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Mirrors > Home > MPE Home > Th. List > disjsn2 | Structured version Visualization version GIF version |
Description: Two distinct singletons are disjoint. (Contributed by NM, 25-May-1998.) |
Ref | Expression |
---|---|
disjsn2 | ⊢ (𝐴 ≠ 𝐵 → ({𝐴} ∩ {𝐵}) = ∅) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | elsni 4584 | . . . 4 ⊢ (𝐵 ∈ {𝐴} → 𝐵 = 𝐴) | |
2 | 1 | eqcomd 2827 | . . 3 ⊢ (𝐵 ∈ {𝐴} → 𝐴 = 𝐵) |
3 | 2 | necon3ai 3041 | . 2 ⊢ (𝐴 ≠ 𝐵 → ¬ 𝐵 ∈ {𝐴}) |
4 | disjsn 4647 | . 2 ⊢ (({𝐴} ∩ {𝐵}) = ∅ ↔ ¬ 𝐵 ∈ {𝐴}) | |
5 | 3, 4 | sylibr 236 | 1 ⊢ (𝐴 ≠ 𝐵 → ({𝐴} ∩ {𝐵}) = ∅) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 = wceq 1537 ∈ wcel 2114 ≠ wne 3016 ∩ cin 3935 ∅c0 4291 {csn 4567 |
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-10 2145 ax-11 2161 ax-12 2177 ax-ext 2793 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-tru 1540 df-ex 1781 df-nf 1785 df-sb 2070 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-ne 3017 df-ral 3143 df-v 3496 df-dif 3939 df-in 3943 df-nul 4292 df-sn 4568 |
This theorem is referenced by: disjpr2 4649 disjtpsn 4651 difprsn1 4733 otsndisj 5409 xpsndisj 6020 funprg 6408 funtp 6411 funcnvpr 6416 f1oprg 6659 xp01disjl 8121 enpr2d 8597 phplem1 8696 djuin 9347 pm54.43 9429 pr2nelem 9430 f1oun2prg 14279 s3sndisj 14327 sumpr 15103 cshwsdisj 16432 setsfun0 16519 setscom 16527 gsumpr 19075 dmdprdpr 19171 dprdpr 19172 ablfac1eulem 19194 cnfldfun 20557 m2detleib 21240 dishaus 21990 dissnlocfin 22137 xpstopnlem1 22417 perfectlem2 25806 cosnopne 30430 prodpr 30542 esumpr 31325 esum2dlem 31351 prodfzo03 31874 onint1 33797 bj-disjsn01 34267 lindsadd 34900 poimirlem26 34933 sumpair 41341 perfectALTVlem2 43936 |
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