| Step | Hyp | Ref | Expression | 
						
							| 1 |  | dvhopadd.a | ⊢ 𝐴  =  ( 𝑓  ∈  ( 𝑇  ×  𝐸 ) ,  𝑔  ∈  ( 𝑇  ×  𝐸 )  ↦  〈 ( ( 1st  ‘ 𝑓 )  ∘  ( 1st  ‘ 𝑔 ) ) ,  ( ( 2nd  ‘ 𝑓 ) 𝑃 ( 2nd  ‘ 𝑔 ) ) 〉 ) | 
						
							| 2 |  | opelxpi | ⊢ ( ( 𝐹  ∈  𝑇  ∧  𝑈  ∈  𝐸 )  →  〈 𝐹 ,  𝑈 〉  ∈  ( 𝑇  ×  𝐸 ) ) | 
						
							| 3 |  | opelxpi | ⊢ ( ( 𝐺  ∈  𝑇  ∧  𝑉  ∈  𝐸 )  →  〈 𝐺 ,  𝑉 〉  ∈  ( 𝑇  ×  𝐸 ) ) | 
						
							| 4 | 1 | dvhvaddval | ⊢ ( ( 〈 𝐹 ,  𝑈 〉  ∈  ( 𝑇  ×  𝐸 )  ∧  〈 𝐺 ,  𝑉 〉  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 〈 𝐹 ,  𝑈 〉 𝐴 〈 𝐺 ,  𝑉 〉 )  =  〈 ( ( 1st  ‘ 〈 𝐹 ,  𝑈 〉 )  ∘  ( 1st  ‘ 〈 𝐺 ,  𝑉 〉 ) ) ,  ( ( 2nd  ‘ 〈 𝐹 ,  𝑈 〉 ) 𝑃 ( 2nd  ‘ 〈 𝐺 ,  𝑉 〉 ) ) 〉 ) | 
						
							| 5 | 2 3 4 | syl2an | ⊢ ( ( ( 𝐹  ∈  𝑇  ∧  𝑈  ∈  𝐸 )  ∧  ( 𝐺  ∈  𝑇  ∧  𝑉  ∈  𝐸 ) )  →  ( 〈 𝐹 ,  𝑈 〉 𝐴 〈 𝐺 ,  𝑉 〉 )  =  〈 ( ( 1st  ‘ 〈 𝐹 ,  𝑈 〉 )  ∘  ( 1st  ‘ 〈 𝐺 ,  𝑉 〉 ) ) ,  ( ( 2nd  ‘ 〈 𝐹 ,  𝑈 〉 ) 𝑃 ( 2nd  ‘ 〈 𝐺 ,  𝑉 〉 ) ) 〉 ) | 
						
							| 6 |  | op1stg | ⊢ ( ( 𝐹  ∈  𝑇  ∧  𝑈  ∈  𝐸 )  →  ( 1st  ‘ 〈 𝐹 ,  𝑈 〉 )  =  𝐹 ) | 
						
							| 7 | 6 | adantr | ⊢ ( ( ( 𝐹  ∈  𝑇  ∧  𝑈  ∈  𝐸 )  ∧  ( 𝐺  ∈  𝑇  ∧  𝑉  ∈  𝐸 ) )  →  ( 1st  ‘ 〈 𝐹 ,  𝑈 〉 )  =  𝐹 ) | 
						
							| 8 |  | op1stg | ⊢ ( ( 𝐺  ∈  𝑇  ∧  𝑉  ∈  𝐸 )  →  ( 1st  ‘ 〈 𝐺 ,  𝑉 〉 )  =  𝐺 ) | 
						
							| 9 | 8 | adantl | ⊢ ( ( ( 𝐹  ∈  𝑇  ∧  𝑈  ∈  𝐸 )  ∧  ( 𝐺  ∈  𝑇  ∧  𝑉  ∈  𝐸 ) )  →  ( 1st  ‘ 〈 𝐺 ,  𝑉 〉 )  =  𝐺 ) | 
						
							| 10 | 7 9 | coeq12d | ⊢ ( ( ( 𝐹  ∈  𝑇  ∧  𝑈  ∈  𝐸 )  ∧  ( 𝐺  ∈  𝑇  ∧  𝑉  ∈  𝐸 ) )  →  ( ( 1st  ‘ 〈 𝐹 ,  𝑈 〉 )  ∘  ( 1st  ‘ 〈 𝐺 ,  𝑉 〉 ) )  =  ( 𝐹  ∘  𝐺 ) ) | 
						
							| 11 |  | op2ndg | ⊢ ( ( 𝐹  ∈  𝑇  ∧  𝑈  ∈  𝐸 )  →  ( 2nd  ‘ 〈 𝐹 ,  𝑈 〉 )  =  𝑈 ) | 
						
							| 12 |  | op2ndg | ⊢ ( ( 𝐺  ∈  𝑇  ∧  𝑉  ∈  𝐸 )  →  ( 2nd  ‘ 〈 𝐺 ,  𝑉 〉 )  =  𝑉 ) | 
						
							| 13 | 11 12 | oveqan12d | ⊢ ( ( ( 𝐹  ∈  𝑇  ∧  𝑈  ∈  𝐸 )  ∧  ( 𝐺  ∈  𝑇  ∧  𝑉  ∈  𝐸 ) )  →  ( ( 2nd  ‘ 〈 𝐹 ,  𝑈 〉 ) 𝑃 ( 2nd  ‘ 〈 𝐺 ,  𝑉 〉 ) )  =  ( 𝑈 𝑃 𝑉 ) ) | 
						
							| 14 | 10 13 | opeq12d | ⊢ ( ( ( 𝐹  ∈  𝑇  ∧  𝑈  ∈  𝐸 )  ∧  ( 𝐺  ∈  𝑇  ∧  𝑉  ∈  𝐸 ) )  →  〈 ( ( 1st  ‘ 〈 𝐹 ,  𝑈 〉 )  ∘  ( 1st  ‘ 〈 𝐺 ,  𝑉 〉 ) ) ,  ( ( 2nd  ‘ 〈 𝐹 ,  𝑈 〉 ) 𝑃 ( 2nd  ‘ 〈 𝐺 ,  𝑉 〉 ) ) 〉  =  〈 ( 𝐹  ∘  𝐺 ) ,  ( 𝑈 𝑃 𝑉 ) 〉 ) | 
						
							| 15 | 5 14 | eqtrd | ⊢ ( ( ( 𝐹  ∈  𝑇  ∧  𝑈  ∈  𝐸 )  ∧  ( 𝐺  ∈  𝑇  ∧  𝑉  ∈  𝐸 ) )  →  ( 〈 𝐹 ,  𝑈 〉 𝐴 〈 𝐺 ,  𝑉 〉 )  =  〈 ( 𝐹  ∘  𝐺 ) ,  ( 𝑈 𝑃 𝑉 ) 〉 ) |