| Step | Hyp | Ref | Expression | 
						
							| 1 |  | eqid |  |-  ( j e. NN |-> ( 2 ^ -u ( ! ` j ) ) ) = ( j e. NN |-> ( 2 ^ -u ( ! ` j ) ) ) | 
						
							| 2 |  | fveq2 |  |-  ( k = i -> ( ! ` k ) = ( ! ` i ) ) | 
						
							| 3 | 2 | negeqd |  |-  ( k = i -> -u ( ! ` k ) = -u ( ! ` i ) ) | 
						
							| 4 | 3 | oveq2d |  |-  ( k = i -> ( 2 ^ -u ( ! ` k ) ) = ( 2 ^ -u ( ! ` i ) ) ) | 
						
							| 5 | 4 | cbvsumv |  |-  sum_ k e. NN ( 2 ^ -u ( ! ` k ) ) = sum_ i e. NN ( 2 ^ -u ( ! ` i ) ) | 
						
							| 6 |  | fveq2 |  |-  ( j = i -> ( ! ` j ) = ( ! ` i ) ) | 
						
							| 7 | 6 | negeqd |  |-  ( j = i -> -u ( ! ` j ) = -u ( ! ` i ) ) | 
						
							| 8 | 7 | oveq2d |  |-  ( j = i -> ( 2 ^ -u ( ! ` j ) ) = ( 2 ^ -u ( ! ` i ) ) ) | 
						
							| 9 |  | ovex |  |-  ( 2 ^ -u ( ! ` i ) ) e. _V | 
						
							| 10 | 8 1 9 | fvmpt |  |-  ( i e. NN -> ( ( j e. NN |-> ( 2 ^ -u ( ! ` j ) ) ) ` i ) = ( 2 ^ -u ( ! ` i ) ) ) | 
						
							| 11 | 10 | eqcomd |  |-  ( i e. NN -> ( 2 ^ -u ( ! ` i ) ) = ( ( j e. NN |-> ( 2 ^ -u ( ! ` j ) ) ) ` i ) ) | 
						
							| 12 | 11 | sumeq2i |  |-  sum_ i e. NN ( 2 ^ -u ( ! ` i ) ) = sum_ i e. NN ( ( j e. NN |-> ( 2 ^ -u ( ! ` j ) ) ) ` i ) | 
						
							| 13 | 5 12 | eqtri |  |-  sum_ k e. NN ( 2 ^ -u ( ! ` k ) ) = sum_ i e. NN ( ( j e. NN |-> ( 2 ^ -u ( ! ` j ) ) ) ` i ) | 
						
							| 14 |  | eqid |  |-  ( l e. NN |-> sum_ i e. ( 1 ... l ) ( ( j e. NN |-> ( 2 ^ -u ( ! ` j ) ) ) ` i ) ) = ( l e. NN |-> sum_ i e. ( 1 ... l ) ( ( j e. NN |-> ( 2 ^ -u ( ! ` j ) ) ) ` i ) ) | 
						
							| 15 | 1 13 14 | aaliou3lem9 |  |-  -. sum_ k e. NN ( 2 ^ -u ( ! ` k ) ) e. AA | 
						
							| 16 | 15 | nelir |  |-  sum_ k e. NN ( 2 ^ -u ( ! ` k ) ) e/ AA |