| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ebtwntg.1 |  |-  ( ph -> N e. NN ) | 
						
							| 2 |  | ebtwntg.2 |  |-  P = ( Base ` ( EEG ` N ) ) | 
						
							| 3 |  | ebtwntg.3 |  |-  I = ( Itv ` ( EEG ` N ) ) | 
						
							| 4 |  | ebtwntg.x |  |-  ( ph -> X e. P ) | 
						
							| 5 |  | ebtwntg.y |  |-  ( ph -> Y e. P ) | 
						
							| 6 |  | ebtwntg.z |  |-  ( ph -> Z e. P ) | 
						
							| 7 |  | itvid |  |-  Itv = Slot ( Itv ` ndx ) | 
						
							| 8 |  | fvexd |  |-  ( ph -> ( EEG ` N ) e. _V ) | 
						
							| 9 |  | eengstr |  |-  ( N e. NN -> ( EEG ` N ) Struct <. 1 , ; 1 7 >. ) | 
						
							| 10 | 1 9 | syl |  |-  ( ph -> ( EEG ` N ) Struct <. 1 , ; 1 7 >. ) | 
						
							| 11 |  | structn0fun |  |-  ( ( EEG ` N ) Struct <. 1 , ; 1 7 >. -> Fun ( ( EEG ` N ) \ { (/) } ) ) | 
						
							| 12 | 10 11 | syl |  |-  ( ph -> Fun ( ( EEG ` N ) \ { (/) } ) ) | 
						
							| 13 |  | structcnvcnv |  |-  ( ( EEG ` N ) Struct <. 1 , ; 1 7 >. -> `' `' ( EEG ` N ) = ( ( EEG ` N ) \ { (/) } ) ) | 
						
							| 14 | 10 13 | syl |  |-  ( ph -> `' `' ( EEG ` N ) = ( ( EEG ` N ) \ { (/) } ) ) | 
						
							| 15 | 14 | funeqd |  |-  ( ph -> ( Fun `' `' ( EEG ` N ) <-> Fun ( ( EEG ` N ) \ { (/) } ) ) ) | 
						
							| 16 | 12 15 | mpbird |  |-  ( ph -> Fun `' `' ( EEG ` N ) ) | 
						
							| 17 |  | opex |  |-  <. ( Itv ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) >. e. _V | 
						
							| 18 | 17 | prid1 |  |-  <. ( Itv ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) >. e. { <. ( 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 >. ) } ) >. } | 
						
							| 19 |  | elun2 |  |-  ( <. ( Itv ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) >. e. { <. ( 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 >. ) } ) >. } -> <. ( Itv ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) >. 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 >. ) } ) >. } ) ) | 
						
							| 20 | 18 19 | ax-mp |  |-  <. ( Itv ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) >. 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 >. ) } ) >. } ) | 
						
							| 21 |  | 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 >. ) } ) >. } ) ) | 
						
							| 22 | 1 21 | 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 >. ) } ) >. } ) ) | 
						
							| 23 | 20 22 | eleqtrrid |  |-  ( ph -> <. ( Itv ` ndx ) , ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) >. e. ( EEG ` N ) ) | 
						
							| 24 |  | fvex |  |-  ( EE ` N ) e. _V | 
						
							| 25 | 24 24 | mpoex |  |-  ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) e. _V | 
						
							| 26 | 25 | a1i |  |-  ( ph -> ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) e. _V ) | 
						
							| 27 | 7 8 16 23 26 | strfv2d |  |-  ( ph -> ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) = ( Itv ` ( EEG ` N ) ) ) | 
						
							| 28 | 3 27 | eqtr4id |  |-  ( ph -> I = ( x e. ( EE ` N ) , y e. ( EE ` N ) |-> { z e. ( EE ` N ) | z Btwn <. x , y >. } ) ) | 
						
							| 29 |  | simprl |  |-  ( ( ph /\ ( x = X /\ y = Y ) ) -> x = X ) | 
						
							| 30 |  | simprr |  |-  ( ( ph /\ ( x = X /\ y = Y ) ) -> y = Y ) | 
						
							| 31 | 29 30 | opeq12d |  |-  ( ( ph /\ ( x = X /\ y = Y ) ) -> <. x , y >. = <. X , Y >. ) | 
						
							| 32 | 31 | breq2d |  |-  ( ( ph /\ ( x = X /\ y = Y ) ) -> ( z Btwn <. x , y >. <-> z Btwn <. X , Y >. ) ) | 
						
							| 33 | 32 | rabbidv |  |-  ( ( ph /\ ( x = X /\ y = Y ) ) -> { z e. ( EE ` N ) | z Btwn <. x , y >. } = { z e. ( EE ` N ) | z Btwn <. X , Y >. } ) | 
						
							| 34 | 4 2 | eleqtrdi |  |-  ( ph -> X e. ( Base ` ( EEG ` N ) ) ) | 
						
							| 35 |  | eengbas |  |-  ( N e. NN -> ( EE ` N ) = ( Base ` ( EEG ` N ) ) ) | 
						
							| 36 | 1 35 | syl |  |-  ( ph -> ( EE ` N ) = ( Base ` ( EEG ` N ) ) ) | 
						
							| 37 | 34 36 | eleqtrrd |  |-  ( ph -> X e. ( EE ` N ) ) | 
						
							| 38 | 5 2 | eleqtrdi |  |-  ( ph -> Y e. ( Base ` ( EEG ` N ) ) ) | 
						
							| 39 | 38 36 | eleqtrrd |  |-  ( ph -> Y e. ( EE ` N ) ) | 
						
							| 40 | 24 | rabex |  |-  { z e. ( EE ` N ) | z Btwn <. X , Y >. } e. _V | 
						
							| 41 | 40 | a1i |  |-  ( ph -> { z e. ( EE ` N ) | z Btwn <. X , Y >. } e. _V ) | 
						
							| 42 | 28 33 37 39 41 | ovmpod |  |-  ( ph -> ( X I Y ) = { z e. ( EE ` N ) | z Btwn <. X , Y >. } ) | 
						
							| 43 | 42 | eleq2d |  |-  ( ph -> ( Z e. ( X I Y ) <-> Z e. { z e. ( EE ` N ) | z Btwn <. X , Y >. } ) ) | 
						
							| 44 | 6 2 | eleqtrdi |  |-  ( ph -> Z e. ( Base ` ( EEG ` N ) ) ) | 
						
							| 45 | 44 36 | eleqtrrd |  |-  ( ph -> Z e. ( EE ` N ) ) | 
						
							| 46 |  | breq1 |  |-  ( z = Z -> ( z Btwn <. X , Y >. <-> Z Btwn <. X , Y >. ) ) | 
						
							| 47 | 46 | elrab3 |  |-  ( Z e. ( EE ` N ) -> ( Z e. { z e. ( EE ` N ) | z Btwn <. X , Y >. } <-> Z Btwn <. X , Y >. ) ) | 
						
							| 48 | 45 47 | syl |  |-  ( ph -> ( Z e. { z e. ( EE ` N ) | z Btwn <. X , Y >. } <-> Z Btwn <. X , Y >. ) ) | 
						
							| 49 | 43 48 | bitr2d |  |-  ( ph -> ( Z Btwn <. X , Y >. <-> Z e. ( X I Y ) ) ) |