| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 2zrng.e |  |-  E = { z e. ZZ | E. x e. ZZ z = ( 2 x. x ) } | 
						
							| 2 |  | 2zrngbas.r |  |-  R = ( CCfld |`s E ) | 
						
							| 3 |  | 2zrngmmgm.1 |  |-  M = ( mulGrp ` R ) | 
						
							| 4 |  | eqeq1 |  |-  ( z = a -> ( z = ( 2 x. x ) <-> a = ( 2 x. x ) ) ) | 
						
							| 5 | 4 | rexbidv |  |-  ( z = a -> ( E. x e. ZZ z = ( 2 x. x ) <-> E. x e. ZZ a = ( 2 x. x ) ) ) | 
						
							| 6 | 5 1 | elrab2 |  |-  ( a e. E <-> ( a e. ZZ /\ E. x e. ZZ a = ( 2 x. x ) ) ) | 
						
							| 7 |  | eqeq1 |  |-  ( z = b -> ( z = ( 2 x. x ) <-> b = ( 2 x. x ) ) ) | 
						
							| 8 | 7 | rexbidv |  |-  ( z = b -> ( E. x e. ZZ z = ( 2 x. x ) <-> E. x e. ZZ b = ( 2 x. x ) ) ) | 
						
							| 9 | 8 1 | elrab2 |  |-  ( b e. E <-> ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) | 
						
							| 10 |  | zmulcl |  |-  ( ( a e. ZZ /\ b e. ZZ ) -> ( a x. b ) e. ZZ ) | 
						
							| 11 | 10 | ad2ant2r |  |-  ( ( ( a e. ZZ /\ E. x e. ZZ a = ( 2 x. x ) ) /\ ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) -> ( a x. b ) e. ZZ ) | 
						
							| 12 |  | nfv |  |-  F/ x a e. ZZ | 
						
							| 13 |  | nfv |  |-  F/ x b e. ZZ | 
						
							| 14 |  | nfre1 |  |-  F/ x E. x e. ZZ b = ( 2 x. x ) | 
						
							| 15 | 13 14 | nfan |  |-  F/ x ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) | 
						
							| 16 |  | nfv |  |-  F/ x E. y e. ZZ ( a x. b ) = ( 2 x. y ) | 
						
							| 17 | 15 16 | nfim |  |-  F/ x ( ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) -> E. y e. ZZ ( a x. b ) = ( 2 x. y ) ) | 
						
							| 18 | 12 17 | nfim |  |-  F/ x ( a e. ZZ -> ( ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) -> E. y e. ZZ ( a x. b ) = ( 2 x. y ) ) ) | 
						
							| 19 |  | simpll |  |-  ( ( ( x e. ZZ /\ a = ( 2 x. x ) ) /\ a e. ZZ ) -> x e. ZZ ) | 
						
							| 20 |  | simpl |  |-  ( ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) -> b e. ZZ ) | 
						
							| 21 |  | zmulcl |  |-  ( ( x e. ZZ /\ b e. ZZ ) -> ( x x. b ) e. ZZ ) | 
						
							| 22 | 19 20 21 | syl2an |  |-  ( ( ( ( x e. ZZ /\ a = ( 2 x. x ) ) /\ a e. ZZ ) /\ ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) -> ( x x. b ) e. ZZ ) | 
						
							| 23 |  | oveq2 |  |-  ( y = ( x x. b ) -> ( 2 x. y ) = ( 2 x. ( x x. b ) ) ) | 
						
							| 24 | 23 | eqeq2d |  |-  ( y = ( x x. b ) -> ( ( a x. b ) = ( 2 x. y ) <-> ( a x. b ) = ( 2 x. ( x x. b ) ) ) ) | 
						
							| 25 | 24 | adantl |  |-  ( ( ( ( ( x e. ZZ /\ a = ( 2 x. x ) ) /\ a e. ZZ ) /\ ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) /\ y = ( x x. b ) ) -> ( ( a x. b ) = ( 2 x. y ) <-> ( a x. b ) = ( 2 x. ( x x. b ) ) ) ) | 
						
							| 26 |  | oveq1 |  |-  ( a = ( 2 x. x ) -> ( a x. b ) = ( ( 2 x. x ) x. b ) ) | 
						
							| 27 | 26 | ad3antlr |  |-  ( ( ( ( x e. ZZ /\ a = ( 2 x. x ) ) /\ a e. ZZ ) /\ ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) -> ( a x. b ) = ( ( 2 x. x ) x. b ) ) | 
						
							| 28 |  | 2cnd |  |-  ( ( ( ( x e. ZZ /\ a = ( 2 x. x ) ) /\ a e. ZZ ) /\ ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) -> 2 e. CC ) | 
						
							| 29 |  | zcn |  |-  ( x e. ZZ -> x e. CC ) | 
						
							| 30 | 29 | ad3antrrr |  |-  ( ( ( ( x e. ZZ /\ a = ( 2 x. x ) ) /\ a e. ZZ ) /\ ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) -> x e. CC ) | 
						
							| 31 |  | zcn |  |-  ( b e. ZZ -> b e. CC ) | 
						
							| 32 | 31 | adantr |  |-  ( ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) -> b e. CC ) | 
						
							| 33 | 32 | adantl |  |-  ( ( ( ( x e. ZZ /\ a = ( 2 x. x ) ) /\ a e. ZZ ) /\ ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) -> b e. CC ) | 
						
							| 34 | 28 30 33 | mulassd |  |-  ( ( ( ( x e. ZZ /\ a = ( 2 x. x ) ) /\ a e. ZZ ) /\ ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) -> ( ( 2 x. x ) x. b ) = ( 2 x. ( x x. b ) ) ) | 
						
							| 35 | 27 34 | eqtrd |  |-  ( ( ( ( x e. ZZ /\ a = ( 2 x. x ) ) /\ a e. ZZ ) /\ ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) -> ( a x. b ) = ( 2 x. ( x x. b ) ) ) | 
						
							| 36 | 22 25 35 | rspcedvd |  |-  ( ( ( ( x e. ZZ /\ a = ( 2 x. x ) ) /\ a e. ZZ ) /\ ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) -> E. y e. ZZ ( a x. b ) = ( 2 x. y ) ) | 
						
							| 37 | 36 | exp41 |  |-  ( x e. ZZ -> ( a = ( 2 x. x ) -> ( a e. ZZ -> ( ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) -> E. y e. ZZ ( a x. b ) = ( 2 x. y ) ) ) ) ) | 
						
							| 38 | 18 37 | rexlimi |  |-  ( E. x e. ZZ a = ( 2 x. x ) -> ( a e. ZZ -> ( ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) -> E. y e. ZZ ( a x. b ) = ( 2 x. y ) ) ) ) | 
						
							| 39 | 38 | impcom |  |-  ( ( a e. ZZ /\ E. x e. ZZ a = ( 2 x. x ) ) -> ( ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) -> E. y e. ZZ ( a x. b ) = ( 2 x. y ) ) ) | 
						
							| 40 | 39 | imp |  |-  ( ( ( a e. ZZ /\ E. x e. ZZ a = ( 2 x. x ) ) /\ ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) -> E. y e. ZZ ( a x. b ) = ( 2 x. y ) ) | 
						
							| 41 |  | eqeq1 |  |-  ( z = ( a x. b ) -> ( z = ( 2 x. x ) <-> ( a x. b ) = ( 2 x. x ) ) ) | 
						
							| 42 | 41 | rexbidv |  |-  ( z = ( a x. b ) -> ( E. x e. ZZ z = ( 2 x. x ) <-> E. x e. ZZ ( a x. b ) = ( 2 x. x ) ) ) | 
						
							| 43 | 42 1 | elrab2 |  |-  ( ( a x. b ) e. E <-> ( ( a x. b ) e. ZZ /\ E. x e. ZZ ( a x. b ) = ( 2 x. x ) ) ) | 
						
							| 44 |  | oveq2 |  |-  ( x = y -> ( 2 x. x ) = ( 2 x. y ) ) | 
						
							| 45 | 44 | eqeq2d |  |-  ( x = y -> ( ( a x. b ) = ( 2 x. x ) <-> ( a x. b ) = ( 2 x. y ) ) ) | 
						
							| 46 | 45 | cbvrexvw |  |-  ( E. x e. ZZ ( a x. b ) = ( 2 x. x ) <-> E. y e. ZZ ( a x. b ) = ( 2 x. y ) ) | 
						
							| 47 | 46 | anbi2i |  |-  ( ( ( a x. b ) e. ZZ /\ E. x e. ZZ ( a x. b ) = ( 2 x. x ) ) <-> ( ( a x. b ) e. ZZ /\ E. y e. ZZ ( a x. b ) = ( 2 x. y ) ) ) | 
						
							| 48 | 43 47 | bitri |  |-  ( ( a x. b ) e. E <-> ( ( a x. b ) e. ZZ /\ E. y e. ZZ ( a x. b ) = ( 2 x. y ) ) ) | 
						
							| 49 | 11 40 48 | sylanbrc |  |-  ( ( ( a e. ZZ /\ E. x e. ZZ a = ( 2 x. x ) ) /\ ( b e. ZZ /\ E. x e. ZZ b = ( 2 x. x ) ) ) -> ( a x. b ) e. E ) | 
						
							| 50 | 6 9 49 | syl2anb |  |-  ( ( a e. E /\ b e. E ) -> ( a x. b ) e. E ) | 
						
							| 51 | 50 | rgen2 |  |-  A. a e. E A. b e. E ( a x. b ) e. E | 
						
							| 52 | 1 | 0even |  |-  0 e. E | 
						
							| 53 | 1 2 | 2zrngbas |  |-  E = ( Base ` R ) | 
						
							| 54 | 3 53 | mgpbas |  |-  E = ( Base ` M ) | 
						
							| 55 | 1 2 | 2zrngmul |  |-  x. = ( .r ` R ) | 
						
							| 56 | 3 55 | mgpplusg |  |-  x. = ( +g ` M ) | 
						
							| 57 | 54 56 | ismgmn0 |  |-  ( 0 e. E -> ( M e. Mgm <-> A. a e. E A. b e. E ( a x. b ) e. E ) ) | 
						
							| 58 | 52 57 | ax-mp |  |-  ( M e. Mgm <-> A. a e. E A. b e. E ( a x. b ) e. E ) | 
						
							| 59 | 51 58 | mpbir |  |-  M e. Mgm |