| Step | Hyp | Ref | Expression | 
						
							| 1 |  | xporderlem.1 |  |-  T = { <. x , y >. | ( ( x e. ( A X. B ) /\ y e. ( A X. B ) ) /\ ( ( 1st ` x ) R ( 1st ` y ) \/ ( ( 1st ` x ) = ( 1st ` y ) /\ ( 2nd ` x ) S ( 2nd ` y ) ) ) ) } | 
						
							| 2 |  | df-br |  |-  ( <. a , b >. T <. c , d >. <-> <. <. a , b >. , <. c , d >. >. e. T ) | 
						
							| 3 | 1 | eleq2i |  |-  ( <. <. a , b >. , <. c , d >. >. e. T <-> <. <. a , b >. , <. c , d >. >. e. { <. x , y >. | ( ( x e. ( A X. B ) /\ y e. ( A X. B ) ) /\ ( ( 1st ` x ) R ( 1st ` y ) \/ ( ( 1st ` x ) = ( 1st ` y ) /\ ( 2nd ` x ) S ( 2nd ` y ) ) ) ) } ) | 
						
							| 4 | 2 3 | bitri |  |-  ( <. a , b >. T <. c , d >. <-> <. <. a , b >. , <. c , d >. >. e. { <. x , y >. | ( ( x e. ( A X. B ) /\ y e. ( A X. B ) ) /\ ( ( 1st ` x ) R ( 1st ` y ) \/ ( ( 1st ` x ) = ( 1st ` y ) /\ ( 2nd ` x ) S ( 2nd ` y ) ) ) ) } ) | 
						
							| 5 |  | opex |  |-  <. a , b >. e. _V | 
						
							| 6 |  | opex |  |-  <. c , d >. e. _V | 
						
							| 7 |  | eleq1 |  |-  ( x = <. a , b >. -> ( x e. ( A X. B ) <-> <. a , b >. e. ( A X. B ) ) ) | 
						
							| 8 |  | opelxp |  |-  ( <. a , b >. e. ( A X. B ) <-> ( a e. A /\ b e. B ) ) | 
						
							| 9 | 7 8 | bitrdi |  |-  ( x = <. a , b >. -> ( x e. ( A X. B ) <-> ( a e. A /\ b e. B ) ) ) | 
						
							| 10 | 9 | anbi1d |  |-  ( x = <. a , b >. -> ( ( x e. ( A X. B ) /\ y e. ( A X. B ) ) <-> ( ( a e. A /\ b e. B ) /\ y e. ( A X. B ) ) ) ) | 
						
							| 11 |  | vex |  |-  a e. _V | 
						
							| 12 |  | vex |  |-  b e. _V | 
						
							| 13 | 11 12 | op1std |  |-  ( x = <. a , b >. -> ( 1st ` x ) = a ) | 
						
							| 14 | 13 | breq1d |  |-  ( x = <. a , b >. -> ( ( 1st ` x ) R ( 1st ` y ) <-> a R ( 1st ` y ) ) ) | 
						
							| 15 | 13 | eqeq1d |  |-  ( x = <. a , b >. -> ( ( 1st ` x ) = ( 1st ` y ) <-> a = ( 1st ` y ) ) ) | 
						
							| 16 | 11 12 | op2ndd |  |-  ( x = <. a , b >. -> ( 2nd ` x ) = b ) | 
						
							| 17 | 16 | breq1d |  |-  ( x = <. a , b >. -> ( ( 2nd ` x ) S ( 2nd ` y ) <-> b S ( 2nd ` y ) ) ) | 
						
							| 18 | 15 17 | anbi12d |  |-  ( x = <. a , b >. -> ( ( ( 1st ` x ) = ( 1st ` y ) /\ ( 2nd ` x ) S ( 2nd ` y ) ) <-> ( a = ( 1st ` y ) /\ b S ( 2nd ` y ) ) ) ) | 
						
							| 19 | 14 18 | orbi12d |  |-  ( x = <. a , b >. -> ( ( ( 1st ` x ) R ( 1st ` y ) \/ ( ( 1st ` x ) = ( 1st ` y ) /\ ( 2nd ` x ) S ( 2nd ` y ) ) ) <-> ( a R ( 1st ` y ) \/ ( a = ( 1st ` y ) /\ b S ( 2nd ` y ) ) ) ) ) | 
						
							| 20 | 10 19 | anbi12d |  |-  ( x = <. a , b >. -> ( ( ( x e. ( A X. B ) /\ y e. ( A X. B ) ) /\ ( ( 1st ` x ) R ( 1st ` y ) \/ ( ( 1st ` x ) = ( 1st ` y ) /\ ( 2nd ` x ) S ( 2nd ` y ) ) ) ) <-> ( ( ( a e. A /\ b e. B ) /\ y e. ( A X. B ) ) /\ ( a R ( 1st ` y ) \/ ( a = ( 1st ` y ) /\ b S ( 2nd ` y ) ) ) ) ) ) | 
						
							| 21 |  | eleq1 |  |-  ( y = <. c , d >. -> ( y e. ( A X. B ) <-> <. c , d >. e. ( A X. B ) ) ) | 
						
							| 22 |  | opelxp |  |-  ( <. c , d >. e. ( A X. B ) <-> ( c e. A /\ d e. B ) ) | 
						
							| 23 | 21 22 | bitrdi |  |-  ( y = <. c , d >. -> ( y e. ( A X. B ) <-> ( c e. A /\ d e. B ) ) ) | 
						
							| 24 | 23 | anbi2d |  |-  ( y = <. c , d >. -> ( ( ( a e. A /\ b e. B ) /\ y e. ( A X. B ) ) <-> ( ( a e. A /\ b e. B ) /\ ( c e. A /\ d e. B ) ) ) ) | 
						
							| 25 |  | vex |  |-  c e. _V | 
						
							| 26 |  | vex |  |-  d e. _V | 
						
							| 27 | 25 26 | op1std |  |-  ( y = <. c , d >. -> ( 1st ` y ) = c ) | 
						
							| 28 | 27 | breq2d |  |-  ( y = <. c , d >. -> ( a R ( 1st ` y ) <-> a R c ) ) | 
						
							| 29 | 27 | eqeq2d |  |-  ( y = <. c , d >. -> ( a = ( 1st ` y ) <-> a = c ) ) | 
						
							| 30 | 25 26 | op2ndd |  |-  ( y = <. c , d >. -> ( 2nd ` y ) = d ) | 
						
							| 31 | 30 | breq2d |  |-  ( y = <. c , d >. -> ( b S ( 2nd ` y ) <-> b S d ) ) | 
						
							| 32 | 29 31 | anbi12d |  |-  ( y = <. c , d >. -> ( ( a = ( 1st ` y ) /\ b S ( 2nd ` y ) ) <-> ( a = c /\ b S d ) ) ) | 
						
							| 33 | 28 32 | orbi12d |  |-  ( y = <. c , d >. -> ( ( a R ( 1st ` y ) \/ ( a = ( 1st ` y ) /\ b S ( 2nd ` y ) ) ) <-> ( a R c \/ ( a = c /\ b S d ) ) ) ) | 
						
							| 34 | 24 33 | anbi12d |  |-  ( y = <. c , d >. -> ( ( ( ( a e. A /\ b e. B ) /\ y e. ( A X. B ) ) /\ ( a R ( 1st ` y ) \/ ( a = ( 1st ` y ) /\ b S ( 2nd ` y ) ) ) ) <-> ( ( ( a e. A /\ b e. B ) /\ ( c e. A /\ d e. B ) ) /\ ( a R c \/ ( a = c /\ b S d ) ) ) ) ) | 
						
							| 35 | 5 6 20 34 | opelopab |  |-  ( <. <. a , b >. , <. c , d >. >. e. { <. x , y >. | ( ( x e. ( A X. B ) /\ y e. ( A X. B ) ) /\ ( ( 1st ` x ) R ( 1st ` y ) \/ ( ( 1st ` x ) = ( 1st ` y ) /\ ( 2nd ` x ) S ( 2nd ` y ) ) ) ) } <-> ( ( ( a e. A /\ b e. B ) /\ ( c e. A /\ d e. B ) ) /\ ( a R c \/ ( a = c /\ b S d ) ) ) ) | 
						
							| 36 |  | an4 |  |-  ( ( ( a e. A /\ b e. B ) /\ ( c e. A /\ d e. B ) ) <-> ( ( a e. A /\ c e. A ) /\ ( b e. B /\ d e. B ) ) ) | 
						
							| 37 | 36 | anbi1i |  |-  ( ( ( ( a e. A /\ b e. B ) /\ ( c e. A /\ d e. B ) ) /\ ( a R c \/ ( a = c /\ b S d ) ) ) <-> ( ( ( a e. A /\ c e. A ) /\ ( b e. B /\ d e. B ) ) /\ ( a R c \/ ( a = c /\ b S d ) ) ) ) | 
						
							| 38 | 4 35 37 | 3bitri |  |-  ( <. a , b >. T <. c , d >. <-> ( ( ( a e. A /\ c e. A ) /\ ( b e. B /\ d e. B ) ) /\ ( a R c \/ ( a = c /\ b S d ) ) ) ) |