| 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 |  | rngccoALTV.x | ⊢ ( 𝜑  →  𝑋  ∈  𝐵 ) | 
						
							| 6 |  | rngccoALTV.y | ⊢ ( 𝜑  →  𝑌  ∈  𝐵 ) | 
						
							| 7 |  | rngccoALTV.z | ⊢ ( 𝜑  →  𝑍  ∈  𝐵 ) | 
						
							| 8 |  | rngccoALTV.f | ⊢ ( 𝜑  →  𝐹  ∈  ( 𝑋  RngHom  𝑌 ) ) | 
						
							| 9 |  | rngccoALTV.g | ⊢ ( 𝜑  →  𝐺  ∈  ( 𝑌  RngHom  𝑍 ) ) | 
						
							| 10 | 1 2 3 4 | rngccofvalALTV | ⊢ ( 𝜑  →   ·   =  ( 𝑣  ∈  ( 𝐵  ×  𝐵 ) ,  𝑧  ∈  𝐵  ↦  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) ) ) ) | 
						
							| 11 |  | simprl | ⊢ ( ( 𝜑  ∧  ( 𝑣  =  〈 𝑋 ,  𝑌 〉  ∧  𝑧  =  𝑍 ) )  →  𝑣  =  〈 𝑋 ,  𝑌 〉 ) | 
						
							| 12 | 11 | fveq2d | ⊢ ( ( 𝜑  ∧  ( 𝑣  =  〈 𝑋 ,  𝑌 〉  ∧  𝑧  =  𝑍 ) )  →  ( 2nd  ‘ 𝑣 )  =  ( 2nd  ‘ 〈 𝑋 ,  𝑌 〉 ) ) | 
						
							| 13 |  | op2ndg | ⊢ ( ( 𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 )  →  ( 2nd  ‘ 〈 𝑋 ,  𝑌 〉 )  =  𝑌 ) | 
						
							| 14 | 5 6 13 | syl2anc | ⊢ ( 𝜑  →  ( 2nd  ‘ 〈 𝑋 ,  𝑌 〉 )  =  𝑌 ) | 
						
							| 15 | 14 | adantr | ⊢ ( ( 𝜑  ∧  ( 𝑣  =  〈 𝑋 ,  𝑌 〉  ∧  𝑧  =  𝑍 ) )  →  ( 2nd  ‘ 〈 𝑋 ,  𝑌 〉 )  =  𝑌 ) | 
						
							| 16 | 12 15 | eqtrd | ⊢ ( ( 𝜑  ∧  ( 𝑣  =  〈 𝑋 ,  𝑌 〉  ∧  𝑧  =  𝑍 ) )  →  ( 2nd  ‘ 𝑣 )  =  𝑌 ) | 
						
							| 17 |  | simprr | ⊢ ( ( 𝜑  ∧  ( 𝑣  =  〈 𝑋 ,  𝑌 〉  ∧  𝑧  =  𝑍 ) )  →  𝑧  =  𝑍 ) | 
						
							| 18 | 16 17 | oveq12d | ⊢ ( ( 𝜑  ∧  ( 𝑣  =  〈 𝑋 ,  𝑌 〉  ∧  𝑧  =  𝑍 ) )  →  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 )  =  ( 𝑌  RngHom  𝑍 ) ) | 
						
							| 19 | 11 | fveq2d | ⊢ ( ( 𝜑  ∧  ( 𝑣  =  〈 𝑋 ,  𝑌 〉  ∧  𝑧  =  𝑍 ) )  →  ( 1st  ‘ 𝑣 )  =  ( 1st  ‘ 〈 𝑋 ,  𝑌 〉 ) ) | 
						
							| 20 |  | op1stg | ⊢ ( ( 𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 )  →  ( 1st  ‘ 〈 𝑋 ,  𝑌 〉 )  =  𝑋 ) | 
						
							| 21 | 5 6 20 | syl2anc | ⊢ ( 𝜑  →  ( 1st  ‘ 〈 𝑋 ,  𝑌 〉 )  =  𝑋 ) | 
						
							| 22 | 21 | adantr | ⊢ ( ( 𝜑  ∧  ( 𝑣  =  〈 𝑋 ,  𝑌 〉  ∧  𝑧  =  𝑍 ) )  →  ( 1st  ‘ 〈 𝑋 ,  𝑌 〉 )  =  𝑋 ) | 
						
							| 23 | 19 22 | eqtrd | ⊢ ( ( 𝜑  ∧  ( 𝑣  =  〈 𝑋 ,  𝑌 〉  ∧  𝑧  =  𝑍 ) )  →  ( 1st  ‘ 𝑣 )  =  𝑋 ) | 
						
							| 24 | 23 16 | oveq12d | ⊢ ( ( 𝜑  ∧  ( 𝑣  =  〈 𝑋 ,  𝑌 〉  ∧  𝑧  =  𝑍 ) )  →  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  =  ( 𝑋  RngHom  𝑌 ) ) | 
						
							| 25 |  | eqidd | ⊢ ( ( 𝜑  ∧  ( 𝑣  =  〈 𝑋 ,  𝑌 〉  ∧  𝑧  =  𝑍 ) )  →  ( 𝑔  ∘  𝑓 )  =  ( 𝑔  ∘  𝑓 ) ) | 
						
							| 26 | 18 24 25 | mpoeq123dv | ⊢ ( ( 𝜑  ∧  ( 𝑣  =  〈 𝑋 ,  𝑌 〉  ∧  𝑧  =  𝑍 ) )  →  ( 𝑔  ∈  ( ( 2nd  ‘ 𝑣 )  RngHom  𝑧 ) ,  𝑓  ∈  ( ( 1st  ‘ 𝑣 )  RngHom  ( 2nd  ‘ 𝑣 ) )  ↦  ( 𝑔  ∘  𝑓 ) )  =  ( 𝑔  ∈  ( 𝑌  RngHom  𝑍 ) ,  𝑓  ∈  ( 𝑋  RngHom  𝑌 )  ↦  ( 𝑔  ∘  𝑓 ) ) ) | 
						
							| 27 |  | opelxpi | ⊢ ( ( 𝑋  ∈  𝐵  ∧  𝑌  ∈  𝐵 )  →  〈 𝑋 ,  𝑌 〉  ∈  ( 𝐵  ×  𝐵 ) ) | 
						
							| 28 | 5 6 27 | syl2anc | ⊢ ( 𝜑  →  〈 𝑋 ,  𝑌 〉  ∈  ( 𝐵  ×  𝐵 ) ) | 
						
							| 29 |  | ovex | ⊢ ( 𝑌  RngHom  𝑍 )  ∈  V | 
						
							| 30 |  | ovex | ⊢ ( 𝑋  RngHom  𝑌 )  ∈  V | 
						
							| 31 | 29 30 | mpoex | ⊢ ( 𝑔  ∈  ( 𝑌  RngHom  𝑍 ) ,  𝑓  ∈  ( 𝑋  RngHom  𝑌 )  ↦  ( 𝑔  ∘  𝑓 ) )  ∈  V | 
						
							| 32 | 31 | a1i | ⊢ ( 𝜑  →  ( 𝑔  ∈  ( 𝑌  RngHom  𝑍 ) ,  𝑓  ∈  ( 𝑋  RngHom  𝑌 )  ↦  ( 𝑔  ∘  𝑓 ) )  ∈  V ) | 
						
							| 33 | 10 26 28 7 32 | ovmpod | ⊢ ( 𝜑  →  ( 〈 𝑋 ,  𝑌 〉  ·  𝑍 )  =  ( 𝑔  ∈  ( 𝑌  RngHom  𝑍 ) ,  𝑓  ∈  ( 𝑋  RngHom  𝑌 )  ↦  ( 𝑔  ∘  𝑓 ) ) ) | 
						
							| 34 |  | simprl | ⊢ ( ( 𝜑  ∧  ( 𝑔  =  𝐺  ∧  𝑓  =  𝐹 ) )  →  𝑔  =  𝐺 ) | 
						
							| 35 |  | simprr | ⊢ ( ( 𝜑  ∧  ( 𝑔  =  𝐺  ∧  𝑓  =  𝐹 ) )  →  𝑓  =  𝐹 ) | 
						
							| 36 | 34 35 | coeq12d | ⊢ ( ( 𝜑  ∧  ( 𝑔  =  𝐺  ∧  𝑓  =  𝐹 ) )  →  ( 𝑔  ∘  𝑓 )  =  ( 𝐺  ∘  𝐹 ) ) | 
						
							| 37 |  | coexg | ⊢ ( ( 𝐺  ∈  ( 𝑌  RngHom  𝑍 )  ∧  𝐹  ∈  ( 𝑋  RngHom  𝑌 ) )  →  ( 𝐺  ∘  𝐹 )  ∈  V ) | 
						
							| 38 | 9 8 37 | syl2anc | ⊢ ( 𝜑  →  ( 𝐺  ∘  𝐹 )  ∈  V ) | 
						
							| 39 | 33 36 9 8 38 | ovmpod | ⊢ ( 𝜑  →  ( 𝐺 ( 〈 𝑋 ,  𝑌 〉  ·  𝑍 ) 𝐹 )  =  ( 𝐺  ∘  𝐹 ) ) |