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Mirrors > Home > MPE Home > Th. List > unifi2 | Structured version Visualization version GIF version |
Description: The finite union of finite sets is finite. Exercise 13 of [Enderton] p. 144. This version of unifi 8530 is useful only if we assume the Axiom of Infinity (see comments in fin2inf 8498). (Contributed by NM, 11-Mar-2006.) |
Ref | Expression |
---|---|
unifi2 | ⊢ ((𝐴 ≺ ω ∧ ∀𝑥 ∈ 𝐴 𝑥 ≺ ω) → ∪ 𝐴 ≺ ω) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | isfinite2 8493 | . . 3 ⊢ (𝐴 ≺ ω → 𝐴 ∈ Fin) | |
2 | isfinite2 8493 | . . . . 5 ⊢ (𝑥 ≺ ω → 𝑥 ∈ Fin) | |
3 | 2 | ralimi 3161 | . . . 4 ⊢ (∀𝑥 ∈ 𝐴 𝑥 ≺ ω → ∀𝑥 ∈ 𝐴 𝑥 ∈ Fin) |
4 | dfss3 3816 | . . . 4 ⊢ (𝐴 ⊆ Fin ↔ ∀𝑥 ∈ 𝐴 𝑥 ∈ Fin) | |
5 | 3, 4 | sylibr 226 | . . 3 ⊢ (∀𝑥 ∈ 𝐴 𝑥 ≺ ω → 𝐴 ⊆ Fin) |
6 | unifi 8530 | . . 3 ⊢ ((𝐴 ∈ Fin ∧ 𝐴 ⊆ Fin) → ∪ 𝐴 ∈ Fin) | |
7 | 1, 5, 6 | syl2an 589 | . 2 ⊢ ((𝐴 ≺ ω ∧ ∀𝑥 ∈ 𝐴 𝑥 ≺ ω) → ∪ 𝐴 ∈ Fin) |
8 | fin2inf 8498 | . . . 4 ⊢ (𝐴 ≺ ω → ω ∈ V) | |
9 | 8 | adantr 474 | . . 3 ⊢ ((𝐴 ≺ ω ∧ ∀𝑥 ∈ 𝐴 𝑥 ≺ ω) → ω ∈ V) |
10 | isfiniteg 8495 | . . 3 ⊢ (ω ∈ V → (∪ 𝐴 ∈ Fin ↔ ∪ 𝐴 ≺ ω)) | |
11 | 9, 10 | syl 17 | . 2 ⊢ ((𝐴 ≺ ω ∧ ∀𝑥 ∈ 𝐴 𝑥 ≺ ω) → (∪ 𝐴 ∈ Fin ↔ ∪ 𝐴 ≺ ω)) |
12 | 7, 11 | mpbid 224 | 1 ⊢ ((𝐴 ≺ ω ∧ ∀𝑥 ∈ 𝐴 𝑥 ≺ ω) → ∪ 𝐴 ≺ ω) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 198 ∧ wa 386 ∈ wcel 2164 ∀wral 3117 Vcvv 3414 ⊆ wss 3798 ∪ cuni 4660 class class class wbr 4875 ωcom 7331 ≺ csdm 8227 Fincfn 8228 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1894 ax-4 1908 ax-5 2009 ax-6 2075 ax-7 2112 ax-8 2166 ax-9 2173 ax-10 2192 ax-11 2207 ax-12 2220 ax-13 2389 ax-ext 2803 ax-sep 5007 ax-nul 5015 ax-pow 5067 ax-pr 5129 ax-un 7214 |
This theorem depends on definitions: df-bi 199 df-an 387 df-or 879 df-3or 1112 df-3an 1113 df-tru 1660 df-ex 1879 df-nf 1883 df-sb 2068 df-mo 2605 df-eu 2640 df-clab 2812 df-cleq 2818 df-clel 2821 df-nfc 2958 df-ne 3000 df-ral 3122 df-rex 3123 df-reu 3124 df-rab 3126 df-v 3416 df-sbc 3663 df-csb 3758 df-dif 3801 df-un 3803 df-in 3805 df-ss 3812 df-pss 3814 df-nul 4147 df-if 4309 df-pw 4382 df-sn 4400 df-pr 4402 df-tp 4404 df-op 4406 df-uni 4661 df-int 4700 df-iun 4744 df-br 4876 df-opab 4938 df-mpt 4955 df-tr 4978 df-id 5252 df-eprel 5257 df-po 5265 df-so 5266 df-fr 5305 df-we 5307 df-xp 5352 df-rel 5353 df-cnv 5354 df-co 5355 df-dm 5356 df-rn 5357 df-res 5358 df-ima 5359 df-pred 5924 df-ord 5970 df-on 5971 df-lim 5972 df-suc 5973 df-iota 6090 df-fun 6129 df-fn 6130 df-f 6131 df-f1 6132 df-fo 6133 df-f1o 6134 df-fv 6135 df-ov 6913 df-oprab 6914 df-mpt2 6915 df-om 7332 df-wrecs 7677 df-recs 7739 df-rdg 7777 df-1o 7831 df-oadd 7835 df-er 8014 df-en 8229 df-dom 8230 df-sdom 8231 df-fin 8232 |
This theorem is referenced by: (None) |
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