| Step | Hyp | Ref | Expression | 
						
							| 1 |  | rngcbasALTV.c | ⊢ 𝐶  =  ( RngCatALTV ‘ 𝑈 ) | 
						
							| 2 |  | rngcbasALTV.b | ⊢ 𝐵  =  ( Base ‘ 𝐶 ) | 
						
							| 3 |  | rngcbasALTV.u | ⊢ ( 𝜑  →  𝑈  ∈  𝑉 ) | 
						
							| 4 |  | rngchomfvalALTV.h | ⊢ 𝐻  =  ( Hom  ‘ 𝐶 ) | 
						
							| 5 | 1 2 3 | rngcbasALTV | ⊢ ( 𝜑  →  𝐵  =  ( 𝑈  ∩  Rng ) ) | 
						
							| 6 |  | eqidd | ⊢ ( 𝜑  →  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) )  =  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) ) ) | 
						
							| 7 |  | eqidd | ⊢ ( 𝜑  →  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑓  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑔  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑓  ∘  𝑔 ) ) )  =  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑓  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑔  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑓  ∘  𝑔 ) ) ) ) | 
						
							| 8 | 1 3 5 6 7 | rngcvalALTV | ⊢ ( 𝜑  →  𝐶  =  { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑓  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑔  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑓  ∘  𝑔 ) ) ) 〉 } ) | 
						
							| 9 | 8 | fveq2d | ⊢ ( 𝜑  →  ( Hom  ‘ 𝐶 )  =  ( Hom  ‘ { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑓  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑔  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑓  ∘  𝑔 ) ) ) 〉 } ) ) | 
						
							| 10 | 4 9 | eqtrid | ⊢ ( 𝜑  →  𝐻  =  ( Hom  ‘ { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑓  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑔  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑓  ∘  𝑔 ) ) ) 〉 } ) ) | 
						
							| 11 | 2 | fvexi | ⊢ 𝐵  ∈  V | 
						
							| 12 | 11 11 | mpoex | ⊢ ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) )  ∈  V | 
						
							| 13 |  | catstr | ⊢ { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑓  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑔  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑓  ∘  𝑔 ) ) ) 〉 }  Struct  〈 1 ,  ; 1 5 〉 | 
						
							| 14 |  | homid | ⊢ Hom   =  Slot  ( Hom  ‘ ndx ) | 
						
							| 15 |  | snsstp2 | ⊢ { 〈 ( Hom  ‘ ndx ) ,  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) ) 〉 }  ⊆  { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑓  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑔  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑓  ∘  𝑔 ) ) ) 〉 } | 
						
							| 16 | 13 14 15 | strfv | ⊢ ( ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) )  ∈  V  →  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) )  =  ( Hom  ‘ { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑓  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑔  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑓  ∘  𝑔 ) ) ) 〉 } ) ) | 
						
							| 17 | 12 16 | mp1i | ⊢ ( 𝜑  →  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) )  =  ( Hom  ‘ { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑓  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑔  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑓  ∘  𝑔 ) ) ) 〉 } ) ) | 
						
							| 18 | 10 17 | eqtr4d | ⊢ ( 𝜑  →  𝐻  =  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) ) ) |