| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							euotd.1 | 
							 |-  ( ph -> A e. U )  | 
						
						
							| 2 | 
							
								
							 | 
							euotd.2 | 
							 |-  ( ph -> B e. V )  | 
						
						
							| 3 | 
							
								
							 | 
							euotd.3 | 
							 |-  ( ph -> C e. W )  | 
						
						
							| 4 | 
							
								
							 | 
							euotd.4 | 
							 |-  ( ph -> ( ps <-> ( a = A /\ b = B /\ c = C ) ) )  | 
						
						
							| 5 | 
							
								4
							 | 
							biimpa | 
							 |-  ( ( ph /\ ps ) -> ( a = A /\ b = B /\ c = C ) )  | 
						
						
							| 6 | 
							
								
							 | 
							vex | 
							 |-  a e. _V  | 
						
						
							| 7 | 
							
								
							 | 
							vex | 
							 |-  b e. _V  | 
						
						
							| 8 | 
							
								
							 | 
							vex | 
							 |-  c e. _V  | 
						
						
							| 9 | 
							
								6 7 8
							 | 
							otth | 
							 |-  ( <. a , b , c >. = <. A , B , C >. <-> ( a = A /\ b = B /\ c = C ) )  | 
						
						
							| 10 | 
							
								5 9
							 | 
							sylibr | 
							 |-  ( ( ph /\ ps ) -> <. a , b , c >. = <. A , B , C >. )  | 
						
						
							| 11 | 
							
								10
							 | 
							eqeq2d | 
							 |-  ( ( ph /\ ps ) -> ( x = <. a , b , c >. <-> x = <. A , B , C >. ) )  | 
						
						
							| 12 | 
							
								11
							 | 
							biimpd | 
							 |-  ( ( ph /\ ps ) -> ( x = <. a , b , c >. -> x = <. A , B , C >. ) )  | 
						
						
							| 13 | 
							
								12
							 | 
							impancom | 
							 |-  ( ( ph /\ x = <. a , b , c >. ) -> ( ps -> x = <. A , B , C >. ) )  | 
						
						
							| 14 | 
							
								13
							 | 
							expimpd | 
							 |-  ( ph -> ( ( x = <. a , b , c >. /\ ps ) -> x = <. A , B , C >. ) )  | 
						
						
							| 15 | 
							
								14
							 | 
							exlimdv | 
							 |-  ( ph -> ( E. c ( x = <. a , b , c >. /\ ps ) -> x = <. A , B , C >. ) )  | 
						
						
							| 16 | 
							
								15
							 | 
							exlimdvv | 
							 |-  ( ph -> ( E. a E. b E. c ( x = <. a , b , c >. /\ ps ) -> x = <. A , B , C >. ) )  | 
						
						
							| 17 | 
							
								
							 | 
							tru | 
							 |-  T.  | 
						
						
							| 18 | 
							
								2
							 | 
							adantr | 
							 |-  ( ( ph /\ a = A ) -> B e. V )  | 
						
						
							| 19 | 
							
								3
							 | 
							ad2antrr | 
							 |-  ( ( ( ph /\ a = A ) /\ b = B ) -> C e. W )  | 
						
						
							| 20 | 
							
								
							 | 
							simpr | 
							 |-  ( ( ph /\ ( a = A /\ b = B /\ c = C ) ) -> ( a = A /\ b = B /\ c = C ) )  | 
						
						
							| 21 | 
							
								20 9
							 | 
							sylibr | 
							 |-  ( ( ph /\ ( a = A /\ b = B /\ c = C ) ) -> <. a , b , c >. = <. A , B , C >. )  | 
						
						
							| 22 | 
							
								21
							 | 
							eqcomd | 
							 |-  ( ( ph /\ ( a = A /\ b = B /\ c = C ) ) -> <. A , B , C >. = <. a , b , c >. )  | 
						
						
							| 23 | 
							
								4
							 | 
							biimpar | 
							 |-  ( ( ph /\ ( a = A /\ b = B /\ c = C ) ) -> ps )  | 
						
						
							| 24 | 
							
								22 23
							 | 
							jca | 
							 |-  ( ( ph /\ ( a = A /\ b = B /\ c = C ) ) -> ( <. A , B , C >. = <. a , b , c >. /\ ps ) )  | 
						
						
							| 25 | 
							
								
							 | 
							trud | 
							 |-  ( ( ph /\ ( a = A /\ b = B /\ c = C ) ) -> T. )  | 
						
						
							| 26 | 
							
								24 25
							 | 
							2thd | 
							 |-  ( ( ph /\ ( a = A /\ b = B /\ c = C ) ) -> ( ( <. A , B , C >. = <. a , b , c >. /\ ps ) <-> T. ) )  | 
						
						
							| 27 | 
							
								26
							 | 
							3anassrs | 
							 |-  ( ( ( ( ph /\ a = A ) /\ b = B ) /\ c = C ) -> ( ( <. A , B , C >. = <. a , b , c >. /\ ps ) <-> T. ) )  | 
						
						
							| 28 | 
							
								19 27
							 | 
							sbcied | 
							 |-  ( ( ( ph /\ a = A ) /\ b = B ) -> ( [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) <-> T. ) )  | 
						
						
							| 29 | 
							
								18 28
							 | 
							sbcied | 
							 |-  ( ( ph /\ a = A ) -> ( [. B / b ]. [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) <-> T. ) )  | 
						
						
							| 30 | 
							
								1 29
							 | 
							sbcied | 
							 |-  ( ph -> ( [. A / a ]. [. B / b ]. [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) <-> T. ) )  | 
						
						
							| 31 | 
							
								17 30
							 | 
							mpbiri | 
							 |-  ( ph -> [. A / a ]. [. B / b ]. [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) )  | 
						
						
							| 32 | 
							
								31
							 | 
							spesbcd | 
							 |-  ( ph -> E. a [. B / b ]. [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) )  | 
						
						
							| 33 | 
							
								
							 | 
							nfcv | 
							 |-  F/_ b B  | 
						
						
							| 34 | 
							
								
							 | 
							nfsbc1v | 
							 |-  F/ b [. B / b ]. [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps )  | 
						
						
							| 35 | 
							
								34
							 | 
							nfex | 
							 |-  F/ b E. a [. B / b ]. [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps )  | 
						
						
							| 36 | 
							
								
							 | 
							sbceq1a | 
							 |-  ( b = B -> ( [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) <-> [. B / b ]. [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) ) )  | 
						
						
							| 37 | 
							
								36
							 | 
							exbidv | 
							 |-  ( b = B -> ( E. a [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) <-> E. a [. B / b ]. [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) ) )  | 
						
						
							| 38 | 
							
								33 35 37
							 | 
							spcegf | 
							 |-  ( B e. V -> ( E. a [. B / b ]. [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) -> E. b E. a [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) ) )  | 
						
						
							| 39 | 
							
								2 32 38
							 | 
							sylc | 
							 |-  ( ph -> E. b E. a [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) )  | 
						
						
							| 40 | 
							
								
							 | 
							nfcv | 
							 |-  F/_ c C  | 
						
						
							| 41 | 
							
								
							 | 
							nfsbc1v | 
							 |-  F/ c [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps )  | 
						
						
							| 42 | 
							
								41
							 | 
							nfex | 
							 |-  F/ c E. a [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps )  | 
						
						
							| 43 | 
							
								42
							 | 
							nfex | 
							 |-  F/ c E. b E. a [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps )  | 
						
						
							| 44 | 
							
								
							 | 
							sbceq1a | 
							 |-  ( c = C -> ( ( <. A , B , C >. = <. a , b , c >. /\ ps ) <-> [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) ) )  | 
						
						
							| 45 | 
							
								44
							 | 
							2exbidv | 
							 |-  ( c = C -> ( E. b E. a ( <. A , B , C >. = <. a , b , c >. /\ ps ) <-> E. b E. a [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) ) )  | 
						
						
							| 46 | 
							
								40 43 45
							 | 
							spcegf | 
							 |-  ( C e. W -> ( E. b E. a [. C / c ]. ( <. A , B , C >. = <. a , b , c >. /\ ps ) -> E. c E. b E. a ( <. A , B , C >. = <. a , b , c >. /\ ps ) ) )  | 
						
						
							| 47 | 
							
								3 39 46
							 | 
							sylc | 
							 |-  ( ph -> E. c E. b E. a ( <. A , B , C >. = <. a , b , c >. /\ ps ) )  | 
						
						
							| 48 | 
							
								
							 | 
							excom13 | 
							 |-  ( E. c E. b E. a ( <. A , B , C >. = <. a , b , c >. /\ ps ) <-> E. a E. b E. c ( <. A , B , C >. = <. a , b , c >. /\ ps ) )  | 
						
						
							| 49 | 
							
								47 48
							 | 
							sylib | 
							 |-  ( ph -> E. a E. b E. c ( <. A , B , C >. = <. a , b , c >. /\ ps ) )  | 
						
						
							| 50 | 
							
								
							 | 
							eqeq1 | 
							 |-  ( x = <. A , B , C >. -> ( x = <. a , b , c >. <-> <. A , B , C >. = <. a , b , c >. ) )  | 
						
						
							| 51 | 
							
								50
							 | 
							anbi1d | 
							 |-  ( x = <. A , B , C >. -> ( ( x = <. a , b , c >. /\ ps ) <-> ( <. A , B , C >. = <. a , b , c >. /\ ps ) ) )  | 
						
						
							| 52 | 
							
								51
							 | 
							3exbidv | 
							 |-  ( x = <. A , B , C >. -> ( E. a E. b E. c ( x = <. a , b , c >. /\ ps ) <-> E. a E. b E. c ( <. A , B , C >. = <. a , b , c >. /\ ps ) ) )  | 
						
						
							| 53 | 
							
								49 52
							 | 
							syl5ibrcom | 
							 |-  ( ph -> ( x = <. A , B , C >. -> E. a E. b E. c ( x = <. a , b , c >. /\ ps ) ) )  | 
						
						
							| 54 | 
							
								16 53
							 | 
							impbid | 
							 |-  ( ph -> ( E. a E. b E. c ( x = <. a , b , c >. /\ ps ) <-> x = <. A , B , C >. ) )  | 
						
						
							| 55 | 
							
								54
							 | 
							alrimiv | 
							 |-  ( ph -> A. x ( E. a E. b E. c ( x = <. a , b , c >. /\ ps ) <-> x = <. A , B , C >. ) )  | 
						
						
							| 56 | 
							
								
							 | 
							otex | 
							 |-  <. A , B , C >. e. _V  | 
						
						
							| 57 | 
							
								
							 | 
							eqeq2 | 
							 |-  ( y = <. A , B , C >. -> ( x = y <-> x = <. A , B , C >. ) )  | 
						
						
							| 58 | 
							
								57
							 | 
							bibi2d | 
							 |-  ( y = <. A , B , C >. -> ( ( E. a E. b E. c ( x = <. a , b , c >. /\ ps ) <-> x = y ) <-> ( E. a E. b E. c ( x = <. a , b , c >. /\ ps ) <-> x = <. A , B , C >. ) ) )  | 
						
						
							| 59 | 
							
								58
							 | 
							albidv | 
							 |-  ( y = <. A , B , C >. -> ( A. x ( E. a E. b E. c ( x = <. a , b , c >. /\ ps ) <-> x = y ) <-> A. x ( E. a E. b E. c ( x = <. a , b , c >. /\ ps ) <-> x = <. A , B , C >. ) ) )  | 
						
						
							| 60 | 
							
								56 59
							 | 
							spcev | 
							 |-  ( A. x ( E. a E. b E. c ( x = <. a , b , c >. /\ ps ) <-> x = <. A , B , C >. ) -> E. y A. x ( E. a E. b E. c ( x = <. a , b , c >. /\ ps ) <-> x = y ) )  | 
						
						
							| 61 | 
							
								55 60
							 | 
							syl | 
							 |-  ( ph -> E. y A. x ( E. a E. b E. c ( x = <. a , b , c >. /\ ps ) <-> x = y ) )  | 
						
						
							| 62 | 
							
								
							 | 
							eu6 | 
							 |-  ( E! x E. a E. b E. c ( x = <. a , b , c >. /\ ps ) <-> E. y A. x ( E. a E. b E. c ( x = <. a , b , c >. /\ ps ) <-> x = y ) )  | 
						
						
							| 63 | 
							
								61 62
							 | 
							sylibr | 
							 |-  ( ph -> E! x E. a E. b E. c ( x = <. a , b , c >. /\ ps ) )  |