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Mirrors > Home > MPE Home > Th. List > n0i | Structured version Visualization version GIF version |
Description: If a class has elements, then it is not empty. (Contributed by NM, 31-Dec-1993.) |
Ref | Expression |
---|---|
n0i | ⊢ (𝐵 ∈ 𝐴 → ¬ 𝐴 = ∅) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | noel 4296 | . . 3 ⊢ ¬ 𝐵 ∈ ∅ | |
2 | eleq2 2901 | . . 3 ⊢ (𝐴 = ∅ → (𝐵 ∈ 𝐴 ↔ 𝐵 ∈ ∅)) | |
3 | 1, 2 | mtbiri 329 | . 2 ⊢ (𝐴 = ∅ → ¬ 𝐵 ∈ 𝐴) |
4 | 3 | con2i 141 | 1 ⊢ (𝐵 ∈ 𝐴 → ¬ 𝐴 = ∅) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 = wceq 1537 ∈ wcel 2114 ∅c0 4291 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2116 ax-9 2124 ax-ext 2793 |
This theorem depends on definitions: df-bi 209 df-an 399 df-ex 1781 df-sb 2070 df-clab 2800 df-cleq 2814 df-clel 2893 df-dif 3939 df-nul 4292 |
This theorem is referenced by: ne0i 4300 n0ii 4302 oprcl 4829 disjss3 5065 elfvdm 6702 mptrcl 6777 isomin 7090 ovrcl 7197 oalimcl 8186 omlimcl 8204 oaabs2 8272 ecexr 8294 elpmi 8425 elmapex 8427 pmresg 8434 pmsspw 8441 ixpssmap2g 8491 ixpssmapg 8492 resixpfo 8500 php3 8703 cantnfp1lem2 9142 cantnflem1 9152 cnfcom2lem 9164 rankxplim2 9309 rankxplim3 9310 cardlim 9401 alephnbtwn 9497 ttukeylem5 9935 r1wunlim 10159 ssnn0fi 13354 ruclem13 15595 ramtub 16348 elbasfv 16544 elbasov 16545 restsspw 16705 homarcl 17288 grpidval 17871 odlem2 18667 efgrelexlema 18875 subcmn 18957 dvdsrval 19395 pf1rcl 20512 elocv 20812 matrcl 21021 0top 21591 ppttop 21615 pptbas 21616 restrcl 21765 ssrest 21784 iscnp2 21847 lmmo 21988 zfbas 22504 rnelfmlem 22560 isfcls 22617 isnghm 23332 iscau2 23880 itg2cnlem1 24362 itgsubstlem 24645 dchrrcl 25816 clwwlknnn 27811 ssmxidllem 30978 eulerpartlemgvv 31634 indispconn 32481 cvmtop1 32507 cvmtop2 32508 mrsub0 32763 mrsubf 32764 mrsubccat 32765 mrsubcn 32766 mrsubco 32768 mrsubvrs 32769 msubf 32779 mclsrcl 32808 funpartlem 33403 tailfb 33725 nlpineqsn 34692 atbase 36440 llnbase 36660 lplnbase 36685 lvolbase 36729 osumcllem4N 37110 pexmidlem1N 37121 lhpbase 37149 mapco2g 39360 wepwsolem 39691 uneqsn 40422 ssfiunibd 41625 hoicvr 42879 0nelsetpreimafv 43599 |
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