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Mirrors > Home > MPE Home > Th. List > xpct | Structured version Visualization version GIF version |
Description: The cartesian product of two countable sets is countable. (Contributed by Thierry Arnoux, 24-Sep-2017.) |
Ref | Expression |
---|---|
xpct | ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → (𝐴 × 𝐵) ≼ ω) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ctex 8708 | . . . . 5 ⊢ (𝐵 ≼ ω → 𝐵 ∈ V) | |
2 | 1 | adantl 481 | . . . 4 ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → 𝐵 ∈ V) |
3 | simpl 482 | . . . 4 ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → 𝐴 ≼ ω) | |
4 | xpdom1g 8809 | . . . 4 ⊢ ((𝐵 ∈ V ∧ 𝐴 ≼ ω) → (𝐴 × 𝐵) ≼ (ω × 𝐵)) | |
5 | 2, 3, 4 | syl2anc 583 | . . 3 ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → (𝐴 × 𝐵) ≼ (ω × 𝐵)) |
6 | omex 9331 | . . . . 5 ⊢ ω ∈ V | |
7 | 6 | xpdom2 8807 | . . . 4 ⊢ (𝐵 ≼ ω → (ω × 𝐵) ≼ (ω × ω)) |
8 | 7 | adantl 481 | . . 3 ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → (ω × 𝐵) ≼ (ω × ω)) |
9 | domtr 8748 | . . 3 ⊢ (((𝐴 × 𝐵) ≼ (ω × 𝐵) ∧ (ω × 𝐵) ≼ (ω × ω)) → (𝐴 × 𝐵) ≼ (ω × ω)) | |
10 | 5, 8, 9 | syl2anc 583 | . 2 ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → (𝐴 × 𝐵) ≼ (ω × ω)) |
11 | xpomen 9702 | . 2 ⊢ (ω × ω) ≈ ω | |
12 | domentr 8754 | . 2 ⊢ (((𝐴 × 𝐵) ≼ (ω × ω) ∧ (ω × ω) ≈ ω) → (𝐴 × 𝐵) ≼ ω) | |
13 | 10, 11, 12 | sylancl 585 | 1 ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → (𝐴 × 𝐵) ≼ ω) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∧ wa 395 ∈ wcel 2108 Vcvv 3422 class class class wbr 5070 × cxp 5578 ωcom 7687 ≈ cen 8688 ≼ cdom 8689 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1799 ax-4 1813 ax-5 1914 ax-6 1972 ax-7 2012 ax-8 2110 ax-9 2118 ax-10 2139 ax-11 2156 ax-12 2173 ax-ext 2709 ax-rep 5205 ax-sep 5218 ax-nul 5225 ax-pow 5283 ax-pr 5347 ax-un 7566 ax-inf2 9329 |
This theorem depends on definitions: df-bi 206 df-an 396 df-or 844 df-3or 1086 df-3an 1087 df-tru 1542 df-fal 1552 df-ex 1784 df-nf 1788 df-sb 2069 df-mo 2540 df-eu 2569 df-clab 2716 df-cleq 2730 df-clel 2817 df-nfc 2888 df-ne 2943 df-ral 3068 df-rex 3069 df-reu 3070 df-rmo 3071 df-rab 3072 df-v 3424 df-sbc 3712 df-csb 3829 df-dif 3886 df-un 3888 df-in 3890 df-ss 3900 df-pss 3902 df-nul 4254 df-if 4457 df-pw 4532 df-sn 4559 df-pr 4561 df-tp 4563 df-op 4565 df-uni 4837 df-int 4877 df-iun 4923 df-br 5071 df-opab 5133 df-mpt 5154 df-tr 5188 df-id 5480 df-eprel 5486 df-po 5494 df-so 5495 df-fr 5535 df-se 5536 df-we 5537 df-xp 5586 df-rel 5587 df-cnv 5588 df-co 5589 df-dm 5590 df-rn 5591 df-res 5592 df-ima 5593 df-pred 6191 df-ord 6254 df-on 6255 df-lim 6256 df-suc 6257 df-iota 6376 df-fun 6420 df-fn 6421 df-f 6422 df-f1 6423 df-fo 6424 df-f1o 6425 df-fv 6426 df-isom 6427 df-riota 7212 df-ov 7258 df-om 7688 df-1st 7804 df-2nd 7805 df-frecs 8068 df-wrecs 8099 df-recs 8173 df-rdg 8212 df-1o 8267 df-er 8456 df-en 8692 df-dom 8693 df-sdom 8694 df-fin 8695 df-oi 9199 df-card 9628 |
This theorem is referenced by: tx1stc 22709 mpocti 30952 mpct 42630 opnvonmbllem2 44061 smflimlem6 44198 smfpimbor1lem1 44219 |
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