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Mirrors > Home > ILE Home > Th. List > hashdifpr | GIF version |
Description: The size of the difference of a finite set and a proper ordered pair subset is the set's size minus 2. (Contributed by AV, 16-Dec-2020.) |
Ref | Expression |
---|---|
hashdifpr | ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → (♯‘(𝐴 ∖ {𝐵, 𝐶})) = ((♯‘𝐴) − 2)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | difpr 3746 | . . . 4 ⊢ (𝐴 ∖ {𝐵, 𝐶}) = ((𝐴 ∖ {𝐵}) ∖ {𝐶}) | |
2 | 1 | a1i 9 | . . 3 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → (𝐴 ∖ {𝐵, 𝐶}) = ((𝐴 ∖ {𝐵}) ∖ {𝐶})) |
3 | 2 | fveq2d 5531 | . 2 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → (♯‘(𝐴 ∖ {𝐵, 𝐶})) = (♯‘((𝐴 ∖ {𝐵}) ∖ {𝐶}))) |
4 | simpl 109 | . . . 4 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → 𝐴 ∈ Fin) | |
5 | snfig 6827 | . . . . . 6 ⊢ (𝐵 ∈ 𝐴 → {𝐵} ∈ Fin) | |
6 | 5 | 3ad2ant1 1019 | . . . . 5 ⊢ ((𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶) → {𝐵} ∈ Fin) |
7 | 6 | adantl 277 | . . . 4 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → {𝐵} ∈ Fin) |
8 | snssi 3748 | . . . . . 6 ⊢ (𝐵 ∈ 𝐴 → {𝐵} ⊆ 𝐴) | |
9 | 8 | 3ad2ant1 1019 | . . . . 5 ⊢ ((𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶) → {𝐵} ⊆ 𝐴) |
10 | 9 | adantl 277 | . . . 4 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → {𝐵} ⊆ 𝐴) |
11 | diffifi 6907 | . . . 4 ⊢ ((𝐴 ∈ Fin ∧ {𝐵} ∈ Fin ∧ {𝐵} ⊆ 𝐴) → (𝐴 ∖ {𝐵}) ∈ Fin) | |
12 | 4, 7, 10, 11 | syl3anc 1248 | . . 3 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → (𝐴 ∖ {𝐵}) ∈ Fin) |
13 | simpr2 1005 | . . . 4 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → 𝐶 ∈ 𝐴) | |
14 | simpr3 1006 | . . . . 5 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → 𝐵 ≠ 𝐶) | |
15 | 14 | necomd 2443 | . . . 4 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → 𝐶 ≠ 𝐵) |
16 | eldifsn 3731 | . . . 4 ⊢ (𝐶 ∈ (𝐴 ∖ {𝐵}) ↔ (𝐶 ∈ 𝐴 ∧ 𝐶 ≠ 𝐵)) | |
17 | 13, 15, 16 | sylanbrc 417 | . . 3 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → 𝐶 ∈ (𝐴 ∖ {𝐵})) |
18 | hashdifsn 10812 | . . 3 ⊢ (((𝐴 ∖ {𝐵}) ∈ Fin ∧ 𝐶 ∈ (𝐴 ∖ {𝐵})) → (♯‘((𝐴 ∖ {𝐵}) ∖ {𝐶})) = ((♯‘(𝐴 ∖ {𝐵})) − 1)) | |
19 | 12, 17, 18 | syl2anc 411 | . 2 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → (♯‘((𝐴 ∖ {𝐵}) ∖ {𝐶})) = ((♯‘(𝐴 ∖ {𝐵})) − 1)) |
20 | hashdifsn 10812 | . . . . 5 ⊢ ((𝐴 ∈ Fin ∧ 𝐵 ∈ 𝐴) → (♯‘(𝐴 ∖ {𝐵})) = ((♯‘𝐴) − 1)) | |
21 | 20 | 3ad2antr1 1163 | . . . 4 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → (♯‘(𝐴 ∖ {𝐵})) = ((♯‘𝐴) − 1)) |
22 | 21 | oveq1d 5903 | . . 3 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → ((♯‘(𝐴 ∖ {𝐵})) − 1) = (((♯‘𝐴) − 1) − 1)) |
23 | hashcl 10774 | . . . . . 6 ⊢ (𝐴 ∈ Fin → (♯‘𝐴) ∈ ℕ0) | |
24 | 23 | nn0cnd 9244 | . . . . 5 ⊢ (𝐴 ∈ Fin → (♯‘𝐴) ∈ ℂ) |
25 | sub1m1 9182 | . . . . 5 ⊢ ((♯‘𝐴) ∈ ℂ → (((♯‘𝐴) − 1) − 1) = ((♯‘𝐴) − 2)) | |
26 | 24, 25 | syl 14 | . . . 4 ⊢ (𝐴 ∈ Fin → (((♯‘𝐴) − 1) − 1) = ((♯‘𝐴) − 2)) |
27 | 26 | adantr 276 | . . 3 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → (((♯‘𝐴) − 1) − 1) = ((♯‘𝐴) − 2)) |
28 | 22, 27 | eqtrd 2220 | . 2 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → ((♯‘(𝐴 ∖ {𝐵})) − 1) = ((♯‘𝐴) − 2)) |
29 | 3, 19, 28 | 3eqtrd 2224 | 1 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → (♯‘(𝐴 ∖ {𝐵, 𝐶})) = ((♯‘𝐴) − 2)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 104 ∧ w3a 979 = wceq 1363 ∈ wcel 2158 ≠ wne 2357 ∖ cdif 3138 ⊆ wss 3141 {csn 3604 {cpr 3605 ‘cfv 5228 (class class class)co 5888 Fincfn 6753 ℂcc 7822 1c1 7825 − cmin 8141 2c2 8983 ♯chash 10768 |
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 615 ax-in2 616 ax-io 710 ax-5 1457 ax-7 1458 ax-gen 1459 ax-ie1 1503 ax-ie2 1504 ax-8 1514 ax-10 1515 ax-11 1516 ax-i12 1517 ax-bndl 1519 ax-4 1520 ax-17 1536 ax-i9 1540 ax-ial 1544 ax-i5r 1545 ax-13 2160 ax-14 2161 ax-ext 2169 ax-coll 4130 ax-sep 4133 ax-nul 4141 ax-pow 4186 ax-pr 4221 ax-un 4445 ax-setind 4548 ax-iinf 4599 ax-cnex 7915 ax-resscn 7916 ax-1cn 7917 ax-1re 7918 ax-icn 7919 ax-addcl 7920 ax-addrcl 7921 ax-mulcl 7922 ax-addcom 7924 ax-addass 7926 ax-distr 7928 ax-i2m1 7929 ax-0lt1 7930 ax-0id 7932 ax-rnegex 7933 ax-cnre 7935 ax-pre-ltirr 7936 ax-pre-ltwlin 7937 ax-pre-lttrn 7938 ax-pre-apti 7939 ax-pre-ltadd 7940 |
This theorem depends on definitions: df-bi 117 df-dc 836 df-3or 980 df-3an 981 df-tru 1366 df-fal 1369 df-nf 1471 df-sb 1773 df-eu 2039 df-mo 2040 df-clab 2174 df-cleq 2180 df-clel 2183 df-nfc 2318 df-ne 2358 df-nel 2453 df-ral 2470 df-rex 2471 df-reu 2472 df-rab 2474 df-v 2751 df-sbc 2975 df-csb 3070 df-dif 3143 df-un 3145 df-in 3147 df-ss 3154 df-nul 3435 df-if 3547 df-pw 3589 df-sn 3610 df-pr 3611 df-op 3613 df-uni 3822 df-int 3857 df-iun 3900 df-br 4016 df-opab 4077 df-mpt 4078 df-tr 4114 df-id 4305 df-iord 4378 df-on 4380 df-ilim 4381 df-suc 4383 df-iom 4602 df-xp 4644 df-rel 4645 df-cnv 4646 df-co 4647 df-dm 4648 df-rn 4649 df-res 4650 df-ima 4651 df-iota 5190 df-fun 5230 df-fn 5231 df-f 5232 df-f1 5233 df-fo 5234 df-f1o 5235 df-fv 5236 df-riota 5844 df-ov 5891 df-oprab 5892 df-mpo 5893 df-1st 6154 df-2nd 6155 df-recs 6319 df-irdg 6384 df-frec 6405 df-1o 6430 df-oadd 6434 df-er 6548 df-en 6754 df-dom 6755 df-fin 6756 df-pnf 8007 df-mnf 8008 df-xr 8009 df-ltxr 8010 df-le 8011 df-sub 8143 df-neg 8144 df-inn 8933 df-2 8991 df-n0 9190 df-z 9267 df-uz 9542 df-fz 10022 df-ihash 10769 |
This theorem is referenced by: (None) |
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