| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 0z |  |-  0 e. ZZ | 
						
							| 2 |  | fzrevral |  |-  ( ( M e. ZZ /\ N e. ZZ /\ 0 e. ZZ ) -> ( A. j e. ( M ... N ) ph <-> A. x e. ( ( 0 - N ) ... ( 0 - M ) ) [. ( 0 - x ) / j ]. ph ) ) | 
						
							| 3 | 1 2 | mp3an3 |  |-  ( ( M e. ZZ /\ N e. ZZ ) -> ( A. j e. ( M ... N ) ph <-> A. x e. ( ( 0 - N ) ... ( 0 - M ) ) [. ( 0 - x ) / j ]. ph ) ) | 
						
							| 4 | 3 | 3adant3 |  |-  ( ( M e. ZZ /\ N e. ZZ /\ K e. ZZ ) -> ( A. j e. ( M ... N ) ph <-> A. x e. ( ( 0 - N ) ... ( 0 - M ) ) [. ( 0 - x ) / j ]. ph ) ) | 
						
							| 5 |  | zsubcl |  |-  ( ( 0 e. ZZ /\ N e. ZZ ) -> ( 0 - N ) e. ZZ ) | 
						
							| 6 | 1 5 | mpan |  |-  ( N e. ZZ -> ( 0 - N ) e. ZZ ) | 
						
							| 7 |  | zsubcl |  |-  ( ( 0 e. ZZ /\ M e. ZZ ) -> ( 0 - M ) e. ZZ ) | 
						
							| 8 | 1 7 | mpan |  |-  ( M e. ZZ -> ( 0 - M ) e. ZZ ) | 
						
							| 9 |  | id |  |-  ( K e. ZZ -> K e. ZZ ) | 
						
							| 10 |  | fzrevral |  |-  ( ( ( 0 - N ) e. ZZ /\ ( 0 - M ) e. ZZ /\ K e. ZZ ) -> ( A. x e. ( ( 0 - N ) ... ( 0 - M ) ) [. ( 0 - x ) / j ]. ph <-> A. k e. ( ( K - ( 0 - M ) ) ... ( K - ( 0 - N ) ) ) [. ( K - k ) / x ]. [. ( 0 - x ) / j ]. ph ) ) | 
						
							| 11 | 6 8 9 10 | syl3an |  |-  ( ( N e. ZZ /\ M e. ZZ /\ K e. ZZ ) -> ( A. x e. ( ( 0 - N ) ... ( 0 - M ) ) [. ( 0 - x ) / j ]. ph <-> A. k e. ( ( K - ( 0 - M ) ) ... ( K - ( 0 - N ) ) ) [. ( K - k ) / x ]. [. ( 0 - x ) / j ]. ph ) ) | 
						
							| 12 | 11 | 3com12 |  |-  ( ( M e. ZZ /\ N e. ZZ /\ K e. ZZ ) -> ( A. x e. ( ( 0 - N ) ... ( 0 - M ) ) [. ( 0 - x ) / j ]. ph <-> A. k e. ( ( K - ( 0 - M ) ) ... ( K - ( 0 - N ) ) ) [. ( K - k ) / x ]. [. ( 0 - x ) / j ]. ph ) ) | 
						
							| 13 |  | ovex |  |-  ( K - k ) e. _V | 
						
							| 14 |  | oveq2 |  |-  ( x = ( K - k ) -> ( 0 - x ) = ( 0 - ( K - k ) ) ) | 
						
							| 15 | 14 | sbcco3gw |  |-  ( ( K - k ) e. _V -> ( [. ( K - k ) / x ]. [. ( 0 - x ) / j ]. ph <-> [. ( 0 - ( K - k ) ) / j ]. ph ) ) | 
						
							| 16 | 13 15 | ax-mp |  |-  ( [. ( K - k ) / x ]. [. ( 0 - x ) / j ]. ph <-> [. ( 0 - ( K - k ) ) / j ]. ph ) | 
						
							| 17 | 16 | ralbii |  |-  ( A. k e. ( ( K - ( 0 - M ) ) ... ( K - ( 0 - N ) ) ) [. ( K - k ) / x ]. [. ( 0 - x ) / j ]. ph <-> A. k e. ( ( K - ( 0 - M ) ) ... ( K - ( 0 - N ) ) ) [. ( 0 - ( K - k ) ) / j ]. ph ) | 
						
							| 18 |  | zcn |  |-  ( M e. ZZ -> M e. CC ) | 
						
							| 19 |  | zcn |  |-  ( N e. ZZ -> N e. CC ) | 
						
							| 20 |  | zcn |  |-  ( K e. ZZ -> K e. CC ) | 
						
							| 21 |  | df-neg |  |-  -u M = ( 0 - M ) | 
						
							| 22 | 21 | oveq2i |  |-  ( K - -u M ) = ( K - ( 0 - M ) ) | 
						
							| 23 |  | subneg |  |-  ( ( K e. CC /\ M e. CC ) -> ( K - -u M ) = ( K + M ) ) | 
						
							| 24 |  | addcom |  |-  ( ( K e. CC /\ M e. CC ) -> ( K + M ) = ( M + K ) ) | 
						
							| 25 | 23 24 | eqtrd |  |-  ( ( K e. CC /\ M e. CC ) -> ( K - -u M ) = ( M + K ) ) | 
						
							| 26 | 22 25 | eqtr3id |  |-  ( ( K e. CC /\ M e. CC ) -> ( K - ( 0 - M ) ) = ( M + K ) ) | 
						
							| 27 | 26 | 3adant3 |  |-  ( ( K e. CC /\ M e. CC /\ N e. CC ) -> ( K - ( 0 - M ) ) = ( M + K ) ) | 
						
							| 28 |  | df-neg |  |-  -u N = ( 0 - N ) | 
						
							| 29 | 28 | oveq2i |  |-  ( K - -u N ) = ( K - ( 0 - N ) ) | 
						
							| 30 |  | subneg |  |-  ( ( K e. CC /\ N e. CC ) -> ( K - -u N ) = ( K + N ) ) | 
						
							| 31 |  | addcom |  |-  ( ( K e. CC /\ N e. CC ) -> ( K + N ) = ( N + K ) ) | 
						
							| 32 | 30 31 | eqtrd |  |-  ( ( K e. CC /\ N e. CC ) -> ( K - -u N ) = ( N + K ) ) | 
						
							| 33 | 29 32 | eqtr3id |  |-  ( ( K e. CC /\ N e. CC ) -> ( K - ( 0 - N ) ) = ( N + K ) ) | 
						
							| 34 | 33 | 3adant2 |  |-  ( ( K e. CC /\ M e. CC /\ N e. CC ) -> ( K - ( 0 - N ) ) = ( N + K ) ) | 
						
							| 35 | 27 34 | oveq12d |  |-  ( ( K e. CC /\ M e. CC /\ N e. CC ) -> ( ( K - ( 0 - M ) ) ... ( K - ( 0 - N ) ) ) = ( ( M + K ) ... ( N + K ) ) ) | 
						
							| 36 | 35 | 3coml |  |-  ( ( M e. CC /\ N e. CC /\ K e. CC ) -> ( ( K - ( 0 - M ) ) ... ( K - ( 0 - N ) ) ) = ( ( M + K ) ... ( N + K ) ) ) | 
						
							| 37 | 18 19 20 36 | syl3an |  |-  ( ( M e. ZZ /\ N e. ZZ /\ K e. ZZ ) -> ( ( K - ( 0 - M ) ) ... ( K - ( 0 - N ) ) ) = ( ( M + K ) ... ( N + K ) ) ) | 
						
							| 38 | 37 | raleqdv |  |-  ( ( M e. ZZ /\ N e. ZZ /\ K e. ZZ ) -> ( A. k e. ( ( K - ( 0 - M ) ) ... ( K - ( 0 - N ) ) ) [. ( 0 - ( K - k ) ) / j ]. ph <-> A. k e. ( ( M + K ) ... ( N + K ) ) [. ( 0 - ( K - k ) ) / j ]. ph ) ) | 
						
							| 39 |  | elfzelz |  |-  ( k e. ( ( M + K ) ... ( N + K ) ) -> k e. ZZ ) | 
						
							| 40 | 39 | zcnd |  |-  ( k e. ( ( M + K ) ... ( N + K ) ) -> k e. CC ) | 
						
							| 41 |  | df-neg |  |-  -u ( K - k ) = ( 0 - ( K - k ) ) | 
						
							| 42 |  | negsubdi2 |  |-  ( ( K e. CC /\ k e. CC ) -> -u ( K - k ) = ( k - K ) ) | 
						
							| 43 | 41 42 | eqtr3id |  |-  ( ( K e. CC /\ k e. CC ) -> ( 0 - ( K - k ) ) = ( k - K ) ) | 
						
							| 44 | 20 40 43 | syl2an |  |-  ( ( K e. ZZ /\ k e. ( ( M + K ) ... ( N + K ) ) ) -> ( 0 - ( K - k ) ) = ( k - K ) ) | 
						
							| 45 | 44 | sbceq1d |  |-  ( ( K e. ZZ /\ k e. ( ( M + K ) ... ( N + K ) ) ) -> ( [. ( 0 - ( K - k ) ) / j ]. ph <-> [. ( k - K ) / j ]. ph ) ) | 
						
							| 46 | 45 | ralbidva |  |-  ( K e. ZZ -> ( A. k e. ( ( M + K ) ... ( N + K ) ) [. ( 0 - ( K - k ) ) / j ]. ph <-> A. k e. ( ( M + K ) ... ( N + K ) ) [. ( k - K ) / j ]. ph ) ) | 
						
							| 47 | 46 | 3ad2ant3 |  |-  ( ( M e. ZZ /\ N e. ZZ /\ K e. ZZ ) -> ( A. k e. ( ( M + K ) ... ( N + K ) ) [. ( 0 - ( K - k ) ) / j ]. ph <-> A. k e. ( ( M + K ) ... ( N + K ) ) [. ( k - K ) / j ]. ph ) ) | 
						
							| 48 | 38 47 | bitrd |  |-  ( ( M e. ZZ /\ N e. ZZ /\ K e. ZZ ) -> ( A. k e. ( ( K - ( 0 - M ) ) ... ( K - ( 0 - N ) ) ) [. ( 0 - ( K - k ) ) / j ]. ph <-> A. k e. ( ( M + K ) ... ( N + K ) ) [. ( k - K ) / j ]. ph ) ) | 
						
							| 49 | 17 48 | bitrid |  |-  ( ( M e. ZZ /\ N e. ZZ /\ K e. ZZ ) -> ( A. k e. ( ( K - ( 0 - M ) ) ... ( K - ( 0 - N ) ) ) [. ( K - k ) / x ]. [. ( 0 - x ) / j ]. ph <-> A. k e. ( ( M + K ) ... ( N + K ) ) [. ( k - K ) / j ]. ph ) ) | 
						
							| 50 | 4 12 49 | 3bitrd |  |-  ( ( M e. ZZ /\ N e. ZZ /\ K e. ZZ ) -> ( A. j e. ( M ... N ) ph <-> A. k e. ( ( M + K ) ... ( N + K ) ) [. ( k - K ) / j ]. ph ) ) |