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Mirrors > Home > ILE Home > Th. List > ssomct | GIF version |
Description: A decidable subset of ω is countable. (Contributed by Jim Kingdon, 19-Sep-2024.) |
Ref | Expression |
---|---|
ssomct | ⊢ ((𝐴 ⊆ ω ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴) → ∃𝑓 𝑓:ω–onto→(𝐴 ⊔ 1o)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | omex 4555 | . . . . 5 ⊢ ω ∈ V | |
2 | 1 | ssex 4104 | . . . 4 ⊢ (𝐴 ⊆ ω → 𝐴 ∈ V) |
3 | 2 | adantr 274 | . . 3 ⊢ ((𝐴 ⊆ ω ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴) → 𝐴 ∈ V) |
4 | simpl 108 | . . . 4 ⊢ ((𝐴 ⊆ ω ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴) → 𝐴 ⊆ ω) | |
5 | resiexg 4914 | . . . . . . 7 ⊢ (𝐴 ∈ V → ( I ↾ 𝐴) ∈ V) | |
6 | 2, 5 | syl 14 | . . . . . 6 ⊢ (𝐴 ⊆ ω → ( I ↾ 𝐴) ∈ V) |
7 | 6 | adantr 274 | . . . . 5 ⊢ ((𝐴 ⊆ ω ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴) → ( I ↾ 𝐴) ∈ V) |
8 | f1oi 5455 | . . . . . 6 ⊢ ( I ↾ 𝐴):𝐴–1-1-onto→𝐴 | |
9 | f1ofo 5424 | . . . . . 6 ⊢ (( I ↾ 𝐴):𝐴–1-1-onto→𝐴 → ( I ↾ 𝐴):𝐴–onto→𝐴) | |
10 | 8, 9 | mp1i 10 | . . . . 5 ⊢ ((𝐴 ⊆ ω ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴) → ( I ↾ 𝐴):𝐴–onto→𝐴) |
11 | foeq1 5391 | . . . . 5 ⊢ (𝑓 = ( I ↾ 𝐴) → (𝑓:𝐴–onto→𝐴 ↔ ( I ↾ 𝐴):𝐴–onto→𝐴)) | |
12 | 7, 10, 11 | elabd 2857 | . . . 4 ⊢ ((𝐴 ⊆ ω ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴) → ∃𝑓 𝑓:𝐴–onto→𝐴) |
13 | simpr 109 | . . . 4 ⊢ ((𝐴 ⊆ ω ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴) → ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴) | |
14 | 4, 12, 13 | 3jca 1162 | . . 3 ⊢ ((𝐴 ⊆ ω ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴) → (𝐴 ⊆ ω ∧ ∃𝑓 𝑓:𝐴–onto→𝐴 ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴)) |
15 | sseq1 3151 | . . . 4 ⊢ (𝑦 = 𝐴 → (𝑦 ⊆ ω ↔ 𝐴 ⊆ ω)) | |
16 | foeq2 5392 | . . . . 5 ⊢ (𝑦 = 𝐴 → (𝑓:𝑦–onto→𝐴 ↔ 𝑓:𝐴–onto→𝐴)) | |
17 | 16 | exbidv 1805 | . . . 4 ⊢ (𝑦 = 𝐴 → (∃𝑓 𝑓:𝑦–onto→𝐴 ↔ ∃𝑓 𝑓:𝐴–onto→𝐴)) |
18 | eleq2 2221 | . . . . . 6 ⊢ (𝑦 = 𝐴 → (𝑥 ∈ 𝑦 ↔ 𝑥 ∈ 𝐴)) | |
19 | 18 | dcbid 824 | . . . . 5 ⊢ (𝑦 = 𝐴 → (DECID 𝑥 ∈ 𝑦 ↔ DECID 𝑥 ∈ 𝐴)) |
20 | 19 | ralbidv 2457 | . . . 4 ⊢ (𝑦 = 𝐴 → (∀𝑥 ∈ ω DECID 𝑥 ∈ 𝑦 ↔ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴)) |
21 | 15, 17, 20 | 3anbi123d 1294 | . . 3 ⊢ (𝑦 = 𝐴 → ((𝑦 ⊆ ω ∧ ∃𝑓 𝑓:𝑦–onto→𝐴 ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝑦) ↔ (𝐴 ⊆ ω ∧ ∃𝑓 𝑓:𝐴–onto→𝐴 ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴))) |
22 | 3, 14, 21 | elabd 2857 | . 2 ⊢ ((𝐴 ⊆ ω ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴) → ∃𝑦(𝑦 ⊆ ω ∧ ∃𝑓 𝑓:𝑦–onto→𝐴 ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝑦)) |
23 | ctssdc 7060 | . 2 ⊢ (∃𝑦(𝑦 ⊆ ω ∧ ∃𝑓 𝑓:𝑦–onto→𝐴 ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝑦) ↔ ∃𝑓 𝑓:ω–onto→(𝐴 ⊔ 1o)) | |
24 | 22, 23 | sylib 121 | 1 ⊢ ((𝐴 ⊆ ω ∧ ∀𝑥 ∈ ω DECID 𝑥 ∈ 𝐴) → ∃𝑓 𝑓:ω–onto→(𝐴 ⊔ 1o)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 103 DECID wdc 820 ∧ w3a 963 = wceq 1335 ∃wex 1472 ∈ wcel 2128 ∀wral 2435 Vcvv 2712 ⊆ wss 3102 I cid 4251 ωcom 4552 ↾ cres 4591 –onto→wfo 5171 –1-1-onto→wf1o 5172 1oc1o 6359 ⊔ cdju 6984 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 604 ax-in2 605 ax-io 699 ax-5 1427 ax-7 1428 ax-gen 1429 ax-ie1 1473 ax-ie2 1474 ax-8 1484 ax-10 1485 ax-11 1486 ax-i12 1487 ax-bndl 1489 ax-4 1490 ax-17 1506 ax-i9 1510 ax-ial 1514 ax-i5r 1515 ax-13 2130 ax-14 2131 ax-ext 2139 ax-coll 4082 ax-sep 4085 ax-nul 4093 ax-pow 4138 ax-pr 4172 ax-un 4396 ax-iinf 4550 |
This theorem depends on definitions: df-bi 116 df-dc 821 df-3an 965 df-tru 1338 df-fal 1341 df-nf 1441 df-sb 1743 df-eu 2009 df-mo 2010 df-clab 2144 df-cleq 2150 df-clel 2153 df-nfc 2288 df-ne 2328 df-ral 2440 df-rex 2441 df-reu 2442 df-rab 2444 df-v 2714 df-sbc 2938 df-csb 3032 df-dif 3104 df-un 3106 df-in 3108 df-ss 3115 df-nul 3396 df-if 3507 df-pw 3546 df-sn 3567 df-pr 3568 df-op 3570 df-uni 3775 df-int 3810 df-iun 3853 df-br 3968 df-opab 4029 df-mpt 4030 df-tr 4066 df-id 4256 df-iord 4329 df-on 4331 df-suc 4334 df-iom 4553 df-xp 4595 df-rel 4596 df-cnv 4597 df-co 4598 df-dm 4599 df-rn 4600 df-res 4601 df-ima 4602 df-iota 5138 df-fun 5175 df-fn 5176 df-f 5177 df-f1 5178 df-fo 5179 df-f1o 5180 df-fv 5181 df-1st 6091 df-2nd 6092 df-1o 6366 df-dju 6985 df-inl 6994 df-inr 6995 df-case 7031 |
This theorem is referenced by: ssnnctlemct 12271 |
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