| Step | Hyp | Ref | Expression | 
						
							| 1 |  | fsumsers.1 |  |-  ( ( ph /\ k e. ( ZZ>= ` M ) ) -> ( F ` k ) = if ( k e. A , B , 0 ) ) | 
						
							| 2 |  | fsumsers.2 |  |-  ( ph -> N e. ( ZZ>= ` M ) ) | 
						
							| 3 |  | fsumsers.3 |  |-  ( ( ph /\ k e. A ) -> B e. CC ) | 
						
							| 4 |  | fsumsers.4 |  |-  ( ph -> A C_ ( M ... N ) ) | 
						
							| 5 |  | eqid |  |-  ( ZZ>= ` M ) = ( ZZ>= ` M ) | 
						
							| 6 |  | eluzel2 |  |-  ( N e. ( ZZ>= ` M ) -> M e. ZZ ) | 
						
							| 7 | 2 6 | syl |  |-  ( ph -> M e. ZZ ) | 
						
							| 8 |  | fzssuz |  |-  ( M ... N ) C_ ( ZZ>= ` M ) | 
						
							| 9 | 4 8 | sstrdi |  |-  ( ph -> A C_ ( ZZ>= ` M ) ) | 
						
							| 10 | 5 7 9 1 3 | zsum |  |-  ( ph -> sum_ k e. A B = ( ~~> ` seq M ( + , F ) ) ) | 
						
							| 11 |  | fclim |  |-  ~~> : dom ~~> --> CC | 
						
							| 12 |  | ffun |  |-  ( ~~> : dom ~~> --> CC -> Fun ~~> ) | 
						
							| 13 | 11 12 | ax-mp |  |-  Fun ~~> | 
						
							| 14 | 1 2 3 4 | fsumcvg2 |  |-  ( ph -> seq M ( + , F ) ~~> ( seq M ( + , F ) ` N ) ) | 
						
							| 15 |  | funbrfv |  |-  ( Fun ~~> -> ( seq M ( + , F ) ~~> ( seq M ( + , F ) ` N ) -> ( ~~> ` seq M ( + , F ) ) = ( seq M ( + , F ) ` N ) ) ) | 
						
							| 16 | 13 14 15 | mpsyl |  |-  ( ph -> ( ~~> ` seq M ( + , F ) ) = ( seq M ( + , F ) ` N ) ) | 
						
							| 17 | 10 16 | eqtrd |  |-  ( ph -> sum_ k e. A B = ( seq M ( + , F ) ` N ) ) |