| Step | Hyp | Ref | Expression | 
						
							| 1 |  | rhmsubcsetc.c |  |-  C = ( ExtStrCat ` U ) | 
						
							| 2 |  | rhmsubcsetc.u |  |-  ( ph -> U e. V ) | 
						
							| 3 |  | rhmsubcsetc.b |  |-  ( ph -> B = ( Ring i^i U ) ) | 
						
							| 4 |  | rhmsubcsetc.h |  |-  ( ph -> H = ( RingHom |` ( B X. B ) ) ) | 
						
							| 5 | 3 | eleq2d |  |-  ( ph -> ( x e. B <-> x e. ( Ring i^i U ) ) ) | 
						
							| 6 |  | elin |  |-  ( x e. ( Ring i^i U ) <-> ( x e. Ring /\ x e. U ) ) | 
						
							| 7 | 6 | simplbi |  |-  ( x e. ( Ring i^i U ) -> x e. Ring ) | 
						
							| 8 | 5 7 | biimtrdi |  |-  ( ph -> ( x e. B -> x e. Ring ) ) | 
						
							| 9 | 8 | imp |  |-  ( ( ph /\ x e. B ) -> x e. Ring ) | 
						
							| 10 |  | eqid |  |-  ( Base ` x ) = ( Base ` x ) | 
						
							| 11 | 10 | idrhm |  |-  ( x e. Ring -> ( _I |` ( Base ` x ) ) e. ( x RingHom x ) ) | 
						
							| 12 | 9 11 | syl |  |-  ( ( ph /\ x e. B ) -> ( _I |` ( Base ` x ) ) e. ( x RingHom x ) ) | 
						
							| 13 |  | eqid |  |-  ( Id ` C ) = ( Id ` C ) | 
						
							| 14 | 2 | adantr |  |-  ( ( ph /\ x e. B ) -> U e. V ) | 
						
							| 15 | 6 | simprbi |  |-  ( x e. ( Ring i^i U ) -> x e. U ) | 
						
							| 16 | 5 15 | biimtrdi |  |-  ( ph -> ( x e. B -> x e. U ) ) | 
						
							| 17 | 16 | imp |  |-  ( ( ph /\ x e. B ) -> x e. U ) | 
						
							| 18 | 1 13 14 17 | estrcid |  |-  ( ( ph /\ x e. B ) -> ( ( Id ` C ) ` x ) = ( _I |` ( Base ` x ) ) ) | 
						
							| 19 | 4 | oveqdr |  |-  ( ( ph /\ x e. B ) -> ( x H x ) = ( x ( RingHom |` ( B X. B ) ) x ) ) | 
						
							| 20 |  | eqid |  |-  ( RingCat ` U ) = ( RingCat ` U ) | 
						
							| 21 |  | eqid |  |-  ( Base ` ( RingCat ` U ) ) = ( Base ` ( RingCat ` U ) ) | 
						
							| 22 |  | eqid |  |-  ( Hom ` ( RingCat ` U ) ) = ( Hom ` ( RingCat ` U ) ) | 
						
							| 23 | 20 21 2 22 | ringchomfval |  |-  ( ph -> ( Hom ` ( RingCat ` U ) ) = ( RingHom |` ( ( Base ` ( RingCat ` U ) ) X. ( Base ` ( RingCat ` U ) ) ) ) ) | 
						
							| 24 | 20 21 2 | ringcbas |  |-  ( ph -> ( Base ` ( RingCat ` U ) ) = ( U i^i Ring ) ) | 
						
							| 25 |  | incom |  |-  ( Ring i^i U ) = ( U i^i Ring ) | 
						
							| 26 | 3 25 | eqtrdi |  |-  ( ph -> B = ( U i^i Ring ) ) | 
						
							| 27 | 26 | eqcomd |  |-  ( ph -> ( U i^i Ring ) = B ) | 
						
							| 28 | 24 27 | eqtrd |  |-  ( ph -> ( Base ` ( RingCat ` U ) ) = B ) | 
						
							| 29 | 28 | sqxpeqd |  |-  ( ph -> ( ( Base ` ( RingCat ` U ) ) X. ( Base ` ( RingCat ` U ) ) ) = ( B X. B ) ) | 
						
							| 30 | 29 | reseq2d |  |-  ( ph -> ( RingHom |` ( ( Base ` ( RingCat ` U ) ) X. ( Base ` ( RingCat ` U ) ) ) ) = ( RingHom |` ( B X. B ) ) ) | 
						
							| 31 | 23 30 | eqtrd |  |-  ( ph -> ( Hom ` ( RingCat ` U ) ) = ( RingHom |` ( B X. B ) ) ) | 
						
							| 32 | 31 | adantr |  |-  ( ( ph /\ x e. B ) -> ( Hom ` ( RingCat ` U ) ) = ( RingHom |` ( B X. B ) ) ) | 
						
							| 33 | 32 | eqcomd |  |-  ( ( ph /\ x e. B ) -> ( RingHom |` ( B X. B ) ) = ( Hom ` ( RingCat ` U ) ) ) | 
						
							| 34 | 33 | oveqd |  |-  ( ( ph /\ x e. B ) -> ( x ( RingHom |` ( B X. B ) ) x ) = ( x ( Hom ` ( RingCat ` U ) ) x ) ) | 
						
							| 35 | 26 | eleq2d |  |-  ( ph -> ( x e. B <-> x e. ( U i^i Ring ) ) ) | 
						
							| 36 | 35 | biimpa |  |-  ( ( ph /\ x e. B ) -> x e. ( U i^i Ring ) ) | 
						
							| 37 | 24 | adantr |  |-  ( ( ph /\ x e. B ) -> ( Base ` ( RingCat ` U ) ) = ( U i^i Ring ) ) | 
						
							| 38 | 36 37 | eleqtrrd |  |-  ( ( ph /\ x e. B ) -> x e. ( Base ` ( RingCat ` U ) ) ) | 
						
							| 39 | 20 21 14 22 38 38 | ringchom |  |-  ( ( ph /\ x e. B ) -> ( x ( Hom ` ( RingCat ` U ) ) x ) = ( x RingHom x ) ) | 
						
							| 40 | 19 34 39 | 3eqtrd |  |-  ( ( ph /\ x e. B ) -> ( x H x ) = ( x RingHom x ) ) | 
						
							| 41 | 12 18 40 | 3eltr4d |  |-  ( ( ph /\ x e. B ) -> ( ( Id ` C ) ` x ) e. ( x H x ) ) |