| Step | Hyp | Ref | Expression | 
						
							| 1 |  | rngcbasALTV.c |  |-  C = ( RngCatALTV ` U ) | 
						
							| 2 |  | rngcbasALTV.b |  |-  B = ( Base ` C ) | 
						
							| 3 |  | rngcbasALTV.u |  |-  ( ph -> U e. V ) | 
						
							| 4 |  | eqidd |  |-  ( ph -> ( U i^i Rng ) = ( U i^i Rng ) ) | 
						
							| 5 |  | eqidd |  |-  ( ph -> ( x e. ( U i^i Rng ) , y e. ( U i^i Rng ) |-> ( x RngHom y ) ) = ( x e. ( U i^i Rng ) , y e. ( U i^i Rng ) |-> ( x RngHom y ) ) ) | 
						
							| 6 |  | eqidd |  |-  ( ph -> ( v e. ( ( U i^i Rng ) X. ( U i^i Rng ) ) , z e. ( U i^i Rng ) |-> ( f e. ( ( 2nd ` v ) RngHom z ) , g e. ( ( 1st ` v ) RngHom ( 2nd ` v ) ) |-> ( f o. g ) ) ) = ( v e. ( ( U i^i Rng ) X. ( U i^i Rng ) ) , z e. ( U i^i Rng ) |-> ( f e. ( ( 2nd ` v ) RngHom z ) , g e. ( ( 1st ` v ) RngHom ( 2nd ` v ) ) |-> ( f o. g ) ) ) ) | 
						
							| 7 | 1 3 4 5 6 | rngcvalALTV |  |-  ( ph -> C = { <. ( Base ` ndx ) , ( U i^i Rng ) >. , <. ( Hom ` ndx ) , ( x e. ( U i^i Rng ) , y e. ( U i^i Rng ) |-> ( x RngHom y ) ) >. , <. ( comp ` ndx ) , ( v e. ( ( U i^i Rng ) X. ( U i^i Rng ) ) , z e. ( U i^i Rng ) |-> ( f e. ( ( 2nd ` v ) RngHom z ) , g e. ( ( 1st ` v ) RngHom ( 2nd ` v ) ) |-> ( f o. g ) ) ) >. } ) | 
						
							| 8 |  | catstr |  |-  { <. ( Base ` ndx ) , ( U i^i Rng ) >. , <. ( Hom ` ndx ) , ( x e. ( U i^i Rng ) , y e. ( U i^i Rng ) |-> ( x RngHom y ) ) >. , <. ( comp ` ndx ) , ( v e. ( ( U i^i Rng ) X. ( U i^i Rng ) ) , z e. ( U i^i Rng ) |-> ( f e. ( ( 2nd ` v ) RngHom z ) , g e. ( ( 1st ` v ) RngHom ( 2nd ` v ) ) |-> ( f o. g ) ) ) >. } Struct <. 1 , ; 1 5 >. | 
						
							| 9 |  | baseid |  |-  Base = Slot ( Base ` ndx ) | 
						
							| 10 |  | snsstp1 |  |-  { <. ( Base ` ndx ) , ( U i^i Rng ) >. } C_ { <. ( Base ` ndx ) , ( U i^i Rng ) >. , <. ( Hom ` ndx ) , ( x e. ( U i^i Rng ) , y e. ( U i^i Rng ) |-> ( x RngHom y ) ) >. , <. ( comp ` ndx ) , ( v e. ( ( U i^i Rng ) X. ( U i^i Rng ) ) , z e. ( U i^i Rng ) |-> ( f e. ( ( 2nd ` v ) RngHom z ) , g e. ( ( 1st ` v ) RngHom ( 2nd ` v ) ) |-> ( f o. g ) ) ) >. } | 
						
							| 11 |  | inex1g |  |-  ( U e. V -> ( U i^i Rng ) e. _V ) | 
						
							| 12 | 3 11 | syl |  |-  ( ph -> ( U i^i Rng ) e. _V ) | 
						
							| 13 | 7 8 9 10 12 2 | strfv3 |  |-  ( ph -> B = ( U i^i Rng ) ) |