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Mirrors > Home > MPE Home > Th. List > cardsn | Structured version Visualization version GIF version |
Description: A singleton has cardinality one. (Contributed by Mario Carneiro, 10-Jan-2013.) |
Ref | Expression |
---|---|
cardsn | β’ (π΄ β π β (cardβ{π΄}) = 1o) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eqid 2724 | . . 3 β’ {π΄} = {π΄} | |
2 | sneq 4631 | . . . . 5 β’ (π₯ = π΄ β {π₯} = {π΄}) | |
3 | 2 | eqeq2d 2735 | . . . 4 β’ (π₯ = π΄ β ({π΄} = {π₯} β {π΄} = {π΄})) |
4 | 3 | spcegv 3579 | . . 3 β’ (π΄ β π β ({π΄} = {π΄} β βπ₯{π΄} = {π₯})) |
5 | 1, 4 | mpi 20 | . 2 β’ (π΄ β π β βπ₯{π΄} = {π₯}) |
6 | card1 9960 | . 2 β’ ((cardβ{π΄}) = 1o β βπ₯{π΄} = {π₯}) | |
7 | 5, 6 | sylibr 233 | 1 β’ (π΄ β π β (cardβ{π΄}) = 1o) |
Colors of variables: wff setvar class |
Syntax hints: β wi 4 = wceq 1533 βwex 1773 β wcel 2098 {csn 4621 βcfv 6534 1oc1o 8455 cardccrd 9927 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1789 ax-4 1803 ax-5 1905 ax-6 1963 ax-7 2003 ax-8 2100 ax-9 2108 ax-10 2129 ax-11 2146 ax-12 2163 ax-ext 2695 ax-sep 5290 ax-nul 5297 ax-pow 5354 ax-pr 5418 ax-un 7719 |
This theorem depends on definitions: df-bi 206 df-an 396 df-or 845 df-3or 1085 df-3an 1086 df-tru 1536 df-fal 1546 df-ex 1774 df-nf 1778 df-sb 2060 df-mo 2526 df-eu 2555 df-clab 2702 df-cleq 2716 df-clel 2802 df-nfc 2877 df-ne 2933 df-ral 3054 df-rex 3063 df-reu 3369 df-rab 3425 df-v 3468 df-sbc 3771 df-csb 3887 df-dif 3944 df-un 3946 df-in 3948 df-ss 3958 df-pss 3960 df-nul 4316 df-if 4522 df-pw 4597 df-sn 4622 df-pr 4624 df-op 4628 df-uni 4901 df-int 4942 df-br 5140 df-opab 5202 df-mpt 5223 df-tr 5257 df-id 5565 df-eprel 5571 df-po 5579 df-so 5580 df-fr 5622 df-we 5624 df-xp 5673 df-rel 5674 df-cnv 5675 df-co 5676 df-dm 5677 df-rn 5678 df-res 5679 df-ima 5680 df-ord 6358 df-on 6359 df-lim 6360 df-suc 6361 df-iota 6486 df-fun 6536 df-fn 6537 df-f 6538 df-f1 6539 df-fo 6540 df-f1o 6541 df-fv 6542 df-om 7850 df-1o 8462 df-er 8700 df-en 8937 df-dom 8938 df-sdom 8939 df-fin 8940 df-card 9931 |
This theorem is referenced by: ackbij1lem14 10225 cfsuc 10249 |
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