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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 3761 | . . . 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 5559 | . 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 6870 | . . . . . 6 ⊢ (𝐵 ∈ 𝐴 → {𝐵} ∈ Fin) | |
6 | 5 | 3ad2ant1 1020 | . . . . 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 3763 | . . . . . 6 ⊢ (𝐵 ∈ 𝐴 → {𝐵} ⊆ 𝐴) | |
9 | 8 | 3ad2ant1 1020 | . . . . 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 6952 | . . . 4 ⊢ ((𝐴 ∈ Fin ∧ {𝐵} ∈ Fin ∧ {𝐵} ⊆ 𝐴) → (𝐴 ∖ {𝐵}) ∈ Fin) | |
12 | 4, 7, 10, 11 | syl3anc 1249 | . . 3 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → (𝐴 ∖ {𝐵}) ∈ Fin) |
13 | simpr2 1006 | . . . 4 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → 𝐶 ∈ 𝐴) | |
14 | simpr3 1007 | . . . . 5 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → 𝐵 ≠ 𝐶) | |
15 | 14 | necomd 2450 | . . . 4 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → 𝐶 ≠ 𝐵) |
16 | eldifsn 3746 | . . . 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 10893 | . . 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 10893 | . . . . 5 ⊢ ((𝐴 ∈ Fin ∧ 𝐵 ∈ 𝐴) → (♯‘(𝐴 ∖ {𝐵})) = ((♯‘𝐴) − 1)) | |
21 | 20 | 3ad2antr1 1164 | . . . 4 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → (♯‘(𝐴 ∖ {𝐵})) = ((♯‘𝐴) − 1)) |
22 | 21 | oveq1d 5934 | . . 3 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → ((♯‘(𝐴 ∖ {𝐵})) − 1) = (((♯‘𝐴) − 1) − 1)) |
23 | hashcl 10855 | . . . . . 6 ⊢ (𝐴 ∈ Fin → (♯‘𝐴) ∈ ℕ0) | |
24 | 23 | nn0cnd 9298 | . . . . 5 ⊢ (𝐴 ∈ Fin → (♯‘𝐴) ∈ ℂ) |
25 | sub1m1 9236 | . . . . 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 2226 | . 2 ⊢ ((𝐴 ∈ Fin ∧ (𝐵 ∈ 𝐴 ∧ 𝐶 ∈ 𝐴 ∧ 𝐵 ≠ 𝐶)) → ((♯‘(𝐴 ∖ {𝐵})) − 1) = ((♯‘𝐴) − 2)) |
29 | 3, 19, 28 | 3eqtrd 2230 | 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 980 = wceq 1364 ∈ wcel 2164 ≠ wne 2364 ∖ cdif 3151 ⊆ wss 3154 {csn 3619 {cpr 3620 ‘cfv 5255 (class class class)co 5919 Fincfn 6796 ℂcc 7872 1c1 7875 − cmin 8192 2c2 9035 ♯chash 10849 |
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 1458 ax-7 1459 ax-gen 1460 ax-ie1 1504 ax-ie2 1505 ax-8 1515 ax-10 1516 ax-11 1517 ax-i12 1518 ax-bndl 1520 ax-4 1521 ax-17 1537 ax-i9 1541 ax-ial 1545 ax-i5r 1546 ax-13 2166 ax-14 2167 ax-ext 2175 ax-coll 4145 ax-sep 4148 ax-nul 4156 ax-pow 4204 ax-pr 4239 ax-un 4465 ax-setind 4570 ax-iinf 4621 ax-cnex 7965 ax-resscn 7966 ax-1cn 7967 ax-1re 7968 ax-icn 7969 ax-addcl 7970 ax-addrcl 7971 ax-mulcl 7972 ax-addcom 7974 ax-addass 7976 ax-distr 7978 ax-i2m1 7979 ax-0lt1 7980 ax-0id 7982 ax-rnegex 7983 ax-cnre 7985 ax-pre-ltirr 7986 ax-pre-ltwlin 7987 ax-pre-lttrn 7988 ax-pre-apti 7989 ax-pre-ltadd 7990 |
This theorem depends on definitions: df-bi 117 df-dc 836 df-3or 981 df-3an 982 df-tru 1367 df-fal 1370 df-nf 1472 df-sb 1774 df-eu 2045 df-mo 2046 df-clab 2180 df-cleq 2186 df-clel 2189 df-nfc 2325 df-ne 2365 df-nel 2460 df-ral 2477 df-rex 2478 df-reu 2479 df-rab 2481 df-v 2762 df-sbc 2987 df-csb 3082 df-dif 3156 df-un 3158 df-in 3160 df-ss 3167 df-nul 3448 df-if 3559 df-pw 3604 df-sn 3625 df-pr 3626 df-op 3628 df-uni 3837 df-int 3872 df-iun 3915 df-br 4031 df-opab 4092 df-mpt 4093 df-tr 4129 df-id 4325 df-iord 4398 df-on 4400 df-ilim 4401 df-suc 4403 df-iom 4624 df-xp 4666 df-rel 4667 df-cnv 4668 df-co 4669 df-dm 4670 df-rn 4671 df-res 4672 df-ima 4673 df-iota 5216 df-fun 5257 df-fn 5258 df-f 5259 df-f1 5260 df-fo 5261 df-f1o 5262 df-fv 5263 df-riota 5874 df-ov 5922 df-oprab 5923 df-mpo 5924 df-1st 6195 df-2nd 6196 df-recs 6360 df-irdg 6425 df-frec 6446 df-1o 6471 df-oadd 6475 df-er 6589 df-en 6797 df-dom 6798 df-fin 6799 df-pnf 8058 df-mnf 8059 df-xr 8060 df-ltxr 8061 df-le 8062 df-sub 8194 df-neg 8195 df-inn 8985 df-2 9043 df-n0 9244 df-z 9321 df-uz 9596 df-fz 10078 df-ihash 10850 |
This theorem is referenced by: (None) |
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