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Description: Set of morphisms of the trivial category. (Contributed by Zhi Wang, 22-Oct-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | funcsetc1o.1 | |- .1. = ( SetCat ` 1o ) |
|
| Assertion | setc1ohomfval | |- { <. (/) , (/) , 1o >. } = ( Hom ` .1. ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | funcsetc1o.1 | |- .1. = ( SetCat ` 1o ) |
|
| 2 | df-ot | |- <. (/) , (/) , 1o >. = <. <. (/) , (/) >. , 1o >. |
|
| 3 | 2 | sneqi | |- { <. (/) , (/) , 1o >. } = { <. <. (/) , (/) >. , 1o >. } |
| 4 | 0ex | |- (/) e. _V |
|
| 5 | 1oex | |- 1o e. _V |
|
| 6 | df1o2 | |- 1o = { (/) } |
|
| 7 | 6 | fveq2i | |- ( SetCat ` 1o ) = ( SetCat ` { (/) } ) |
| 8 | 1 7 | eqtri | |- .1. = ( SetCat ` { (/) } ) |
| 9 | p0ex | |- { (/) } e. _V |
|
| 10 | 9 | a1i | |- ( T. -> { (/) } e. _V ) |
| 11 | eqid | |- ( Hom ` .1. ) = ( Hom ` .1. ) |
|
| 12 | 8 10 11 | setchomfval | |- ( T. -> ( Hom ` .1. ) = ( x e. { (/) } , y e. { (/) } |-> ( y ^m x ) ) ) |
| 13 | 12 | mptru | |- ( Hom ` .1. ) = ( x e. { (/) } , y e. { (/) } |-> ( y ^m x ) ) |
| 14 | oveq2 | |- ( x = (/) -> ( y ^m x ) = ( y ^m (/) ) ) |
|
| 15 | oveq1 | |- ( y = (/) -> ( y ^m (/) ) = ( (/) ^m (/) ) ) |
|
| 16 | 0map0sn0 | |- ( (/) ^m (/) ) = { (/) } |
|
| 17 | 16 6 | eqtr4i | |- ( (/) ^m (/) ) = 1o |
| 18 | 15 17 | eqtrdi | |- ( y = (/) -> ( y ^m (/) ) = 1o ) |
| 19 | 13 14 18 | mposn | |- ( ( (/) e. _V /\ (/) e. _V /\ 1o e. _V ) -> ( Hom ` .1. ) = { <. <. (/) , (/) >. , 1o >. } ) |
| 20 | 4 4 5 19 | mp3an | |- ( Hom ` .1. ) = { <. <. (/) , (/) >. , 1o >. } |
| 21 | 3 20 | eqtr4i | |- { <. (/) , (/) , 1o >. } = ( Hom ` .1. ) |