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Description: Identity law for modulo. (Contributed by NM, 29-Dec-2008)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | modid | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( A mod B ) = A ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | modval | |- ( ( A e. RR /\ B e. RR+ ) -> ( A mod B ) = ( A - ( B x. ( |_ ` ( A / B ) ) ) ) ) |
|
| 2 | 1 | adantr | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( A mod B ) = ( A - ( B x. ( |_ ` ( A / B ) ) ) ) ) |
| 3 | rerpdivcl | |- ( ( A e. RR /\ B e. RR+ ) -> ( A / B ) e. RR ) |
|
| 4 | 3 | adantr | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( A / B ) e. RR ) |
| 5 | 4 | recnd | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( A / B ) e. CC ) |
| 6 | addlid | |- ( ( A / B ) e. CC -> ( 0 + ( A / B ) ) = ( A / B ) ) |
|
| 7 | 6 | fveq2d | |- ( ( A / B ) e. CC -> ( |_ ` ( 0 + ( A / B ) ) ) = ( |_ ` ( A / B ) ) ) |
| 8 | 5 7 | syl | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( |_ ` ( 0 + ( A / B ) ) ) = ( |_ ` ( A / B ) ) ) |
| 9 | rpregt0 | |- ( B e. RR+ -> ( B e. RR /\ 0 < B ) ) |
|
| 10 | divge0 | |- ( ( ( A e. RR /\ 0 <_ A ) /\ ( B e. RR /\ 0 < B ) ) -> 0 <_ ( A / B ) ) |
|
| 11 | 9 10 | sylan2 | |- ( ( ( A e. RR /\ 0 <_ A ) /\ B e. RR+ ) -> 0 <_ ( A / B ) ) |
| 12 | 11 | an32s | |- ( ( ( A e. RR /\ B e. RR+ ) /\ 0 <_ A ) -> 0 <_ ( A / B ) ) |
| 13 | 12 | adantrr | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> 0 <_ ( A / B ) ) |
| 14 | simpr | |- ( ( B e. RR+ /\ A < B ) -> A < B ) |
|
| 15 | rpcn | |- ( B e. RR+ -> B e. CC ) |
|
| 16 | 15 | mulridd | |- ( B e. RR+ -> ( B x. 1 ) = B ) |
| 17 | 16 | adantr | |- ( ( B e. RR+ /\ A < B ) -> ( B x. 1 ) = B ) |
| 18 | 14 17 | breqtrrd | |- ( ( B e. RR+ /\ A < B ) -> A < ( B x. 1 ) ) |
| 19 | 18 | ad2ant2l | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> A < ( B x. 1 ) ) |
| 20 | simpll | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> A e. RR ) |
|
| 21 | 9 | ad2antlr | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( B e. RR /\ 0 < B ) ) |
| 22 | 1re | |- 1 e. RR |
|
| 23 | ltdivmul | |- ( ( A e. RR /\ 1 e. RR /\ ( B e. RR /\ 0 < B ) ) -> ( ( A / B ) < 1 <-> A < ( B x. 1 ) ) ) |
|
| 24 | 22 23 | mp3an2 | |- ( ( A e. RR /\ ( B e. RR /\ 0 < B ) ) -> ( ( A / B ) < 1 <-> A < ( B x. 1 ) ) ) |
| 25 | 20 21 24 | syl2anc | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( ( A / B ) < 1 <-> A < ( B x. 1 ) ) ) |
| 26 | 19 25 | mpbird | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( A / B ) < 1 ) |
| 27 | 0z | |- 0 e. ZZ |
|
| 28 | flbi2 | |- ( ( 0 e. ZZ /\ ( A / B ) e. RR ) -> ( ( |_ ` ( 0 + ( A / B ) ) ) = 0 <-> ( 0 <_ ( A / B ) /\ ( A / B ) < 1 ) ) ) |
|
| 29 | 27 4 28 | sylancr | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( ( |_ ` ( 0 + ( A / B ) ) ) = 0 <-> ( 0 <_ ( A / B ) /\ ( A / B ) < 1 ) ) ) |
| 30 | 13 26 29 | mpbir2and | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( |_ ` ( 0 + ( A / B ) ) ) = 0 ) |
| 31 | 8 30 | eqtr3d | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( |_ ` ( A / B ) ) = 0 ) |
| 32 | 31 | oveq2d | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( B x. ( |_ ` ( A / B ) ) ) = ( B x. 0 ) ) |
| 33 | 15 | mul01d | |- ( B e. RR+ -> ( B x. 0 ) = 0 ) |
| 34 | 33 | ad2antlr | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( B x. 0 ) = 0 ) |
| 35 | 32 34 | eqtrd | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( B x. ( |_ ` ( A / B ) ) ) = 0 ) |
| 36 | 35 | oveq2d | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( A - ( B x. ( |_ ` ( A / B ) ) ) ) = ( A - 0 ) ) |
| 37 | recn | |- ( A e. RR -> A e. CC ) |
|
| 38 | 37 | subid1d | |- ( A e. RR -> ( A - 0 ) = A ) |
| 39 | 38 | ad2antrr | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( A - 0 ) = A ) |
| 40 | 36 39 | eqtrd | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( A - ( B x. ( |_ ` ( A / B ) ) ) ) = A ) |
| 41 | 2 40 | eqtrd | |- ( ( ( A e. RR /\ B e. RR+ ) /\ ( 0 <_ A /\ A < B ) ) -> ( A mod B ) = A ) |