| Step | Hyp | Ref | Expression | 
						
							| 1 |  | rngcbasALTV.c | ⊢ 𝐶  =  ( RngCatALTV ‘ 𝑈 ) | 
						
							| 2 |  | rngcbasALTV.b | ⊢ 𝐵  =  ( Base ‘ 𝐶 ) | 
						
							| 3 |  | rngcbasALTV.u | ⊢ ( 𝜑  →  𝑈  ∈  𝑉 ) | 
						
							| 4 |  | rngccofvalALTV.o | ⊢  ·   =  ( comp ‘ 𝐶 ) | 
						
							| 5 | 1 2 3 | rngcbasALTV | ⊢ ( 𝜑  →  𝐵  =  ( 𝑈  ∩  Rng ) ) | 
						
							| 6 |  | eqid | ⊢ ( Hom  ‘ 𝐶 )  =  ( Hom  ‘ 𝐶 ) | 
						
							| 7 | 1 2 3 6 | rngchomfvalALTV | ⊢ ( 𝜑  →  ( Hom  ‘ 𝐶 )  =  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( 𝑥  RngHom  𝑦 ) ) ) | 
						
							| 8 |  | eqidd | ⊢ ( 𝜑  →  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) )  =  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) ) ) | 
						
							| 9 | 1 3 5 7 8 | rngcvalALTV | ⊢ ( 𝜑  →  𝐶  =  { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( Hom  ‘ 𝐶 ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) ) 〉 } ) | 
						
							| 10 | 9 | fveq2d | ⊢ ( 𝜑  →  ( comp ‘ 𝐶 )  =  ( comp ‘ { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( Hom  ‘ 𝐶 ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) ) 〉 } ) ) | 
						
							| 11 | 2 | fvexi | ⊢ 𝐵  ∈  V | 
						
							| 12 |  | sqxpexg | ⊢ ( 𝐵  ∈  V  →  ( 𝐵  ×  𝐵 )  ∈  V ) | 
						
							| 13 | 11 12 | ax-mp | ⊢ ( 𝐵  ×  𝐵 )  ∈  V | 
						
							| 14 | 13 11 | mpoex | ⊢ ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) )  ∈  V | 
						
							| 15 |  | catstr | ⊢ { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( Hom  ‘ 𝐶 ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) ) 〉 }  Struct  〈 1 ,  ; 1 5 〉 | 
						
							| 16 |  | ccoid | ⊢ comp  =  Slot  ( comp ‘ ndx ) | 
						
							| 17 |  | snsstp3 | ⊢ { 〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) ) 〉 }  ⊆  { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( Hom  ‘ 𝐶 ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) ) 〉 } | 
						
							| 18 | 15 16 17 | strfv | ⊢ ( ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) )  ∈  V  →  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) )  =  ( comp ‘ { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( Hom  ‘ 𝐶 ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) ) 〉 } ) ) | 
						
							| 19 | 14 18 | ax-mp | ⊢ ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) )  =  ( comp ‘ { 〈 ( Base ‘ ndx ) ,  𝐵 〉 ,  〈 ( Hom  ‘ ndx ) ,  ( Hom  ‘ 𝐶 ) 〉 ,  〈 ( comp ‘ ndx ) ,  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) ) 〉 } ) | 
						
							| 20 | 10 4 19 | 3eqtr4g | ⊢ ( 𝜑  →   ·   =  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) ) ) |