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Mirrors > Home > ILE Home > Th. List > euen1b | GIF version |
Description: Two ways to express "𝐴 has a unique element". (Contributed by Mario Carneiro, 9-Apr-2015.) |
Ref | Expression |
---|---|
euen1b | ⊢ (𝐴 ≈ 1𝑜 ↔ ∃!𝑥 𝑥 ∈ 𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | euen1 6509 | . 2 ⊢ (∃!𝑥 𝑥 ∈ 𝐴 ↔ {𝑥 ∣ 𝑥 ∈ 𝐴} ≈ 1𝑜) | |
2 | abid2 2208 | . . 3 ⊢ {𝑥 ∣ 𝑥 ∈ 𝐴} = 𝐴 | |
3 | 2 | breq1i 3850 | . 2 ⊢ ({𝑥 ∣ 𝑥 ∈ 𝐴} ≈ 1𝑜 ↔ 𝐴 ≈ 1𝑜) |
4 | 1, 3 | bitr2i 183 | 1 ⊢ (𝐴 ≈ 1𝑜 ↔ ∃!𝑥 𝑥 ∈ 𝐴) |
Colors of variables: wff set class |
Syntax hints: ↔ wb 103 ∈ wcel 1438 ∃!weu 1948 {cab 2074 class class class wbr 3843 1𝑜c1o 6166 ≈ cen 6445 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-in1 579 ax-in2 580 ax-io 665 ax-5 1381 ax-7 1382 ax-gen 1383 ax-ie1 1427 ax-ie2 1428 ax-8 1440 ax-10 1441 ax-11 1442 ax-i12 1443 ax-bndl 1444 ax-4 1445 ax-13 1449 ax-14 1450 ax-17 1464 ax-i9 1468 ax-ial 1472 ax-i5r 1473 ax-ext 2070 ax-sep 3955 ax-nul 3963 ax-pow 4007 ax-pr 4034 ax-un 4258 |
This theorem depends on definitions: df-bi 115 df-3an 926 df-tru 1292 df-nf 1395 df-sb 1693 df-eu 1951 df-mo 1952 df-clab 2075 df-cleq 2081 df-clel 2084 df-nfc 2217 df-ral 2364 df-rex 2365 df-reu 2366 df-rab 2368 df-v 2621 df-sbc 2841 df-dif 3001 df-un 3003 df-in 3005 df-ss 3012 df-nul 3287 df-pw 3429 df-sn 3450 df-pr 3451 df-op 3453 df-uni 3652 df-br 3844 df-opab 3898 df-id 4118 df-suc 4196 df-xp 4442 df-rel 4443 df-cnv 4444 df-co 4445 df-dm 4446 df-rn 4447 df-res 4448 df-ima 4449 df-iota 4975 df-fun 5012 df-fn 5013 df-f 5014 df-f1 5015 df-fo 5016 df-f1o 5017 df-fv 5018 df-1o 6173 df-en 6448 |
This theorem is referenced by: (None) |
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