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Mirrors > Home > ILE Home > Th. List > velsn | GIF version |
Description: There is only one element in a singleton. Exercise 2 of [TakeutiZaring] p. 15. (Contributed by NM, 21-Jun-1993.) |
Ref | Expression |
---|---|
velsn | ⊢ (𝑥 ∈ {𝐴} ↔ 𝑥 = 𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | vex 2692 | . 2 ⊢ 𝑥 ∈ V | |
2 | 1 | elsn 3548 | 1 ⊢ (𝑥 ∈ {𝐴} ↔ 𝑥 = 𝐴) |
Colors of variables: wff set class |
Syntax hints: ↔ wb 104 = wceq 1332 ∈ wcel 1481 {csn 3532 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-io 699 ax-5 1424 ax-7 1425 ax-gen 1426 ax-ie1 1470 ax-ie2 1471 ax-8 1483 ax-10 1484 ax-11 1485 ax-i12 1486 ax-bndl 1487 ax-4 1488 ax-17 1507 ax-i9 1511 ax-ial 1515 ax-i5r 1516 ax-ext 2122 |
This theorem depends on definitions: df-bi 116 df-tru 1335 df-nf 1438 df-sb 1737 df-clab 2127 df-cleq 2133 df-clel 2136 df-nfc 2271 df-v 2691 df-sn 3538 |
This theorem is referenced by: dfpr2 3551 mosn 3567 ralsnsg 3568 ralsns 3569 rexsns 3570 disjsn 3593 snprc 3596 euabsn2 3600 prmg 3652 snss 3657 difprsnss 3666 eqsnm 3690 snsssn 3696 snsspw 3699 dfnfc2 3762 uni0b 3769 uni0c 3770 sndisj 3933 unidif0 4099 exmid01 4129 rext 4145 exss 4157 frirrg 4280 ordsucim 4424 ordtriexmidlem 4443 ordtri2or2exmidlem 4449 onsucelsucexmidlem 4452 elirr 4464 sucprcreg 4472 fconstmpt 4594 opeliunxp 4602 dmsnopg 5018 dfmpt3 5253 nfunsn 5463 fsn 5600 fnasrn 5606 fnasrng 5608 fconstfvm 5646 eusvobj2 5768 opabex3d 6027 opabex3 6028 dcdifsnid 6408 ecexr 6442 ixp0x 6628 xpsnen 6723 fidifsnen 6772 difinfsn 6993 exmidonfinlem 7066 iccid 9738 fzsn 9877 fzpr 9888 fzdifsuc 9892 fsum2dlemstep 11235 ef0lem 11403 1nprm 11831 restsn 12388 |
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