| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							opex | 
							 |-  <. <. x , y >. , z >. e. _V  | 
						
						
							| 2 | 
							
								
							 | 
							opex | 
							 |-  <. x , y >. e. _V  | 
						
						
							| 3 | 
							
								
							 | 
							vex | 
							 |-  z e. _V  | 
						
						
							| 4 | 
							
								2 3
							 | 
							eqvinop | 
							 |-  ( w = <. <. x , y >. , z >. <-> E. a E. t ( w = <. a , t >. /\ <. a , t >. = <. <. x , y >. , z >. ) )  | 
						
						
							| 5 | 
							
								4
							 | 
							biimpi | 
							 |-  ( w = <. <. x , y >. , z >. -> E. a E. t ( w = <. a , t >. /\ <. a , t >. = <. <. x , y >. , z >. ) )  | 
						
						
							| 6 | 
							
								
							 | 
							eqeq1 | 
							 |-  ( w = <. a , t >. -> ( w = <. <. x , y >. , z >. <-> <. a , t >. = <. <. x , y >. , z >. ) )  | 
						
						
							| 7 | 
							
								
							 | 
							vex | 
							 |-  a e. _V  | 
						
						
							| 8 | 
							
								
							 | 
							vex | 
							 |-  t e. _V  | 
						
						
							| 9 | 
							
								7 8
							 | 
							opth1 | 
							 |-  ( <. a , t >. = <. <. x , y >. , z >. -> a = <. x , y >. )  | 
						
						
							| 10 | 
							
								6 9
							 | 
							biimtrdi | 
							 |-  ( w = <. a , t >. -> ( w = <. <. x , y >. , z >. -> a = <. x , y >. ) )  | 
						
						
							| 11 | 
							
								
							 | 
							vex | 
							 |-  x e. _V  | 
						
						
							| 12 | 
							
								
							 | 
							vex | 
							 |-  y e. _V  | 
						
						
							| 13 | 
							
								11 12
							 | 
							eqvinop | 
							 |-  ( a = <. x , y >. <-> E. r E. s ( a = <. r , s >. /\ <. r , s >. = <. x , y >. ) )  | 
						
						
							| 14 | 
							
								
							 | 
							opeq1 | 
							 |-  ( a = <. r , s >. -> <. a , t >. = <. <. r , s >. , t >. )  | 
						
						
							| 15 | 
							
								14
							 | 
							eqeq2d | 
							 |-  ( a = <. r , s >. -> ( w = <. a , t >. <-> w = <. <. r , s >. , t >. ) )  | 
						
						
							| 16 | 
							
								11 12 3
							 | 
							otth2 | 
							 |-  ( <. <. x , y >. , z >. = <. <. r , s >. , t >. <-> ( x = r /\ y = s /\ z = t ) )  | 
						
						
							| 17 | 
							
								
							 | 
							euequ | 
							 |-  E! x x = r  | 
						
						
							| 18 | 
							
								
							 | 
							eupick | 
							 |-  ( ( E! x x = r /\ E. x ( x = r /\ E. y ( y = s /\ E. z ( z = t /\ ph ) ) ) ) -> ( x = r -> E. y ( y = s /\ E. z ( z = t /\ ph ) ) ) )  | 
						
						
							| 19 | 
							
								17 18
							 | 
							mpan | 
							 |-  ( E. x ( x = r /\ E. y ( y = s /\ E. z ( z = t /\ ph ) ) ) -> ( x = r -> E. y ( y = s /\ E. z ( z = t /\ ph ) ) ) )  | 
						
						
							| 20 | 
							
								
							 | 
							euequ | 
							 |-  E! y y = s  | 
						
						
							| 21 | 
							
								
							 | 
							eupick | 
							 |-  ( ( E! y y = s /\ E. y ( y = s /\ E. z ( z = t /\ ph ) ) ) -> ( y = s -> E. z ( z = t /\ ph ) ) )  | 
						
						
							| 22 | 
							
								20 21
							 | 
							mpan | 
							 |-  ( E. y ( y = s /\ E. z ( z = t /\ ph ) ) -> ( y = s -> E. z ( z = t /\ ph ) ) )  | 
						
						
							| 23 | 
							
								
							 | 
							euequ | 
							 |-  E! z z = t  | 
						
						
							| 24 | 
							
								
							 | 
							eupick | 
							 |-  ( ( E! z z = t /\ E. z ( z = t /\ ph ) ) -> ( z = t -> ph ) )  | 
						
						
							| 25 | 
							
								23 24
							 | 
							mpan | 
							 |-  ( E. z ( z = t /\ ph ) -> ( z = t -> ph ) )  | 
						
						
							| 26 | 
							
								22 25
							 | 
							syl6 | 
							 |-  ( E. y ( y = s /\ E. z ( z = t /\ ph ) ) -> ( y = s -> ( z = t -> ph ) ) )  | 
						
						
							| 27 | 
							
								19 26
							 | 
							syl6 | 
							 |-  ( E. x ( x = r /\ E. y ( y = s /\ E. z ( z = t /\ ph ) ) ) -> ( x = r -> ( y = s -> ( z = t -> ph ) ) ) )  | 
						
						
							| 28 | 
							
								27
							 | 
							3impd | 
							 |-  ( E. x ( x = r /\ E. y ( y = s /\ E. z ( z = t /\ ph ) ) ) -> ( ( x = r /\ y = s /\ z = t ) -> ph ) )  | 
						
						
							| 29 | 
							
								16 28
							 | 
							biimtrid | 
							 |-  ( E. x ( x = r /\ E. y ( y = s /\ E. z ( z = t /\ ph ) ) ) -> ( <. <. x , y >. , z >. = <. <. r , s >. , t >. -> ph ) )  | 
						
						
							| 30 | 
							
								
							 | 
							df-3an | 
							 |-  ( ( x = r /\ y = s /\ z = t ) <-> ( ( x = r /\ y = s ) /\ z = t ) )  | 
						
						
							| 31 | 
							
								16 30
							 | 
							bitri | 
							 |-  ( <. <. x , y >. , z >. = <. <. r , s >. , t >. <-> ( ( x = r /\ y = s ) /\ z = t ) )  | 
						
						
							| 32 | 
							
								31
							 | 
							anbi1i | 
							 |-  ( ( <. <. x , y >. , z >. = <. <. r , s >. , t >. /\ ph ) <-> ( ( ( x = r /\ y = s ) /\ z = t ) /\ ph ) )  | 
						
						
							| 33 | 
							
								
							 | 
							anass | 
							 |-  ( ( ( ( x = r /\ y = s ) /\ z = t ) /\ ph ) <-> ( ( x = r /\ y = s ) /\ ( z = t /\ ph ) ) )  | 
						
						
							| 34 | 
							
								
							 | 
							anass | 
							 |-  ( ( ( x = r /\ y = s ) /\ ( z = t /\ ph ) ) <-> ( x = r /\ ( y = s /\ ( z = t /\ ph ) ) ) )  | 
						
						
							| 35 | 
							
								32 33 34
							 | 
							3bitri | 
							 |-  ( ( <. <. x , y >. , z >. = <. <. r , s >. , t >. /\ ph ) <-> ( x = r /\ ( y = s /\ ( z = t /\ ph ) ) ) )  | 
						
						
							| 36 | 
							
								35
							 | 
							3exbii | 
							 |-  ( E. x E. y E. z ( <. <. x , y >. , z >. = <. <. r , s >. , t >. /\ ph ) <-> E. x E. y E. z ( x = r /\ ( y = s /\ ( z = t /\ ph ) ) ) )  | 
						
						
							| 37 | 
							
								
							 | 
							nfcvf2 | 
							 |-  ( -. A. x x = z -> F/_ z x )  | 
						
						
							| 38 | 
							
								
							 | 
							nfcvd | 
							 |-  ( -. A. x x = z -> F/_ z r )  | 
						
						
							| 39 | 
							
								37 38
							 | 
							nfeqd | 
							 |-  ( -. A. x x = z -> F/ z x = r )  | 
						
						
							| 40 | 
							
								39
							 | 
							exdistrf | 
							 |-  ( E. x E. z ( x = r /\ ( y = s /\ ( z = t /\ ph ) ) ) -> E. x ( x = r /\ E. z ( y = s /\ ( z = t /\ ph ) ) ) )  | 
						
						
							| 41 | 
							
								40
							 | 
							eximi | 
							 |-  ( E. y E. x E. z ( x = r /\ ( y = s /\ ( z = t /\ ph ) ) ) -> E. y E. x ( x = r /\ E. z ( y = s /\ ( z = t /\ ph ) ) ) )  | 
						
						
							| 42 | 
							
								
							 | 
							excom | 
							 |-  ( E. x E. y E. z ( x = r /\ ( y = s /\ ( z = t /\ ph ) ) ) <-> E. y E. x E. z ( x = r /\ ( y = s /\ ( z = t /\ ph ) ) ) )  | 
						
						
							| 43 | 
							
								
							 | 
							excom | 
							 |-  ( E. x E. y ( x = r /\ E. z ( y = s /\ ( z = t /\ ph ) ) ) <-> E. y E. x ( x = r /\ E. z ( y = s /\ ( z = t /\ ph ) ) ) )  | 
						
						
							| 44 | 
							
								41 42 43
							 | 
							3imtr4i | 
							 |-  ( E. x E. y E. z ( x = r /\ ( y = s /\ ( z = t /\ ph ) ) ) -> E. x E. y ( x = r /\ E. z ( y = s /\ ( z = t /\ ph ) ) ) )  | 
						
						
							| 45 | 
							
								
							 | 
							nfcvf2 | 
							 |-  ( -. A. x x = y -> F/_ y x )  | 
						
						
							| 46 | 
							
								
							 | 
							nfcvd | 
							 |-  ( -. A. x x = y -> F/_ y r )  | 
						
						
							| 47 | 
							
								45 46
							 | 
							nfeqd | 
							 |-  ( -. A. x x = y -> F/ y x = r )  | 
						
						
							| 48 | 
							
								47
							 | 
							exdistrf | 
							 |-  ( E. x E. y ( x = r /\ E. z ( y = s /\ ( z = t /\ ph ) ) ) -> E. x ( x = r /\ E. y E. z ( y = s /\ ( z = t /\ ph ) ) ) )  | 
						
						
							| 49 | 
							
								
							 | 
							nfcvf2 | 
							 |-  ( -. A. y y = z -> F/_ z y )  | 
						
						
							| 50 | 
							
								
							 | 
							nfcvd | 
							 |-  ( -. A. y y = z -> F/_ z s )  | 
						
						
							| 51 | 
							
								49 50
							 | 
							nfeqd | 
							 |-  ( -. A. y y = z -> F/ z y = s )  | 
						
						
							| 52 | 
							
								51
							 | 
							exdistrf | 
							 |-  ( E. y E. z ( y = s /\ ( z = t /\ ph ) ) -> E. y ( y = s /\ E. z ( z = t /\ ph ) ) )  | 
						
						
							| 53 | 
							
								52
							 | 
							anim2i | 
							 |-  ( ( x = r /\ E. y E. z ( y = s /\ ( z = t /\ ph ) ) ) -> ( x = r /\ E. y ( y = s /\ E. z ( z = t /\ ph ) ) ) )  | 
						
						
							| 54 | 
							
								53
							 | 
							eximi | 
							 |-  ( E. x ( x = r /\ E. y E. z ( y = s /\ ( z = t /\ ph ) ) ) -> E. x ( x = r /\ E. y ( y = s /\ E. z ( z = t /\ ph ) ) ) )  | 
						
						
							| 55 | 
							
								44 48 54
							 | 
							3syl | 
							 |-  ( E. x E. y E. z ( x = r /\ ( y = s /\ ( z = t /\ ph ) ) ) -> E. x ( x = r /\ E. y ( y = s /\ E. z ( z = t /\ ph ) ) ) )  | 
						
						
							| 56 | 
							
								36 55
							 | 
							sylbi | 
							 |-  ( E. x E. y E. z ( <. <. x , y >. , z >. = <. <. r , s >. , t >. /\ ph ) -> E. x ( x = r /\ E. y ( y = s /\ E. z ( z = t /\ ph ) ) ) )  | 
						
						
							| 57 | 
							
								29 56
							 | 
							syl11 | 
							 |-  ( <. <. x , y >. , z >. = <. <. r , s >. , t >. -> ( E. x E. y E. z ( <. <. x , y >. , z >. = <. <. r , s >. , t >. /\ ph ) -> ph ) )  | 
						
						
							| 58 | 
							
								
							 | 
							eqeq1 | 
							 |-  ( w = <. <. r , s >. , t >. -> ( w = <. <. x , y >. , z >. <-> <. <. r , s >. , t >. = <. <. x , y >. , z >. ) )  | 
						
						
							| 59 | 
							
								
							 | 
							eqcom | 
							 |-  ( <. <. r , s >. , t >. = <. <. x , y >. , z >. <-> <. <. x , y >. , z >. = <. <. r , s >. , t >. )  | 
						
						
							| 60 | 
							
								58 59
							 | 
							bitrdi | 
							 |-  ( w = <. <. r , s >. , t >. -> ( w = <. <. x , y >. , z >. <-> <. <. x , y >. , z >. = <. <. r , s >. , t >. ) )  | 
						
						
							| 61 | 
							
								60
							 | 
							anbi1d | 
							 |-  ( w = <. <. r , s >. , t >. -> ( ( w = <. <. x , y >. , z >. /\ ph ) <-> ( <. <. x , y >. , z >. = <. <. r , s >. , t >. /\ ph ) ) )  | 
						
						
							| 62 | 
							
								61
							 | 
							3exbidv | 
							 |-  ( w = <. <. r , s >. , t >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) <-> E. x E. y E. z ( <. <. x , y >. , z >. = <. <. r , s >. , t >. /\ ph ) ) )  | 
						
						
							| 63 | 
							
								62
							 | 
							imbi1d | 
							 |-  ( w = <. <. r , s >. , t >. -> ( ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> ph ) <-> ( E. x E. y E. z ( <. <. x , y >. , z >. = <. <. r , s >. , t >. /\ ph ) -> ph ) ) )  | 
						
						
							| 64 | 
							
								60 63
							 | 
							imbi12d | 
							 |-  ( w = <. <. r , s >. , t >. -> ( ( w = <. <. x , y >. , z >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> ph ) ) <-> ( <. <. x , y >. , z >. = <. <. r , s >. , t >. -> ( E. x E. y E. z ( <. <. x , y >. , z >. = <. <. r , s >. , t >. /\ ph ) -> ph ) ) ) )  | 
						
						
							| 65 | 
							
								57 64
							 | 
							mpbiri | 
							 |-  ( w = <. <. r , s >. , t >. -> ( w = <. <. x , y >. , z >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> ph ) ) )  | 
						
						
							| 66 | 
							
								15 65
							 | 
							biimtrdi | 
							 |-  ( a = <. r , s >. -> ( w = <. a , t >. -> ( w = <. <. x , y >. , z >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> ph ) ) ) )  | 
						
						
							| 67 | 
							
								66
							 | 
							adantr | 
							 |-  ( ( a = <. r , s >. /\ <. r , s >. = <. x , y >. ) -> ( w = <. a , t >. -> ( w = <. <. x , y >. , z >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> ph ) ) ) )  | 
						
						
							| 68 | 
							
								67
							 | 
							exlimivv | 
							 |-  ( E. r E. s ( a = <. r , s >. /\ <. r , s >. = <. x , y >. ) -> ( w = <. a , t >. -> ( w = <. <. x , y >. , z >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> ph ) ) ) )  | 
						
						
							| 69 | 
							
								13 68
							 | 
							sylbi | 
							 |-  ( a = <. x , y >. -> ( w = <. a , t >. -> ( w = <. <. x , y >. , z >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> ph ) ) ) )  | 
						
						
							| 70 | 
							
								69
							 | 
							com3l | 
							 |-  ( w = <. a , t >. -> ( w = <. <. x , y >. , z >. -> ( a = <. x , y >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> ph ) ) ) )  | 
						
						
							| 71 | 
							
								10 70
							 | 
							mpdd | 
							 |-  ( w = <. a , t >. -> ( w = <. <. x , y >. , z >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> ph ) ) )  | 
						
						
							| 72 | 
							
								71
							 | 
							adantr | 
							 |-  ( ( w = <. a , t >. /\ <. a , t >. = <. <. x , y >. , z >. ) -> ( w = <. <. x , y >. , z >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> ph ) ) )  | 
						
						
							| 73 | 
							
								72
							 | 
							exlimivv | 
							 |-  ( E. a E. t ( w = <. a , t >. /\ <. a , t >. = <. <. x , y >. , z >. ) -> ( w = <. <. x , y >. , z >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> ph ) ) )  | 
						
						
							| 74 | 
							
								5 73
							 | 
							mpcom | 
							 |-  ( w = <. <. x , y >. , z >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> ph ) )  | 
						
						
							| 75 | 
							
								
							 | 
							19.8a | 
							 |-  ( ( w = <. <. x , y >. , z >. /\ ph ) -> E. z ( w = <. <. x , y >. , z >. /\ ph ) )  | 
						
						
							| 76 | 
							
								
							 | 
							19.8a | 
							 |-  ( E. z ( w = <. <. x , y >. , z >. /\ ph ) -> E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) )  | 
						
						
							| 77 | 
							
								
							 | 
							19.8a | 
							 |-  ( E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) -> E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) )  | 
						
						
							| 78 | 
							
								75 76 77
							 | 
							3syl | 
							 |-  ( ( w = <. <. x , y >. , z >. /\ ph ) -> E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) )  | 
						
						
							| 79 | 
							
								78
							 | 
							ex | 
							 |-  ( w = <. <. x , y >. , z >. -> ( ph -> E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) ) )  | 
						
						
							| 80 | 
							
								74 79
							 | 
							impbid | 
							 |-  ( w = <. <. x , y >. , z >. -> ( E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) <-> ph ) )  | 
						
						
							| 81 | 
							
								
							 | 
							df-oprab | 
							 |-  { <. <. x , y >. , z >. | ph } = { w | E. x E. y E. z ( w = <. <. x , y >. , z >. /\ ph ) } | 
						
						
							| 82 | 
							
								1 80 81
							 | 
							elab2 | 
							 |-  ( <. <. x , y >. , z >. e. { <. <. x , y >. , z >. | ph } <-> ph ) |