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Description: The quotient of two finite products. (Contributed by Scott Fenton, 15-Jan-2018)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | fprodmul.1 | |- ( ph -> A e. Fin ) |
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| fprodmul.2 | |- ( ( ph /\ k e. A ) -> B e. CC ) |
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| fprodmul.3 | |- ( ( ph /\ k e. A ) -> C e. CC ) |
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| fproddiv.4 | |- ( ( ph /\ k e. A ) -> C =/= 0 ) |
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| Assertion | fproddiv | |- ( ph -> prod_ k e. A ( B / C ) = ( prod_ k e. A B / prod_ k e. A C ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | fprodmul.1 | |- ( ph -> A e. Fin ) |
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| 2 | fprodmul.2 | |- ( ( ph /\ k e. A ) -> B e. CC ) |
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| 3 | fprodmul.3 | |- ( ( ph /\ k e. A ) -> C e. CC ) |
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| 4 | fproddiv.4 | |- ( ( ph /\ k e. A ) -> C =/= 0 ) |
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| 5 | 1div1e1 | |- ( 1 / 1 ) = 1 |
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| 6 | 5 | eqcomi | |- 1 = ( 1 / 1 ) |
| 7 | prodeq1 | |- ( A = (/) -> prod_ k e. A ( B / C ) = prod_ k e. (/) ( B / C ) ) |
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| 8 | prod0 | |- prod_ k e. (/) ( B / C ) = 1 |
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| 9 | 7 8 | eqtrdi | |- ( A = (/) -> prod_ k e. A ( B / C ) = 1 ) |
| 10 | prodeq1 | |- ( A = (/) -> prod_ k e. A B = prod_ k e. (/) B ) |
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| 11 | prod0 | |- prod_ k e. (/) B = 1 |
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| 12 | 10 11 | eqtrdi | |- ( A = (/) -> prod_ k e. A B = 1 ) |
| 13 | prodeq1 | |- ( A = (/) -> prod_ k e. A C = prod_ k e. (/) C ) |
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| 14 | prod0 | |- prod_ k e. (/) C = 1 |
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| 15 | 13 14 | eqtrdi | |- ( A = (/) -> prod_ k e. A C = 1 ) |
| 16 | 12 15 | oveq12d | |- ( A = (/) -> ( prod_ k e. A B / prod_ k e. A C ) = ( 1 / 1 ) ) |
| 17 | 6 9 16 | 3eqtr4a | |- ( A = (/) -> prod_ k e. A ( B / C ) = ( prod_ k e. A B / prod_ k e. A C ) ) |
| 18 | 17 | a1i | |- ( ph -> ( A = (/) -> prod_ k e. A ( B / C ) = ( prod_ k e. A B / prod_ k e. A C ) ) ) |
| 19 | simprl | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> ( # ` A ) e. NN ) |
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| 20 | nnuz | |- NN = ( ZZ>= ` 1 ) |
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| 21 | 19 20 | eleqtrdi | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> ( # ` A ) e. ( ZZ>= ` 1 ) ) |
| 22 | 2 | fmpttd | |- ( ph -> ( k e. A |-> B ) : A --> CC ) |
| 23 | f1of | |- ( f : ( 1 ... ( # ` A ) ) -1-1-onto-> A -> f : ( 1 ... ( # ` A ) ) --> A ) |
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| 24 | 23 | adantl | |- ( ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) -> f : ( 1 ... ( # ` A ) ) --> A ) |
| 25 | fco | |- ( ( ( k e. A |-> B ) : A --> CC /\ f : ( 1 ... ( # ` A ) ) --> A ) -> ( ( k e. A |-> B ) o. f ) : ( 1 ... ( # ` A ) ) --> CC ) |
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| 26 | 22 24 25 | syl2an | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> ( ( k e. A |-> B ) o. f ) : ( 1 ... ( # ` A ) ) --> CC ) |
| 27 | 26 | ffvelcdmda | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( ( k e. A |-> B ) o. f ) ` n ) e. CC ) |
| 28 | 3 | fmpttd | |- ( ph -> ( k e. A |-> C ) : A --> CC ) |
| 29 | fco | |- ( ( ( k e. A |-> C ) : A --> CC /\ f : ( 1 ... ( # ` A ) ) --> A ) -> ( ( k e. A |-> C ) o. f ) : ( 1 ... ( # ` A ) ) --> CC ) |
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| 30 | 28 24 29 | syl2an | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> ( ( k e. A |-> C ) o. f ) : ( 1 ... ( # ` A ) ) --> CC ) |
| 31 | 30 | ffvelcdmda | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( ( k e. A |-> C ) o. f ) ` n ) e. CC ) |
| 32 | simprr | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) |
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| 33 | 32 23 | syl | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> f : ( 1 ... ( # ` A ) ) --> A ) |
| 34 | fvco3 | |- ( ( f : ( 1 ... ( # ` A ) ) --> A /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( ( k e. A |-> C ) o. f ) ` n ) = ( ( k e. A |-> C ) ` ( f ` n ) ) ) |
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| 35 | 33 34 | sylan | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( ( k e. A |-> C ) o. f ) ` n ) = ( ( k e. A |-> C ) ` ( f ` n ) ) ) |
| 36 | 33 | ffvelcdmda | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> ( f ` n ) e. A ) |
| 37 | simpr | |- ( ( ph /\ k e. A ) -> k e. A ) |
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| 38 | eqid | |- ( k e. A |-> C ) = ( k e. A |-> C ) |
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| 39 | 38 | fvmpt2 | |- ( ( k e. A /\ C e. CC ) -> ( ( k e. A |-> C ) ` k ) = C ) |
| 40 | 37 3 39 | syl2anc | |- ( ( ph /\ k e. A ) -> ( ( k e. A |-> C ) ` k ) = C ) |
| 41 | 40 4 | eqnetrd | |- ( ( ph /\ k e. A ) -> ( ( k e. A |-> C ) ` k ) =/= 0 ) |
| 42 | 41 | ralrimiva | |- ( ph -> A. k e. A ( ( k e. A |-> C ) ` k ) =/= 0 ) |
| 43 | 42 | ad2antrr | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> A. k e. A ( ( k e. A |-> C ) ` k ) =/= 0 ) |
| 44 | nffvmpt1 | |- F/_ k ( ( k e. A |-> C ) ` ( f ` n ) ) |
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| 45 | nfcv | |- F/_ k 0 |
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| 46 | 44 45 | nfne | |- F/ k ( ( k e. A |-> C ) ` ( f ` n ) ) =/= 0 |
| 47 | fveq2 | |- ( k = ( f ` n ) -> ( ( k e. A |-> C ) ` k ) = ( ( k e. A |-> C ) ` ( f ` n ) ) ) |
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| 48 | 47 | neeq1d | |- ( k = ( f ` n ) -> ( ( ( k e. A |-> C ) ` k ) =/= 0 <-> ( ( k e. A |-> C ) ` ( f ` n ) ) =/= 0 ) ) |
| 49 | 46 48 | rspc | |- ( ( f ` n ) e. A -> ( A. k e. A ( ( k e. A |-> C ) ` k ) =/= 0 -> ( ( k e. A |-> C ) ` ( f ` n ) ) =/= 0 ) ) |
| 50 | 36 43 49 | sylc | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( k e. A |-> C ) ` ( f ` n ) ) =/= 0 ) |
| 51 | 35 50 | eqnetrd | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( ( k e. A |-> C ) o. f ) ` n ) =/= 0 ) |
| 52 | 2 3 4 | divcld | |- ( ( ph /\ k e. A ) -> ( B / C ) e. CC ) |
| 53 | eqid | |- ( k e. A |-> ( B / C ) ) = ( k e. A |-> ( B / C ) ) |
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| 54 | 53 | fvmpt2 | |- ( ( k e. A /\ ( B / C ) e. CC ) -> ( ( k e. A |-> ( B / C ) ) ` k ) = ( B / C ) ) |
| 55 | 37 52 54 | syl2anc | |- ( ( ph /\ k e. A ) -> ( ( k e. A |-> ( B / C ) ) ` k ) = ( B / C ) ) |
| 56 | eqid | |- ( k e. A |-> B ) = ( k e. A |-> B ) |
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| 57 | 56 | fvmpt2 | |- ( ( k e. A /\ B e. CC ) -> ( ( k e. A |-> B ) ` k ) = B ) |
| 58 | 37 2 57 | syl2anc | |- ( ( ph /\ k e. A ) -> ( ( k e. A |-> B ) ` k ) = B ) |
| 59 | 58 40 | oveq12d | |- ( ( ph /\ k e. A ) -> ( ( ( k e. A |-> B ) ` k ) / ( ( k e. A |-> C ) ` k ) ) = ( B / C ) ) |
| 60 | 55 59 | eqtr4d | |- ( ( ph /\ k e. A ) -> ( ( k e. A |-> ( B / C ) ) ` k ) = ( ( ( k e. A |-> B ) ` k ) / ( ( k e. A |-> C ) ` k ) ) ) |
| 61 | 60 | ralrimiva | |- ( ph -> A. k e. A ( ( k e. A |-> ( B / C ) ) ` k ) = ( ( ( k e. A |-> B ) ` k ) / ( ( k e. A |-> C ) ` k ) ) ) |
| 62 | 61 | ad2antrr | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> A. k e. A ( ( k e. A |-> ( B / C ) ) ` k ) = ( ( ( k e. A |-> B ) ` k ) / ( ( k e. A |-> C ) ` k ) ) ) |
| 63 | nffvmpt1 | |- F/_ k ( ( k e. A |-> ( B / C ) ) ` ( f ` n ) ) |
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| 64 | nffvmpt1 | |- F/_ k ( ( k e. A |-> B ) ` ( f ` n ) ) |
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| 65 | nfcv | |- F/_ k / |
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| 66 | 64 65 44 | nfov | |- F/_ k ( ( ( k e. A |-> B ) ` ( f ` n ) ) / ( ( k e. A |-> C ) ` ( f ` n ) ) ) |
| 67 | 63 66 | nfeq | |- F/ k ( ( k e. A |-> ( B / C ) ) ` ( f ` n ) ) = ( ( ( k e. A |-> B ) ` ( f ` n ) ) / ( ( k e. A |-> C ) ` ( f ` n ) ) ) |
| 68 | fveq2 | |- ( k = ( f ` n ) -> ( ( k e. A |-> ( B / C ) ) ` k ) = ( ( k e. A |-> ( B / C ) ) ` ( f ` n ) ) ) |
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| 69 | fveq2 | |- ( k = ( f ` n ) -> ( ( k e. A |-> B ) ` k ) = ( ( k e. A |-> B ) ` ( f ` n ) ) ) |
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| 70 | 69 47 | oveq12d | |- ( k = ( f ` n ) -> ( ( ( k e. A |-> B ) ` k ) / ( ( k e. A |-> C ) ` k ) ) = ( ( ( k e. A |-> B ) ` ( f ` n ) ) / ( ( k e. A |-> C ) ` ( f ` n ) ) ) ) |
| 71 | 68 70 | eqeq12d | |- ( k = ( f ` n ) -> ( ( ( k e. A |-> ( B / C ) ) ` k ) = ( ( ( k e. A |-> B ) ` k ) / ( ( k e. A |-> C ) ` k ) ) <-> ( ( k e. A |-> ( B / C ) ) ` ( f ` n ) ) = ( ( ( k e. A |-> B ) ` ( f ` n ) ) / ( ( k e. A |-> C ) ` ( f ` n ) ) ) ) ) |
| 72 | 67 71 | rspc | |- ( ( f ` n ) e. A -> ( A. k e. A ( ( k e. A |-> ( B / C ) ) ` k ) = ( ( ( k e. A |-> B ) ` k ) / ( ( k e. A |-> C ) ` k ) ) -> ( ( k e. A |-> ( B / C ) ) ` ( f ` n ) ) = ( ( ( k e. A |-> B ) ` ( f ` n ) ) / ( ( k e. A |-> C ) ` ( f ` n ) ) ) ) ) |
| 73 | 36 62 72 | sylc | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( k e. A |-> ( B / C ) ) ` ( f ` n ) ) = ( ( ( k e. A |-> B ) ` ( f ` n ) ) / ( ( k e. A |-> C ) ` ( f ` n ) ) ) ) |
| 74 | fvco3 | |- ( ( f : ( 1 ... ( # ` A ) ) --> A /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( ( k e. A |-> ( B / C ) ) o. f ) ` n ) = ( ( k e. A |-> ( B / C ) ) ` ( f ` n ) ) ) |
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| 75 | 33 74 | sylan | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( ( k e. A |-> ( B / C ) ) o. f ) ` n ) = ( ( k e. A |-> ( B / C ) ) ` ( f ` n ) ) ) |
| 76 | fvco3 | |- ( ( f : ( 1 ... ( # ` A ) ) --> A /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( ( k e. A |-> B ) o. f ) ` n ) = ( ( k e. A |-> B ) ` ( f ` n ) ) ) |
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| 77 | 33 76 | sylan | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( ( k e. A |-> B ) o. f ) ` n ) = ( ( k e. A |-> B ) ` ( f ` n ) ) ) |
| 78 | 77 35 | oveq12d | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( ( ( k e. A |-> B ) o. f ) ` n ) / ( ( ( k e. A |-> C ) o. f ) ` n ) ) = ( ( ( k e. A |-> B ) ` ( f ` n ) ) / ( ( k e. A |-> C ) ` ( f ` n ) ) ) ) |
| 79 | 73 75 78 | 3eqtr4d | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ n e. ( 1 ... ( # ` A ) ) ) -> ( ( ( k e. A |-> ( B / C ) ) o. f ) ` n ) = ( ( ( ( k e. A |-> B ) o. f ) ` n ) / ( ( ( k e. A |-> C ) o. f ) ` n ) ) ) |
| 80 | 21 27 31 51 79 | prodfdiv | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> ( seq 1 ( x. , ( ( k e. A |-> ( B / C ) ) o. f ) ) ` ( # ` A ) ) = ( ( seq 1 ( x. , ( ( k e. A |-> B ) o. f ) ) ` ( # ` A ) ) / ( seq 1 ( x. , ( ( k e. A |-> C ) o. f ) ) ` ( # ` A ) ) ) ) |
| 81 | fveq2 | |- ( m = ( f ` n ) -> ( ( k e. A |-> ( B / C ) ) ` m ) = ( ( k e. A |-> ( B / C ) ) ` ( f ` n ) ) ) |
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| 82 | 52 | fmpttd | |- ( ph -> ( k e. A |-> ( B / C ) ) : A --> CC ) |
| 83 | 82 | adantr | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> ( k e. A |-> ( B / C ) ) : A --> CC ) |
| 84 | 83 | ffvelcdmda | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ m e. A ) -> ( ( k e. A |-> ( B / C ) ) ` m ) e. CC ) |
| 85 | 81 19 32 84 75 | fprod | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> prod_ m e. A ( ( k e. A |-> ( B / C ) ) ` m ) = ( seq 1 ( x. , ( ( k e. A |-> ( B / C ) ) o. f ) ) ` ( # ` A ) ) ) |
| 86 | fveq2 | |- ( m = ( f ` n ) -> ( ( k e. A |-> B ) ` m ) = ( ( k e. A |-> B ) ` ( f ` n ) ) ) |
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| 87 | 22 | adantr | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> ( k e. A |-> B ) : A --> CC ) |
| 88 | 87 | ffvelcdmda | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ m e. A ) -> ( ( k e. A |-> B ) ` m ) e. CC ) |
| 89 | 86 19 32 88 77 | fprod | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> prod_ m e. A ( ( k e. A |-> B ) ` m ) = ( seq 1 ( x. , ( ( k e. A |-> B ) o. f ) ) ` ( # ` A ) ) ) |
| 90 | fveq2 | |- ( m = ( f ` n ) -> ( ( k e. A |-> C ) ` m ) = ( ( k e. A |-> C ) ` ( f ` n ) ) ) |
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| 91 | 28 | adantr | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> ( k e. A |-> C ) : A --> CC ) |
| 92 | 91 | ffvelcdmda | |- ( ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) /\ m e. A ) -> ( ( k e. A |-> C ) ` m ) e. CC ) |
| 93 | 90 19 32 92 35 | fprod | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> prod_ m e. A ( ( k e. A |-> C ) ` m ) = ( seq 1 ( x. , ( ( k e. A |-> C ) o. f ) ) ` ( # ` A ) ) ) |
| 94 | 89 93 | oveq12d | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> ( prod_ m e. A ( ( k e. A |-> B ) ` m ) / prod_ m e. A ( ( k e. A |-> C ) ` m ) ) = ( ( seq 1 ( x. , ( ( k e. A |-> B ) o. f ) ) ` ( # ` A ) ) / ( seq 1 ( x. , ( ( k e. A |-> C ) o. f ) ) ` ( # ` A ) ) ) ) |
| 95 | 80 85 94 | 3eqtr4d | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> prod_ m e. A ( ( k e. A |-> ( B / C ) ) ` m ) = ( prod_ m e. A ( ( k e. A |-> B ) ` m ) / prod_ m e. A ( ( k e. A |-> C ) ` m ) ) ) |
| 96 | prodfc | |- prod_ m e. A ( ( k e. A |-> ( B / C ) ) ` m ) = prod_ k e. A ( B / C ) |
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| 97 | prodfc | |- prod_ m e. A ( ( k e. A |-> B ) ` m ) = prod_ k e. A B |
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| 98 | prodfc | |- prod_ m e. A ( ( k e. A |-> C ) ` m ) = prod_ k e. A C |
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| 99 | 97 98 | oveq12i | |- ( prod_ m e. A ( ( k e. A |-> B ) ` m ) / prod_ m e. A ( ( k e. A |-> C ) ` m ) ) = ( prod_ k e. A B / prod_ k e. A C ) |
| 100 | 95 96 99 | 3eqtr3g | |- ( ( ph /\ ( ( # ` A ) e. NN /\ f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) -> prod_ k e. A ( B / C ) = ( prod_ k e. A B / prod_ k e. A C ) ) |
| 101 | 100 | expr | |- ( ( ph /\ ( # ` A ) e. NN ) -> ( f : ( 1 ... ( # ` A ) ) -1-1-onto-> A -> prod_ k e. A ( B / C ) = ( prod_ k e. A B / prod_ k e. A C ) ) ) |
| 102 | 101 | exlimdv | |- ( ( ph /\ ( # ` A ) e. NN ) -> ( E. f f : ( 1 ... ( # ` A ) ) -1-1-onto-> A -> prod_ k e. A ( B / C ) = ( prod_ k e. A B / prod_ k e. A C ) ) ) |
| 103 | 102 | expimpd | |- ( ph -> ( ( ( # ` A ) e. NN /\ E. f f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) -> prod_ k e. A ( B / C ) = ( prod_ k e. A B / prod_ k e. A C ) ) ) |
| 104 | fz1f1o | |- ( A e. Fin -> ( A = (/) \/ ( ( # ` A ) e. NN /\ E. f f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) ) |
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| 105 | 1 104 | syl | |- ( ph -> ( A = (/) \/ ( ( # ` A ) e. NN /\ E. f f : ( 1 ... ( # ` A ) ) -1-1-onto-> A ) ) ) |
| 106 | 18 103 105 | mpjaod | |- ( ph -> prod_ k e. A ( B / C ) = ( prod_ k e. A B / prod_ k e. A C ) ) |