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Mirrors > Home > ILE Home > Th. List > permnn | GIF version |
Description: The number of permutations of 𝑁 − 𝑅 objects from a collection of 𝑁 objects is a positive integer. (Contributed by Jason Orendorff, 24-Jan-2007.) |
Ref | Expression |
---|---|
permnn | ⊢ (𝑅 ∈ (0...𝑁) → ((!‘𝑁) / (!‘𝑅)) ∈ ℕ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | elfznn0 10087 | . . 3 ⊢ (𝑅 ∈ (0...𝑁) → 𝑅 ∈ ℕ0) | |
2 | 1 | faccld 10687 | . 2 ⊢ (𝑅 ∈ (0...𝑁) → (!‘𝑅) ∈ ℕ) |
3 | fznn0sub 10030 | . . . 4 ⊢ (𝑅 ∈ (0...𝑁) → (𝑁 − 𝑅) ∈ ℕ0) | |
4 | 3 | faccld 10687 | . . 3 ⊢ (𝑅 ∈ (0...𝑁) → (!‘(𝑁 − 𝑅)) ∈ ℕ) |
5 | 4, 2 | nnmulcld 8944 | . 2 ⊢ (𝑅 ∈ (0...𝑁) → ((!‘(𝑁 − 𝑅)) · (!‘𝑅)) ∈ ℕ) |
6 | elfz3nn0 10088 | . . 3 ⊢ (𝑅 ∈ (0...𝑁) → 𝑁 ∈ ℕ0) | |
7 | faccl 10686 | . . . 4 ⊢ (𝑁 ∈ ℕ0 → (!‘𝑁) ∈ ℕ) | |
8 | 7 | nncnd 8909 | . . 3 ⊢ (𝑁 ∈ ℕ0 → (!‘𝑁) ∈ ℂ) |
9 | 6, 8 | syl 14 | . 2 ⊢ (𝑅 ∈ (0...𝑁) → (!‘𝑁) ∈ ℂ) |
10 | 4 | nncnd 8909 | . . . 4 ⊢ (𝑅 ∈ (0...𝑁) → (!‘(𝑁 − 𝑅)) ∈ ℂ) |
11 | 2 | nncnd 8909 | . . . 4 ⊢ (𝑅 ∈ (0...𝑁) → (!‘𝑅) ∈ ℂ) |
12 | 2 | nnap0d 8941 | . . . 4 ⊢ (𝑅 ∈ (0...𝑁) → (!‘𝑅) # 0) |
13 | 10, 11, 12 | divcanap4d 8729 | . . 3 ⊢ (𝑅 ∈ (0...𝑁) → (((!‘(𝑁 − 𝑅)) · (!‘𝑅)) / (!‘𝑅)) = (!‘(𝑁 − 𝑅))) |
14 | 13, 4 | eqeltrd 2254 | . 2 ⊢ (𝑅 ∈ (0...𝑁) → (((!‘(𝑁 − 𝑅)) · (!‘𝑅)) / (!‘𝑅)) ∈ ℕ) |
15 | bcval2 10701 | . . 3 ⊢ (𝑅 ∈ (0...𝑁) → (𝑁C𝑅) = ((!‘𝑁) / ((!‘(𝑁 − 𝑅)) · (!‘𝑅)))) | |
16 | bccl2 10719 | . . 3 ⊢ (𝑅 ∈ (0...𝑁) → (𝑁C𝑅) ∈ ℕ) | |
17 | 15, 16 | eqeltrrd 2255 | . 2 ⊢ (𝑅 ∈ (0...𝑁) → ((!‘𝑁) / ((!‘(𝑁 − 𝑅)) · (!‘𝑅))) ∈ ℕ) |
18 | nndivtr 8937 | . 2 ⊢ ((((!‘𝑅) ∈ ℕ ∧ ((!‘(𝑁 − 𝑅)) · (!‘𝑅)) ∈ ℕ ∧ (!‘𝑁) ∈ ℂ) ∧ ((((!‘(𝑁 − 𝑅)) · (!‘𝑅)) / (!‘𝑅)) ∈ ℕ ∧ ((!‘𝑁) / ((!‘(𝑁 − 𝑅)) · (!‘𝑅))) ∈ ℕ)) → ((!‘𝑁) / (!‘𝑅)) ∈ ℕ) | |
19 | 2, 5, 9, 14, 17, 18 | syl32anc 1246 | 1 ⊢ (𝑅 ∈ (0...𝑁) → ((!‘𝑁) / (!‘𝑅)) ∈ ℕ) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∈ wcel 2148 ‘cfv 5211 (class class class)co 5868 ℂcc 7787 0cc0 7789 · cmul 7794 − cmin 8105 / cdiv 8605 ℕcn 8895 ℕ0cn0 9152 ...cfz 9982 !cfa 10676 Ccbc 10698 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-in1 614 ax-in2 615 ax-io 709 ax-5 1447 ax-7 1448 ax-gen 1449 ax-ie1 1493 ax-ie2 1494 ax-8 1504 ax-10 1505 ax-11 1506 ax-i12 1507 ax-bndl 1509 ax-4 1510 ax-17 1526 ax-i9 1530 ax-ial 1534 ax-i5r 1535 ax-13 2150 ax-14 2151 ax-ext 2159 ax-coll 4115 ax-sep 4118 ax-nul 4126 ax-pow 4171 ax-pr 4205 ax-un 4429 ax-setind 4532 ax-iinf 4583 ax-cnex 7880 ax-resscn 7881 ax-1cn 7882 ax-1re 7883 ax-icn 7884 ax-addcl 7885 ax-addrcl 7886 ax-mulcl 7887 ax-mulrcl 7888 ax-addcom 7889 ax-mulcom 7890 ax-addass 7891 ax-mulass 7892 ax-distr 7893 ax-i2m1 7894 ax-0lt1 7895 ax-1rid 7896 ax-0id 7897 ax-rnegex 7898 ax-precex 7899 ax-cnre 7900 ax-pre-ltirr 7901 ax-pre-ltwlin 7902 ax-pre-lttrn 7903 ax-pre-apti 7904 ax-pre-ltadd 7905 ax-pre-mulgt0 7906 ax-pre-mulext 7907 |
This theorem depends on definitions: df-bi 117 df-dc 835 df-3or 979 df-3an 980 df-tru 1356 df-fal 1359 df-nf 1461 df-sb 1763 df-eu 2029 df-mo 2030 df-clab 2164 df-cleq 2170 df-clel 2173 df-nfc 2308 df-ne 2348 df-nel 2443 df-ral 2460 df-rex 2461 df-reu 2462 df-rmo 2463 df-rab 2464 df-v 2739 df-sbc 2963 df-csb 3058 df-dif 3131 df-un 3133 df-in 3135 df-ss 3142 df-nul 3423 df-if 3535 df-pw 3576 df-sn 3597 df-pr 3598 df-op 3600 df-uni 3808 df-int 3843 df-iun 3886 df-br 4001 df-opab 4062 df-mpt 4063 df-tr 4099 df-id 4289 df-po 4292 df-iso 4293 df-iord 4362 df-on 4364 df-ilim 4365 df-suc 4367 df-iom 4586 df-xp 4628 df-rel 4629 df-cnv 4630 df-co 4631 df-dm 4632 df-rn 4633 df-res 4634 df-ima 4635 df-iota 5173 df-fun 5213 df-fn 5214 df-f 5215 df-f1 5216 df-fo 5217 df-f1o 5218 df-fv 5219 df-riota 5824 df-ov 5871 df-oprab 5872 df-mpo 5873 df-1st 6134 df-2nd 6135 df-recs 6299 df-frec 6385 df-pnf 7971 df-mnf 7972 df-xr 7973 df-ltxr 7974 df-le 7975 df-sub 8107 df-neg 8108 df-reap 8509 df-ap 8516 df-div 8606 df-inn 8896 df-n0 9153 df-z 9230 df-uz 9505 df-q 9596 df-rp 9628 df-fz 9983 df-seqfrec 10419 df-fac 10677 df-bc 10699 |
This theorem is referenced by: eirraplem 11755 |
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