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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 4180 | . 2 ⊢ {𝐴, 𝐴} = ({𝐴} ∪ {𝐴}) | |
2 | unidm 3756 | . 2 ⊢ ({𝐴} ∪ {𝐴}) = {𝐴} | |
3 | 1, 2 | eqtr2i 2645 | 1 ⊢ {𝐴} = {𝐴, 𝐴} |
Colors of variables: wff setvar class |
Syntax hints: = wceq 1483 ∪ cun 3572 {csn 4177 {cpr 4179 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1722 ax-4 1737 ax-5 1839 ax-6 1888 ax-7 1935 ax-9 1999 ax-10 2019 ax-11 2034 ax-12 2047 ax-13 2246 ax-ext 2602 |
This theorem depends on definitions: df-bi 197 df-or 385 df-an 386 df-tru 1486 df-ex 1705 df-nf 1710 df-sb 1881 df-clab 2609 df-cleq 2615 df-clel 2618 df-nfc 2753 df-v 3202 df-un 3579 df-pr 4180 |
This theorem is referenced by: nfsn 4242 disjprsn 4250 tpidm12 4290 tpidm 4293 ifpprsnss 4299 preqsnd 4392 preqsn 4393 preqsnOLD 4394 elpreqprlem 4395 opid 4421 unisn 4451 intsng 4512 snex 4908 opeqsn 4967 propeqop 4970 relop 5272 funopg 5922 f1oprswap 6180 fnprb 6472 enpr1g 8022 supsn 8378 infsn 8410 prdom2 8829 wuntp 9533 wunsn 9538 grusn 9626 prunioo 12301 hashprg 13182 hashprgOLD 13183 hashfun 13224 hashle2pr 13259 lcmfsn 15348 lubsn 17094 indislem 20804 hmphindis 21600 wilthlem2 24795 upgrex 25987 umgrnloop0 26004 edglnl 26038 usgrnloop0ALT 26097 uspgr1v1eop 26141 1loopgruspgr 26396 1egrvtxdg0 26407 umgr2v2eedg 26420 umgr2v2e 26421 ifpsnprss 26518 upgriswlk 26537 upgr1wlkdlem1 27005 1to2vfriswmgr 27143 esumpr2 30129 opidORIG 34109 dvh2dim 36734 wopprc 37597 clsk1indlem4 38342 sge0prle 40618 meadjun 40679 opidg 41297 upgrwlkupwlk 41721 elsprel 41725 |
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