| Step | Hyp | Ref | Expression | 
						
							| 1 |  | nfv |  |-  F/ a ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) | 
						
							| 2 |  | nfv |  |-  F/ a <. A , B >. = <. x , y >. | 
						
							| 3 |  | nfcv |  |-  F/_ a y | 
						
							| 4 |  | nfsbc1v |  |-  F/ a [. x / a ]. ( a R b /\ ph ) | 
						
							| 5 | 3 4 | nfsbcw |  |-  F/ a [. y / b ]. [. x / a ]. ( a R b /\ ph ) | 
						
							| 6 | 2 5 | nfan |  |-  F/ a ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) | 
						
							| 7 | 6 | nfex |  |-  F/ a E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) | 
						
							| 8 | 7 | nfex |  |-  F/ a E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) | 
						
							| 9 |  | nfv |  |-  F/ b ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) | 
						
							| 10 |  | nfv |  |-  F/ b <. A , B >. = <. x , y >. | 
						
							| 11 |  | nfsbc1v |  |-  F/ b [. y / b ]. [. x / a ]. ( a R b /\ ph ) | 
						
							| 12 | 10 11 | nfan |  |-  F/ b ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) | 
						
							| 13 | 12 | nfex |  |-  F/ b E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) | 
						
							| 14 | 13 | nfex |  |-  F/ b E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) | 
						
							| 15 |  | vex |  |-  a e. _V | 
						
							| 16 |  | vex |  |-  b e. _V | 
						
							| 17 |  | preq12bg |  |-  ( ( ( A e. X /\ B e. X ) /\ ( a e. _V /\ b e. _V ) ) -> ( { A , B } = { a , b } <-> ( ( A = a /\ B = b ) \/ ( A = b /\ B = a ) ) ) ) | 
						
							| 18 | 15 16 17 | mpanr12 |  |-  ( ( A e. X /\ B e. X ) -> ( { A , B } = { a , b } <-> ( ( A = a /\ B = b ) \/ ( A = b /\ B = a ) ) ) ) | 
						
							| 19 | 18 | 3adant3 |  |-  ( ( A e. X /\ B e. X /\ A R B ) -> ( { A , B } = { a , b } <-> ( ( A = a /\ B = b ) \/ ( A = b /\ B = a ) ) ) ) | 
						
							| 20 | 19 | adantl |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> ( { A , B } = { a , b } <-> ( ( A = a /\ B = b ) \/ ( A = b /\ B = a ) ) ) ) | 
						
							| 21 |  | or2expropbilem1 |  |-  ( ( A e. X /\ B e. X ) -> ( ( A = a /\ B = b ) -> ( ( a R b /\ ph ) -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) ) | 
						
							| 22 | 21 | 3adant3 |  |-  ( ( A e. X /\ B e. X /\ A R B ) -> ( ( A = a /\ B = b ) -> ( ( a R b /\ ph ) -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) ) | 
						
							| 23 | 22 | adantl |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> ( ( A = a /\ B = b ) -> ( ( a R b /\ ph ) -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) ) | 
						
							| 24 |  | breq12 |  |-  ( ( B = a /\ A = b ) -> ( B R A <-> a R b ) ) | 
						
							| 25 | 24 | ancoms |  |-  ( ( A = b /\ B = a ) -> ( B R A <-> a R b ) ) | 
						
							| 26 | 25 | adantl |  |-  ( ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) /\ ( A = b /\ B = a ) ) -> ( B R A <-> a R b ) ) | 
						
							| 27 |  | soasym |  |-  ( ( R Or X /\ ( A e. X /\ B e. X ) ) -> ( A R B -> -. B R A ) ) | 
						
							| 28 | 27 | ex |  |-  ( R Or X -> ( ( A e. X /\ B e. X ) -> ( A R B -> -. B R A ) ) ) | 
						
							| 29 | 28 | adantl |  |-  ( ( X e. V /\ R Or X ) -> ( ( A e. X /\ B e. X ) -> ( A R B -> -. B R A ) ) ) | 
						
							| 30 | 29 | expd |  |-  ( ( X e. V /\ R Or X ) -> ( A e. X -> ( B e. X -> ( A R B -> -. B R A ) ) ) ) | 
						
							| 31 | 30 | 3imp2 |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> -. B R A ) | 
						
							| 32 | 31 | pm2.21d |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> ( B R A -> ( ph -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) ) | 
						
							| 33 | 32 | adantr |  |-  ( ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) /\ ( A = b /\ B = a ) ) -> ( B R A -> ( ph -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) ) | 
						
							| 34 | 26 33 | sylbird |  |-  ( ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) /\ ( A = b /\ B = a ) ) -> ( a R b -> ( ph -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) ) | 
						
							| 35 | 34 | impd |  |-  ( ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) /\ ( A = b /\ B = a ) ) -> ( ( a R b /\ ph ) -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) | 
						
							| 36 | 35 | ex |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> ( ( A = b /\ B = a ) -> ( ( a R b /\ ph ) -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) ) | 
						
							| 37 | 23 36 | jaod |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> ( ( ( A = a /\ B = b ) \/ ( A = b /\ B = a ) ) -> ( ( a R b /\ ph ) -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) ) | 
						
							| 38 | 20 37 | sylbid |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> ( { A , B } = { a , b } -> ( ( a R b /\ ph ) -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) ) | 
						
							| 39 | 38 | impd |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> ( ( { A , B } = { a , b } /\ ( a R b /\ ph ) ) -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) | 
						
							| 40 | 9 14 39 | exlimd |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> ( E. b ( { A , B } = { a , b } /\ ( a R b /\ ph ) ) -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) | 
						
							| 41 | 1 8 40 | exlimd |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> ( E. a E. b ( { A , B } = { a , b } /\ ( a R b /\ ph ) ) -> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) ) | 
						
							| 42 |  | or2expropbilem2 |  |-  ( E. a E. b ( <. A , B >. = <. a , b >. /\ ( a R b /\ ph ) ) <-> E. x E. y ( <. A , B >. = <. x , y >. /\ [. y / b ]. [. x / a ]. ( a R b /\ ph ) ) ) | 
						
							| 43 | 41 42 | imbitrrdi |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> ( E. a E. b ( { A , B } = { a , b } /\ ( a R b /\ ph ) ) -> E. a E. b ( <. A , B >. = <. a , b >. /\ ( a R b /\ ph ) ) ) ) | 
						
							| 44 |  | oppr |  |-  ( ( A e. X /\ B e. X ) -> ( <. A , B >. = <. a , b >. -> { A , B } = { a , b } ) ) | 
						
							| 45 | 44 | anim1d |  |-  ( ( A e. X /\ B e. X ) -> ( ( <. A , B >. = <. a , b >. /\ ( a R b /\ ph ) ) -> ( { A , B } = { a , b } /\ ( a R b /\ ph ) ) ) ) | 
						
							| 46 | 45 | 2eximdv |  |-  ( ( A e. X /\ B e. X ) -> ( E. a E. b ( <. A , B >. = <. a , b >. /\ ( a R b /\ ph ) ) -> E. a E. b ( { A , B } = { a , b } /\ ( a R b /\ ph ) ) ) ) | 
						
							| 47 | 46 | 3adant3 |  |-  ( ( A e. X /\ B e. X /\ A R B ) -> ( E. a E. b ( <. A , B >. = <. a , b >. /\ ( a R b /\ ph ) ) -> E. a E. b ( { A , B } = { a , b } /\ ( a R b /\ ph ) ) ) ) | 
						
							| 48 | 47 | adantl |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> ( E. a E. b ( <. A , B >. = <. a , b >. /\ ( a R b /\ ph ) ) -> E. a E. b ( { A , B } = { a , b } /\ ( a R b /\ ph ) ) ) ) | 
						
							| 49 | 43 48 | impbid |  |-  ( ( ( X e. V /\ R Or X ) /\ ( A e. X /\ B e. X /\ A R B ) ) -> ( E. a E. b ( { A , B } = { a , b } /\ ( a R b /\ ph ) ) <-> E. a E. b ( <. A , B >. = <. a , b >. /\ ( a R b /\ ph ) ) ) ) |