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Description: Definition of the category Ring, relativized to a subset u . See also the note in Lang p. 91, and the item Rng in Adamek p. 478. This is the category of all unital rings in u and homomorphisms between these rings. Generally, we will take u to be a weak universe or Grothendieck universe, because these sets have closure properties as good as the real thing. (Contributed by AV, 13-Feb-2020) (Revised by AV, 8-Mar-2020)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-ringc | |- RingCat = ( u e. _V |-> ( ( ExtStrCat ` u ) |`cat ( RingHom |` ( ( u i^i Ring ) X. ( u i^i Ring ) ) ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | cringc | |- RingCat |
|
| 1 | vu | |- u |
|
| 2 | cvv | |- _V |
|
| 3 | cestrc | |- ExtStrCat |
|
| 4 | 1 | cv | |- u |
| 5 | 4 3 | cfv | |- ( ExtStrCat ` u ) |
| 6 | cresc | |- |`cat |
|
| 7 | crh | |- RingHom |
|
| 8 | crg | |- Ring |
|
| 9 | 4 8 | cin | |- ( u i^i Ring ) |
| 10 | 9 9 | cxp | |- ( ( u i^i Ring ) X. ( u i^i Ring ) ) |
| 11 | 7 10 | cres | |- ( RingHom |` ( ( u i^i Ring ) X. ( u i^i Ring ) ) ) |
| 12 | 5 11 6 | co | |- ( ( ExtStrCat ` u ) |`cat ( RingHom |` ( ( u i^i Ring ) X. ( u i^i Ring ) ) ) ) |
| 13 | 1 2 12 | cmpt | |- ( u e. _V |-> ( ( ExtStrCat ` u ) |`cat ( RingHom |` ( ( u i^i Ring ) X. ( u i^i Ring ) ) ) ) ) |
| 14 | 0 13 | wceq | |- RingCat = ( u e. _V |-> ( ( ExtStrCat ` u ) |`cat ( RingHom |` ( ( u i^i Ring ) X. ( u i^i Ring ) ) ) ) ) |