph -> C e. TermCat ) |
|
| 2 | termcnatval.n | |- N = ( C Nat D ) |
|
| 3 | termcnatval.a | |- ( ph -> A e. ( F N G ) ) |
|
| 4 | termcnatval.b | |- B = ( Base ` C ) |
|
| 5 | termcnatval.x | |- ( ph -> X e. B ) |
|
| 6 | termcnatval.r | |- R = ( A ` X ) |
|
| 7 | 2 3 | nat1st2nd | |- ( ph -> A e. ( <. ( 1st ` F ) , ( 2nd ` F ) >. N <. ( 1st ` G ) , ( 2nd ` G ) >. ) ) |
| 8 | 2 7 4 | natfn | |- ( ph -> A Fn B ) |
| 9 | 1 4 5 | termcbas2 | |- ( ph -> B = { X } ) |
| 10 | 9 | fneq2d | |- ( ph -> ( A Fn B <-> A Fn { X } ) ) |
| 11 | 8 10 | mpbid | |- ( ph -> A Fn { X } ) |
| 12 | fnsnbg | |- ( X e. B -> ( A Fn { X } <-> A = { <. X , ( A ` X ) >. } ) ) |
|
| 13 | 5 12 | syl | |- ( ph -> ( A Fn { X } <-> A = { <. X , ( A ` X ) >. } ) ) |
| 14 | 11 13 | mpbid | |- ( ph -> A = { <. X , ( A ` X ) >. } ) |
| 15 | 6 | opeq2i | |- <. X , R >. = <. X , ( A ` X ) >. |
| 16 | 15 | sneqi | |- { <. X , R >. } = { <. X , ( A ` X ) >. } |
| 17 | 14 16 | eqtr4di | |- ( ph -> A = { <. X , R >. } ) |