| Step | Hyp | Ref | Expression | 
						
							| 0 |  | ccgr |  |-  Cgr | 
						
							| 1 |  | vx |  |-  x | 
						
							| 2 |  | vy |  |-  y | 
						
							| 3 |  | vn |  |-  n | 
						
							| 4 |  | cn |  |-  NN | 
						
							| 5 | 1 | cv |  |-  x | 
						
							| 6 |  | cee |  |-  EE | 
						
							| 7 | 3 | cv |  |-  n | 
						
							| 8 | 7 6 | cfv |  |-  ( EE ` n ) | 
						
							| 9 | 8 8 | cxp |  |-  ( ( EE ` n ) X. ( EE ` n ) ) | 
						
							| 10 | 5 9 | wcel |  |-  x e. ( ( EE ` n ) X. ( EE ` n ) ) | 
						
							| 11 | 2 | cv |  |-  y | 
						
							| 12 | 11 9 | wcel |  |-  y e. ( ( EE ` n ) X. ( EE ` n ) ) | 
						
							| 13 | 10 12 | wa |  |-  ( x e. ( ( EE ` n ) X. ( EE ` n ) ) /\ y e. ( ( EE ` n ) X. ( EE ` n ) ) ) | 
						
							| 14 |  | vi |  |-  i | 
						
							| 15 |  | c1 |  |-  1 | 
						
							| 16 |  | cfz |  |-  ... | 
						
							| 17 | 15 7 16 | co |  |-  ( 1 ... n ) | 
						
							| 18 |  | c1st |  |-  1st | 
						
							| 19 | 5 18 | cfv |  |-  ( 1st ` x ) | 
						
							| 20 | 14 | cv |  |-  i | 
						
							| 21 | 20 19 | cfv |  |-  ( ( 1st ` x ) ` i ) | 
						
							| 22 |  | cmin |  |-  - | 
						
							| 23 |  | c2nd |  |-  2nd | 
						
							| 24 | 5 23 | cfv |  |-  ( 2nd ` x ) | 
						
							| 25 | 20 24 | cfv |  |-  ( ( 2nd ` x ) ` i ) | 
						
							| 26 | 21 25 22 | co |  |-  ( ( ( 1st ` x ) ` i ) - ( ( 2nd ` x ) ` i ) ) | 
						
							| 27 |  | cexp |  |-  ^ | 
						
							| 28 |  | c2 |  |-  2 | 
						
							| 29 | 26 28 27 | co |  |-  ( ( ( ( 1st ` x ) ` i ) - ( ( 2nd ` x ) ` i ) ) ^ 2 ) | 
						
							| 30 | 17 29 14 | csu |  |-  sum_ i e. ( 1 ... n ) ( ( ( ( 1st ` x ) ` i ) - ( ( 2nd ` x ) ` i ) ) ^ 2 ) | 
						
							| 31 | 11 18 | cfv |  |-  ( 1st ` y ) | 
						
							| 32 | 20 31 | cfv |  |-  ( ( 1st ` y ) ` i ) | 
						
							| 33 | 11 23 | cfv |  |-  ( 2nd ` y ) | 
						
							| 34 | 20 33 | cfv |  |-  ( ( 2nd ` y ) ` i ) | 
						
							| 35 | 32 34 22 | co |  |-  ( ( ( 1st ` y ) ` i ) - ( ( 2nd ` y ) ` i ) ) | 
						
							| 36 | 35 28 27 | co |  |-  ( ( ( ( 1st ` y ) ` i ) - ( ( 2nd ` y ) ` i ) ) ^ 2 ) | 
						
							| 37 | 17 36 14 | csu |  |-  sum_ i e. ( 1 ... n ) ( ( ( ( 1st ` y ) ` i ) - ( ( 2nd ` y ) ` i ) ) ^ 2 ) | 
						
							| 38 | 30 37 | wceq |  |-  sum_ i e. ( 1 ... n ) ( ( ( ( 1st ` x ) ` i ) - ( ( 2nd ` x ) ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... n ) ( ( ( ( 1st ` y ) ` i ) - ( ( 2nd ` y ) ` i ) ) ^ 2 ) | 
						
							| 39 | 13 38 | wa |  |-  ( ( x e. ( ( EE ` n ) X. ( EE ` n ) ) /\ y e. ( ( EE ` n ) X. ( EE ` n ) ) ) /\ sum_ i e. ( 1 ... n ) ( ( ( ( 1st ` x ) ` i ) - ( ( 2nd ` x ) ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... n ) ( ( ( ( 1st ` y ) ` i ) - ( ( 2nd ` y ) ` i ) ) ^ 2 ) ) | 
						
							| 40 | 39 3 4 | wrex |  |-  E. n e. NN ( ( x e. ( ( EE ` n ) X. ( EE ` n ) ) /\ y e. ( ( EE ` n ) X. ( EE ` n ) ) ) /\ sum_ i e. ( 1 ... n ) ( ( ( ( 1st ` x ) ` i ) - ( ( 2nd ` x ) ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... n ) ( ( ( ( 1st ` y ) ` i ) - ( ( 2nd ` y ) ` i ) ) ^ 2 ) ) | 
						
							| 41 | 40 1 2 | copab |  |-  { <. x , y >. | E. n e. NN ( ( x e. ( ( EE ` n ) X. ( EE ` n ) ) /\ y e. ( ( EE ` n ) X. ( EE ` n ) ) ) /\ sum_ i e. ( 1 ... n ) ( ( ( ( 1st ` x ) ` i ) - ( ( 2nd ` x ) ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... n ) ( ( ( ( 1st ` y ) ` i ) - ( ( 2nd ` y ) ` i ) ) ^ 2 ) ) } | 
						
							| 42 | 0 41 | wceq |  |-  Cgr = { <. x , y >. | E. n e. NN ( ( x e. ( ( EE ` n ) X. ( EE ` n ) ) /\ y e. ( ( EE ` n ) X. ( EE ` n ) ) ) /\ sum_ i e. ( 1 ... n ) ( ( ( ( 1st ` x ) ` i ) - ( ( 2nd ` x ) ` i ) ) ^ 2 ) = sum_ i e. ( 1 ... n ) ( ( ( ( 1st ` y ) ` i ) - ( ( 2nd ` y ) ` i ) ) ^ 2 ) ) } |