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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 4544 | . . . 4 ⊢ (𝐵 ∈ {𝐴} → 𝐵 = 𝐴) | |
2 | 1 | eqcomd 2742 | . . 3 ⊢ (𝐵 ∈ {𝐴} → 𝐴 = 𝐵) |
3 | 2 | necon3ai 2957 | . 2 ⊢ (𝐴 ≠ 𝐵 → ¬ 𝐵 ∈ {𝐴}) |
4 | disjsn 4613 | . 2 ⊢ (({𝐴} ∩ {𝐵}) = ∅ ↔ ¬ 𝐵 ∈ {𝐴}) | |
5 | 3, 4 | sylibr 237 | 1 ⊢ (𝐴 ≠ 𝐵 → ({𝐴} ∩ {𝐵}) = ∅) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 = wceq 1543 ∈ wcel 2112 ≠ wne 2932 ∩ cin 3852 ∅c0 4223 {csn 4527 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1803 ax-4 1817 ax-5 1918 ax-6 1976 ax-7 2018 ax-8 2114 ax-9 2122 ax-ext 2708 |
This theorem depends on definitions: df-bi 210 df-an 400 df-tru 1546 df-fal 1556 df-ex 1788 df-sb 2073 df-clab 2715 df-cleq 2728 df-clel 2809 df-ne 2933 df-ral 3056 df-v 3400 df-dif 3856 df-in 3860 df-nul 4224 df-sn 4528 |
This theorem is referenced by: disjpr2 4615 disjtpsn 4617 difprsn1 4699 otsndisj 5387 xpsndisj 6006 funprg 6412 funtp 6415 funcnvpr 6420 f1oprg 6683 xp01disjl 8201 enpr2d 8703 phplem1 8803 djuin 9499 pm54.43 9582 pr2nelem 9583 f1oun2prg 14447 s3sndisj 14495 sumpr 15275 cshwsdisj 16615 setsfun0 16701 setscom 16709 gsumpr 19294 dmdprdpr 19390 dprdpr 19391 ablfac1eulem 19413 cnfldfun 20329 m2detleib 21482 dishaus 22233 dissnlocfin 22380 xpstopnlem1 22660 perfectlem2 26065 cosnopne 30701 prodpr 30814 esumpr 31700 esum2dlem 31726 prodfzo03 32249 onint1 34324 bj-disjsn01 34828 lindsadd 35456 poimirlem26 35489 sumpair 42192 perfectALTVlem2 44790 |
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