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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 2560 | . 2 ⊢ 𝑥 ∈ V | |
2 | 1 | elsn 3391 | 1 ⊢ (𝑥 ∈ {𝐴} ↔ 𝑥 = 𝐴) |
Colors of variables: wff set class |
Syntax hints: ↔ wb 98 = wceq 1243 ∈ wcel 1393 {csn 3375 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 99 ax-ia2 100 ax-ia3 101 ax-io 630 ax-5 1336 ax-7 1337 ax-gen 1338 ax-ie1 1382 ax-ie2 1383 ax-8 1395 ax-10 1396 ax-11 1397 ax-i12 1398 ax-bndl 1399 ax-4 1400 ax-17 1419 ax-i9 1423 ax-ial 1427 ax-i5r 1428 ax-ext 2022 |
This theorem depends on definitions: df-bi 110 df-tru 1246 df-nf 1350 df-sb 1646 df-clab 2027 df-cleq 2033 df-clel 2036 df-nfc 2167 df-v 2559 df-sn 3381 |
This theorem is referenced by: dfpr2 3394 mosn 3406 ralsnsg 3407 ralsns 3408 rexsns 3409 rexsnsOLD 3410 disjsn 3432 snprc 3435 euabsn2 3439 prmg 3489 snss 3494 difprsnss 3502 eqsnm 3526 snsssn 3532 snsspw 3535 dfnfc2 3598 uni0b 3605 uni0c 3606 sndisj 3760 unidif0 3920 rext 3951 exss 3963 frirrg 4087 ordsucim 4226 ordtriexmidlem 4245 ordtri2or2exmidlem 4251 onsucelsucexmidlem 4254 elirr 4266 sucprcreg 4273 fconstmpt 4387 opeliunxp 4395 dmsnopg 4792 dfmpt3 5021 nfunsn 5207 fsn 5335 fnasrn 5341 fnasrng 5343 fconstfvm 5379 eusvobj2 5498 opabex3d 5748 opabex3 5749 nndifsnid 6080 ecexr 6111 xpsnen 6295 fidifsnen 6331 fidifsnid 6332 iccid 8794 fzsn 8929 fzpr 8939 fzdifsuc 8943 |
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