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Mirrors > Home > MPE Home > Th. List > dfsn2 | Structured version Visualization version GIF version |
Description: Alternate definition of singleton. Definition 5.1 of [TakeutiZaring] p. 15. (Contributed by NM, 24-Apr-1994.) |
Ref | Expression |
---|---|
dfsn2 | ⊢ {𝐴} = {𝐴, 𝐴} |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-pr 4528 | . 2 ⊢ {𝐴, 𝐴} = ({𝐴} ∪ {𝐴}) | |
2 | unidm 4079 | . 2 ⊢ ({𝐴} ∪ {𝐴}) = {𝐴} | |
3 | 1, 2 | eqtr2i 2822 | 1 ⊢ {𝐴} = {𝐴, 𝐴} |
Colors of variables: wff setvar class |
Syntax hints: = wceq 1538 ∪ cun 3879 {csn 4525 {cpr 4527 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2113 ax-9 2121 ax-ext 2770 |
This theorem depends on definitions: df-bi 210 df-an 400 df-or 845 df-ex 1782 df-sb 2070 df-clab 2777 df-cleq 2791 df-clel 2870 df-v 3443 df-un 3886 df-pr 4528 |
This theorem is referenced by: nfsn 4603 disjprsn 4610 tpidm12 4651 tpidm 4654 ifpprsnss 4660 preqsnd 4749 elpreqprlem 4756 opidg 4784 unisng 4819 intsng 4873 snex 5297 opeqsng 5358 propeqop 5362 relop 5685 funopg 6358 f1oprswap 6633 fnprb 6948 enpr1g 8558 supsn 8920 infsn 8953 prdom2 9417 wuntp 10122 wunsn 10127 grusn 10215 prunioo 12859 hashprg 13752 hashfun 13794 hashle2pr 13831 lcmfsn 15969 lubsn 17696 indislem 21605 hmphindis 22402 wilthlem2 25654 upgrex 26885 umgrnloop0 26902 edglnl 26936 usgrnloop0ALT 26995 uspgr1v1eop 27039 1loopgruspgr 27290 1egrvtxdg0 27301 umgr2v2eedg 27314 umgr2v2e 27315 ifpsnprss 27412 upgriswlk 27430 clwwlkn1 27826 upgr1wlkdlem1 27930 1to2vfriswmgr 28064 esumpr2 31436 dvh2dim 38741 wopprc 39971 clsk1indlem4 40747 sge0prle 43040 meadjun 43101 elsprel 43992 upgrwlkupwlk 44368 |
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