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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 8906 | . . . . 5 ⊢ (𝐵 ≼ ω → 𝐵 ∈ V) | |
2 | 1 | adantl 483 | . . . 4 ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → 𝐵 ∈ V) |
3 | simpl 484 | . . . 4 ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → 𝐴 ≼ ω) | |
4 | xpdom1g 9016 | . . . 4 ⊢ ((𝐵 ∈ V ∧ 𝐴 ≼ ω) → (𝐴 × 𝐵) ≼ (ω × 𝐵)) | |
5 | 2, 3, 4 | syl2anc 585 | . . 3 ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → (𝐴 × 𝐵) ≼ (ω × 𝐵)) |
6 | omex 9584 | . . . . 5 ⊢ ω ∈ V | |
7 | 6 | xpdom2 9014 | . . . 4 ⊢ (𝐵 ≼ ω → (ω × 𝐵) ≼ (ω × ω)) |
8 | 7 | adantl 483 | . . 3 ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → (ω × 𝐵) ≼ (ω × ω)) |
9 | domtr 8950 | . . 3 ⊢ (((𝐴 × 𝐵) ≼ (ω × 𝐵) ∧ (ω × 𝐵) ≼ (ω × ω)) → (𝐴 × 𝐵) ≼ (ω × ω)) | |
10 | 5, 8, 9 | syl2anc 585 | . 2 ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → (𝐴 × 𝐵) ≼ (ω × ω)) |
11 | xpomen 9956 | . 2 ⊢ (ω × ω) ≈ ω | |
12 | domentr 8956 | . 2 ⊢ (((𝐴 × 𝐵) ≼ (ω × ω) ∧ (ω × ω) ≈ ω) → (𝐴 × 𝐵) ≼ ω) | |
13 | 10, 11, 12 | sylancl 587 | 1 ⊢ ((𝐴 ≼ ω ∧ 𝐵 ≼ ω) → (𝐴 × 𝐵) ≼ ω) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∧ wa 397 ∈ wcel 2107 Vcvv 3444 class class class wbr 5106 × cxp 5632 ωcom 7803 ≈ cen 8883 ≼ cdom 8884 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1798 ax-4 1812 ax-5 1914 ax-6 1972 ax-7 2012 ax-8 2109 ax-9 2117 ax-10 2138 ax-11 2155 ax-12 2172 ax-ext 2704 ax-rep 5243 ax-sep 5257 ax-nul 5264 ax-pow 5321 ax-pr 5385 ax-un 7673 ax-inf2 9582 |
This theorem depends on definitions: df-bi 206 df-an 398 df-or 847 df-3or 1089 df-3an 1090 df-tru 1545 df-fal 1555 df-ex 1783 df-nf 1787 df-sb 2069 df-mo 2535 df-eu 2564 df-clab 2711 df-cleq 2725 df-clel 2811 df-nfc 2886 df-ne 2941 df-ral 3062 df-rex 3071 df-rmo 3352 df-reu 3353 df-rab 3407 df-v 3446 df-sbc 3741 df-csb 3857 df-dif 3914 df-un 3916 df-in 3918 df-ss 3928 df-pss 3930 df-nul 4284 df-if 4488 df-pw 4563 df-sn 4588 df-pr 4590 df-op 4594 df-uni 4867 df-int 4909 df-iun 4957 df-br 5107 df-opab 5169 df-mpt 5190 df-tr 5224 df-id 5532 df-eprel 5538 df-po 5546 df-so 5547 df-fr 5589 df-se 5590 df-we 5591 df-xp 5640 df-rel 5641 df-cnv 5642 df-co 5643 df-dm 5644 df-rn 5645 df-res 5646 df-ima 5647 df-pred 6254 df-ord 6321 df-on 6322 df-lim 6323 df-suc 6324 df-iota 6449 df-fun 6499 df-fn 6500 df-f 6501 df-f1 6502 df-fo 6503 df-f1o 6504 df-fv 6505 df-isom 6506 df-riota 7314 df-ov 7361 df-om 7804 df-1st 7922 df-2nd 7923 df-frecs 8213 df-wrecs 8244 df-recs 8318 df-rdg 8357 df-1o 8413 df-er 8651 df-en 8887 df-dom 8888 df-sdom 8889 df-fin 8890 df-oi 9451 df-card 9880 |
This theorem is referenced by: tx1stc 23017 mpocti 31679 mpct 43509 opnvonmbllem2 44960 smflimlem6 45103 smfpimbor1lem1 45125 |
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