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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 4247 | . . 3 ⊢ ¬ 𝐵 ∈ ∅ | |
2 | eleq2 2878 | . . 3 ⊢ (𝐴 = ∅ → (𝐵 ∈ 𝐴 ↔ 𝐵 ∈ ∅)) | |
3 | 1, 2 | mtbiri 330 | . 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 1538 ∈ wcel 2111 ∅c0 4243 |
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-ex 1782 df-sb 2070 df-clab 2777 df-cleq 2791 df-clel 2870 df-dif 3884 df-nul 4244 |
This theorem is referenced by: ne0i 4250 n0ii 4252 oprcl 4791 disjss3 5029 elfvdm 6677 mptrcl 6754 isomin 7069 ovrcl 7176 oalimcl 8169 omlimcl 8187 oaabs2 8255 ecexr 8277 elpmi 8408 elmapex 8410 pmresg 8417 pmsspw 8424 ixpssmap2g 8474 ixpssmapg 8475 resixpfo 8483 php3 8687 cantnfp1lem2 9126 cantnflem1 9136 cnfcom2lem 9148 rankxplim2 9293 rankxplim3 9294 cardlim 9385 alephnbtwn 9482 ttukeylem5 9924 r1wunlim 10148 ssnn0fi 13348 ruclem13 15587 ramtub 16338 elbasfv 16536 elbasov 16537 restsspw 16697 homarcl 17280 grpidval 17863 odlem2 18659 efgrelexlema 18867 subcmn 18950 dvdsrval 19391 elocv 20357 pf1rcl 20973 matrcl 21017 0top 21588 ppttop 21612 pptbas 21613 restrcl 21762 ssrest 21781 iscnp2 21844 lmmo 21985 zfbas 22501 rnelfmlem 22557 isfcls 22614 isnghm 23329 iscau2 23881 itg2cnlem1 24365 itgsubstlem 24651 dchrrcl 25824 clwwlknnn 27818 ssmxidllem 31049 eulerpartlemgvv 31744 indispconn 32594 cvmtop1 32620 cvmtop2 32621 mrsub0 32876 mrsubf 32877 mrsubccat 32878 mrsubcn 32879 mrsubco 32881 mrsubvrs 32882 msubf 32892 mclsrcl 32921 funpartlem 33516 tailfb 33838 nlpineqsn 34825 atbase 36585 llnbase 36805 lplnbase 36830 lvolbase 36874 osumcllem4N 37255 pexmidlem1N 37266 lhpbase 37294 mapco2g 39655 wepwsolem 39986 uneqsn 40726 ssfiunibd 41941 hoicvr 43187 0nelsetpreimafv 43907 |
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