| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ecgrtg.1 |  |-  ( ph -> N e. NN ) | 
						
							| 2 |  | ecgrtg.2 |  |-  P = ( Base ` ( EEG ` N ) ) | 
						
							| 3 |  | ecgrtg.3 |  |-  .- = ( dist ` ( EEG ` N ) ) | 
						
							| 4 |  | ecgrtg.a |  |-  ( ph -> A e. P ) | 
						
							| 5 |  | ecgrtg.b |  |-  ( ph -> B e. P ) | 
						
							| 6 |  | ecgrtg.c |  |-  ( ph -> C e. P ) | 
						
							| 7 |  | ecgrtg.d |  |-  ( ph -> D e. P ) | 
						
							| 8 |  | eengbas |  |-  ( N e. NN -> ( EE ` N ) = ( Base ` ( EEG ` N ) ) ) | 
						
							| 9 | 1 8 | syl |  |-  ( ph -> ( EE ` N ) = ( Base ` ( EEG ` N ) ) ) | 
						
							| 10 | 9 2 | eqtr4di |  |-  ( ph -> ( EE ` N ) = P ) | 
						
							| 11 | 4 10 | eleqtrrd |  |-  ( ph -> A e. ( EE ` N ) ) | 
						
							| 12 | 5 10 | eleqtrrd |  |-  ( ph -> B e. ( EE ` N ) ) | 
						
							| 13 | 6 10 | eleqtrrd |  |-  ( ph -> C e. ( EE ` N ) ) | 
						
							| 14 | 7 10 | eleqtrrd |  |-  ( ph -> D e. ( EE ` N ) ) | 
						
							| 15 |  | brcgr |  |-  ( ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) -> ( <. A , B >. Cgr <. C , D >. <-> sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( D ` i ) ) ^ 2 ) ) ) | 
						
							| 16 | 11 12 13 14 15 | syl22anc |  |-  ( ph -> ( <. A , B >. Cgr <. C , D >. <-> sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( D ` i ) ) ^ 2 ) ) ) | 
						
							| 17 |  | dsid |  |-  dist = Slot ( dist ` ndx ) | 
						
							| 18 |  | fvexd |  |-  ( ph -> ( EEG ` N ) e. _V ) | 
						
							| 19 |  | eengstr |  |-  ( N e. NN -> ( EEG ` N ) Struct <. 1 , ; 1 7 >. ) | 
						
							| 20 | 1 19 | syl |  |-  ( ph -> ( EEG ` N ) Struct <. 1 , ; 1 7 >. ) | 
						
							| 21 |  | structn0fun |  |-  ( ( EEG ` N ) Struct <. 1 , ; 1 7 >. -> Fun ( ( EEG ` N ) \ { (/) } ) ) | 
						
							| 22 | 20 21 | syl |  |-  ( ph -> Fun ( ( EEG ` N ) \ { (/) } ) ) | 
						
							| 23 |  | structcnvcnv |  |-  ( ( EEG ` N ) Struct <. 1 , ; 1 7 >. -> `' `' ( EEG ` N ) = ( ( EEG ` N ) \ { (/) } ) ) | 
						
							| 24 | 20 23 | syl |  |-  ( ph -> `' `' ( EEG ` N ) = ( ( EEG ` N ) \ { (/) } ) ) | 
						
							| 25 | 24 | funeqd |  |-  ( ph -> ( Fun `' `' ( EEG ` N ) <-> Fun ( ( EEG ` N ) \ { (/) } ) ) ) | 
						
							| 26 | 22 25 | mpbird |  |-  ( ph -> Fun `' `' ( EEG ` N ) ) | 
						
							| 27 |  | opex |  |-  <. ( dist ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) >. e. _V | 
						
							| 28 | 27 | prid2 |  |-  <. ( dist ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) >. e. { <. ( Base ` ndx ) , ( EE ` N ) >. , <. ( dist ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) >. } | 
						
							| 29 |  | elun1 |  |-  ( <. ( dist ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) >. e. { <. ( Base ` ndx ) , ( EE ` N ) >. , <. ( dist ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) >. } -> <. ( dist ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) >. e. ( { <. ( Base ` ndx ) , ( EE ` N ) >. , <. ( dist ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) >. } u. { <. ( Itv ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) >. , <. ( LineG ` ndx ) , ( x e. ( EE ` N ) , y e. ( ( EE ` N ) \ { x } ) |-> { z e. ( EE ` N ) | ( z Btwn <. x , y >. \/ x Btwn <. z , y >. \/ y Btwn <. x , z >. ) } ) >. } ) ) | 
						
							| 30 | 28 29 | ax-mp |  |-  <. ( dist ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) >. e. ( { <. ( Base ` ndx ) , ( EE ` N ) >. , <. ( dist ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) >. } u. { <. ( Itv ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) >. , <. ( LineG ` ndx ) , ( x e. ( EE ` N ) , y e. ( ( EE ` N ) \ { x } ) |-> { z e. ( EE ` N ) | ( z Btwn <. x , y >. \/ x Btwn <. z , y >. \/ y Btwn <. x , z >. ) } ) >. } ) | 
						
							| 31 |  | eengv |  |-  ( N e. NN -> ( EEG ` N ) = ( { <. ( Base ` ndx ) , ( EE ` N ) >. , <. ( dist ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) >. } u. { <. ( Itv ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) >. , <. ( LineG ` ndx ) , ( x e. ( EE ` N ) , y e. ( ( EE ` N ) \ { x } ) |-> { z e. ( EE ` N ) | ( z Btwn <. x , y >. \/ x Btwn <. z , y >. \/ y Btwn <. x , z >. ) } ) >. } ) ) | 
						
							| 32 | 1 31 | syl |  |-  ( ph -> ( EEG ` N ) = ( { <. ( Base ` ndx ) , ( EE ` N ) >. , <. ( dist ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) >. } u. { <. ( Itv ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) >. , <. ( LineG ` ndx ) , ( x e. ( EE ` N ) , y e. ( ( EE ` N ) \ { x } ) |-> { z e. ( EE ` N ) | ( z Btwn <. x , y >. \/ x Btwn <. z , y >. \/ y Btwn <. x , z >. ) } ) >. } ) ) | 
						
							| 33 | 30 32 | eleqtrrid |  |-  ( ph -> <. ( dist ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) >. e. ( EEG ` N ) ) | 
						
							| 34 |  | fvex |  |-  ( EE ` N ) e. _V | 
						
							| 35 | 34 34 | mpoex |  |-  ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) e. _V | 
						
							| 36 | 35 | a1i |  |-  ( ph -> ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) e. _V ) | 
						
							| 37 | 17 18 26 33 36 | strfv2d |  |-  ( ph -> ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) = ( dist ` ( EEG ` N ) ) ) | 
						
							| 38 | 3 37 | eqtr4id |  |-  ( ph -> .- = ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) ) ) | 
						
							| 39 |  | simplrl |  |-  ( ( ( ph /\ ( x = A /\ y = B ) ) /\ i e. ( 1 ... N ) ) -> x = A ) | 
						
							| 40 | 39 | fveq1d |  |-  ( ( ( ph /\ ( x = A /\ y = B ) ) /\ i e. ( 1 ... N ) ) -> ( x ` i ) = ( A ` i ) ) | 
						
							| 41 |  | simplrr |  |-  ( ( ( ph /\ ( x = A /\ y = B ) ) /\ i e. ( 1 ... N ) ) -> y = B ) | 
						
							| 42 | 41 | fveq1d |  |-  ( ( ( ph /\ ( x = A /\ y = B ) ) /\ i e. ( 1 ... N ) ) -> ( y ` i ) = ( B ` i ) ) | 
						
							| 43 | 40 42 | oveq12d |  |-  ( ( ( ph /\ ( x = A /\ y = B ) ) /\ i e. ( 1 ... N ) ) -> ( ( x ` i ) - ( y ` i ) ) = ( ( A ` i ) - ( B ` i ) ) ) | 
						
							| 44 | 43 | oveq1d |  |-  ( ( ( ph /\ ( x = A /\ y = B ) ) /\ i e. ( 1 ... N ) ) -> ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) = ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) ) | 
						
							| 45 | 44 | sumeq2dv |  |-  ( ( ph /\ ( x = A /\ y = B ) ) -> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) ) | 
						
							| 46 |  | sumex |  |-  sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) e. _V | 
						
							| 47 | 46 | a1i |  |-  ( ph -> sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) e. _V ) | 
						
							| 48 | 38 45 11 12 47 | ovmpod |  |-  ( ph -> ( A .- B ) = sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) ) | 
						
							| 49 | 48 | eqcomd |  |-  ( ph -> sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = ( A .- B ) ) | 
						
							| 50 |  | simplrl |  |-  ( ( ( ph /\ ( x = C /\ y = D ) ) /\ i e. ( 1 ... N ) ) -> x = C ) | 
						
							| 51 | 50 | fveq1d |  |-  ( ( ( ph /\ ( x = C /\ y = D ) ) /\ i e. ( 1 ... N ) ) -> ( x ` i ) = ( C ` i ) ) | 
						
							| 52 |  | simplrr |  |-  ( ( ( ph /\ ( x = C /\ y = D ) ) /\ i e. ( 1 ... N ) ) -> y = D ) | 
						
							| 53 | 52 | fveq1d |  |-  ( ( ( ph /\ ( x = C /\ y = D ) ) /\ i e. ( 1 ... N ) ) -> ( y ` i ) = ( D ` i ) ) | 
						
							| 54 | 51 53 | oveq12d |  |-  ( ( ( ph /\ ( x = C /\ y = D ) ) /\ i e. ( 1 ... N ) ) -> ( ( x ` i ) - ( y ` i ) ) = ( ( C ` i ) - ( D ` i ) ) ) | 
						
							| 55 | 54 | oveq1d |  |-  ( ( ( ph /\ ( x = C /\ y = D ) ) /\ i e. ( 1 ... N ) ) -> ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) = ( ( ( C ` i ) - ( D ` i ) ) ^ 2 ) ) | 
						
							| 56 | 55 | sumeq2dv |  |-  ( ( ph /\ ( x = C /\ y = D ) ) -> sum_ i e. ( 1 ... N ) ( ( ( x ` i ) - ( y ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( D ` i ) ) ^ 2 ) ) | 
						
							| 57 |  | sumex |  |-  sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( D ` i ) ) ^ 2 ) e. _V | 
						
							| 58 | 57 | a1i |  |-  ( ph -> sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( D ` i ) ) ^ 2 ) e. _V ) | 
						
							| 59 | 38 56 13 14 58 | ovmpod |  |-  ( ph -> ( C .- D ) = sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( D ` i ) ) ^ 2 ) ) | 
						
							| 60 | 59 | eqcomd |  |-  ( ph -> sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( D ` i ) ) ^ 2 ) = ( C .- D ) ) | 
						
							| 61 | 49 60 | eqeq12d |  |-  ( ph -> ( sum_ i e. ( 1 ... N ) ( ( ( A ` i ) - ( B ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... N ) ( ( ( C ` i ) - ( D ` i ) ) ^ 2 ) <-> ( A .- B ) = ( C .- D ) ) ) | 
						
							| 62 | 16 61 | bitrd |  |-  ( ph -> ( <. A , B >. Cgr <. C , D >. <-> ( A .- B ) = ( C .- D ) ) ) |