| Step | Hyp | Ref | Expression | 
						
							| 1 |  | dvhopadd.a |  |-  A = ( f e. ( T X. E ) , g e. ( T X. E ) |-> <. ( ( 1st ` f ) o. ( 1st ` g ) ) , ( ( 2nd ` f ) P ( 2nd ` g ) ) >. ) | 
						
							| 2 |  | opelxpi |  |-  ( ( F e. T /\ U e. E ) -> <. F , U >. e. ( T X. E ) ) | 
						
							| 3 |  | opelxpi |  |-  ( ( G e. T /\ V e. E ) -> <. G , V >. e. ( T X. E ) ) | 
						
							| 4 | 1 | dvhvaddval |  |-  ( ( <. F , U >. e. ( T X. E ) /\ <. G , V >. e. ( T X. E ) ) -> ( <. F , U >. A <. G , V >. ) = <. ( ( 1st ` <. F , U >. ) o. ( 1st ` <. G , V >. ) ) , ( ( 2nd ` <. F , U >. ) P ( 2nd ` <. G , V >. ) ) >. ) | 
						
							| 5 | 2 3 4 | syl2an |  |-  ( ( ( F e. T /\ U e. E ) /\ ( G e. T /\ V e. E ) ) -> ( <. F , U >. A <. G , V >. ) = <. ( ( 1st ` <. F , U >. ) o. ( 1st ` <. G , V >. ) ) , ( ( 2nd ` <. F , U >. ) P ( 2nd ` <. G , V >. ) ) >. ) | 
						
							| 6 |  | op1stg |  |-  ( ( F e. T /\ U e. E ) -> ( 1st ` <. F , U >. ) = F ) | 
						
							| 7 | 6 | adantr |  |-  ( ( ( F e. T /\ U e. E ) /\ ( G e. T /\ V e. E ) ) -> ( 1st ` <. F , U >. ) = F ) | 
						
							| 8 |  | op1stg |  |-  ( ( G e. T /\ V e. E ) -> ( 1st ` <. G , V >. ) = G ) | 
						
							| 9 | 8 | adantl |  |-  ( ( ( F e. T /\ U e. E ) /\ ( G e. T /\ V e. E ) ) -> ( 1st ` <. G , V >. ) = G ) | 
						
							| 10 | 7 9 | coeq12d |  |-  ( ( ( F e. T /\ U e. E ) /\ ( G e. T /\ V e. E ) ) -> ( ( 1st ` <. F , U >. ) o. ( 1st ` <. G , V >. ) ) = ( F o. G ) ) | 
						
							| 11 |  | op2ndg |  |-  ( ( F e. T /\ U e. E ) -> ( 2nd ` <. F , U >. ) = U ) | 
						
							| 12 |  | op2ndg |  |-  ( ( G e. T /\ V e. E ) -> ( 2nd ` <. G , V >. ) = V ) | 
						
							| 13 | 11 12 | oveqan12d |  |-  ( ( ( F e. T /\ U e. E ) /\ ( G e. T /\ V e. E ) ) -> ( ( 2nd ` <. F , U >. ) P ( 2nd ` <. G , V >. ) ) = ( U P V ) ) | 
						
							| 14 | 10 13 | opeq12d |  |-  ( ( ( F e. T /\ U e. E ) /\ ( G e. T /\ V e. E ) ) -> <. ( ( 1st ` <. F , U >. ) o. ( 1st ` <. G , V >. ) ) , ( ( 2nd ` <. F , U >. ) P ( 2nd ` <. G , V >. ) ) >. = <. ( F o. G ) , ( U P V ) >. ) | 
						
							| 15 | 5 14 | eqtrd |  |-  ( ( ( F e. T /\ U e. E ) /\ ( G e. T /\ V e. E ) ) -> ( <. F , U >. A <. G , V >. ) = <. ( F o. G ) , ( U P V ) >. ) |