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Mirrors > Home > MPE Home > Th. List > unisng | Structured version Visualization version GIF version |
Description: A set equals the union of its singleton. Theorem 8.2 of [Quine] p. 53. (Contributed by NM, 13-Aug-2002.) |
Ref | Expression |
---|---|
unisng | ⊢ (𝐴 ∈ 𝑉 → ∪ {𝐴} = 𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dfsn2 4642 | . . . 4 ⊢ {𝐴} = {𝐴, 𝐴} | |
2 | 1 | unieqi 4922 | . . 3 ⊢ ∪ {𝐴} = ∪ {𝐴, 𝐴} |
3 | 2 | a1i 11 | . 2 ⊢ (𝐴 ∈ 𝑉 → ∪ {𝐴} = ∪ {𝐴, 𝐴}) |
4 | uniprg 4926 | . . 3 ⊢ ((𝐴 ∈ 𝑉 ∧ 𝐴 ∈ 𝑉) → ∪ {𝐴, 𝐴} = (𝐴 ∪ 𝐴)) | |
5 | 4 | anidms 568 | . 2 ⊢ (𝐴 ∈ 𝑉 → ∪ {𝐴, 𝐴} = (𝐴 ∪ 𝐴)) |
6 | unidm 4153 | . . 3 ⊢ (𝐴 ∪ 𝐴) = 𝐴 | |
7 | 6 | a1i 11 | . 2 ⊢ (𝐴 ∈ 𝑉 → (𝐴 ∪ 𝐴) = 𝐴) |
8 | 3, 5, 7 | 3eqtrd 2777 | 1 ⊢ (𝐴 ∈ 𝑉 → ∪ {𝐴} = 𝐴) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 = wceq 1542 ∈ wcel 2107 ∪ cun 3947 {csn 4629 {cpr 4631 ∪ cuni 4909 |
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-ext 2704 |
This theorem depends on definitions: df-bi 206 df-an 398 df-or 847 df-tru 1545 df-ex 1783 df-sb 2069 df-clab 2711 df-cleq 2725 df-clel 2811 df-v 3477 df-un 3954 df-in 3956 df-ss 3966 df-sn 4630 df-pr 4632 df-uni 4910 |
This theorem is referenced by: unisn 4931 unisn3 4933 dfnfc2 4934 unisn2 5313 unisucs 6442 en2other2 10004 pmtrprfv 19321 dprdsn 19906 indistopon 22504 ordtuni 22694 cmpcld 22906 ptcmplem5 23560 cldsubg 23615 icccmplem2 24339 vmappw 26620 chsupsn 30666 xrge0tsmseq 32211 cycpm2tr 32278 qustrivr 32477 esumsnf 33062 prsiga 33129 rossros 33178 cvmscld 34264 unisnif 34897 topjoin 35250 fnejoin2 35254 bj-snmoore 35994 pibt2 36298 heiborlem8 36686 sucunisn 42121 onsucunitp 42123 oaun3 42132 fourierdlem80 44902 |
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