Metamath Proof Explorer |
< Previous
Next >
Nearby theorems |
||
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 8815 is useful only if we assume the Axiom of Infinity (see comments in fin2inf 8783). (Contributed by NM, 11-Mar-2006.) |
Ref | Expression |
---|---|
unifi2 | ⊢ ((𝐴 ≺ ω ∧ ∀𝑥 ∈ 𝐴 𝑥 ≺ ω) → ∪ 𝐴 ≺ ω) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | isfinite2 8778 | . . 3 ⊢ (𝐴 ≺ ω → 𝐴 ∈ Fin) | |
2 | isfinite2 8778 | . . . . 5 ⊢ (𝑥 ≺ ω → 𝑥 ∈ Fin) | |
3 | 2 | ralimi 3162 | . . . 4 ⊢ (∀𝑥 ∈ 𝐴 𝑥 ≺ ω → ∀𝑥 ∈ 𝐴 𝑥 ∈ Fin) |
4 | dfss3 3958 | . . . 4 ⊢ (𝐴 ⊆ Fin ↔ ∀𝑥 ∈ 𝐴 𝑥 ∈ Fin) | |
5 | 3, 4 | sylibr 236 | . . 3 ⊢ (∀𝑥 ∈ 𝐴 𝑥 ≺ ω → 𝐴 ⊆ Fin) |
6 | unifi 8815 | . . 3 ⊢ ((𝐴 ∈ Fin ∧ 𝐴 ⊆ Fin) → ∪ 𝐴 ∈ Fin) | |
7 | 1, 5, 6 | syl2an 597 | . 2 ⊢ ((𝐴 ≺ ω ∧ ∀𝑥 ∈ 𝐴 𝑥 ≺ ω) → ∪ 𝐴 ∈ Fin) |
8 | fin2inf 8783 | . . . 4 ⊢ (𝐴 ≺ ω → ω ∈ V) | |
9 | 8 | adantr 483 | . . 3 ⊢ ((𝐴 ≺ ω ∧ ∀𝑥 ∈ 𝐴 𝑥 ≺ ω) → ω ∈ V) |
10 | isfiniteg 8780 | . . 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 234 | 1 ⊢ ((𝐴 ≺ ω ∧ ∀𝑥 ∈ 𝐴 𝑥 ≺ ω) → ∪ 𝐴 ≺ ω) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 208 ∧ wa 398 ∈ wcel 2114 ∀wral 3140 Vcvv 3496 ⊆ wss 3938 ∪ cuni 4840 class class class wbr 5068 ωcom 7582 ≺ csdm 8510 Fincfn 8511 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2116 ax-9 2124 ax-10 2145 ax-11 2161 ax-12 2177 ax-ext 2795 ax-sep 5205 ax-nul 5212 ax-pow 5268 ax-pr 5332 ax-un 7463 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1540 df-ex 1781 df-nf 1785 df-sb 2070 df-mo 2622 df-eu 2654 df-clab 2802 df-cleq 2816 df-clel 2895 df-nfc 2965 df-ne 3019 df-ral 3145 df-rex 3146 df-reu 3147 df-rab 3149 df-v 3498 df-sbc 3775 df-csb 3886 df-dif 3941 df-un 3943 df-in 3945 df-ss 3954 df-pss 3956 df-nul 4294 df-if 4470 df-pw 4543 df-sn 4570 df-pr 4572 df-tp 4574 df-op 4576 df-uni 4841 df-int 4879 df-iun 4923 df-br 5069 df-opab 5131 df-mpt 5149 df-tr 5175 df-id 5462 df-eprel 5467 df-po 5476 df-so 5477 df-fr 5516 df-we 5518 df-xp 5563 df-rel 5564 df-cnv 5565 df-co 5566 df-dm 5567 df-rn 5568 df-res 5569 df-ima 5570 df-pred 6150 df-ord 6196 df-on 6197 df-lim 6198 df-suc 6199 df-iota 6316 df-fun 6359 df-fn 6360 df-f 6361 df-f1 6362 df-fo 6363 df-f1o 6364 df-fv 6365 df-ov 7161 df-oprab 7162 df-mpo 7163 df-om 7583 df-wrecs 7949 df-recs 8010 df-rdg 8048 df-1o 8104 df-oadd 8108 df-er 8291 df-en 8512 df-dom 8513 df-sdom 8514 df-fin 8515 |
This theorem is referenced by: (None) |
Copyright terms: Public domain | W3C validator |