A set A yog subset ntawm lwm txheej B yog tias tag nrho cov ntsiab lus ntawm cov teeb A yog cov ntsiab lus ntawm cov teeb B. Hauv lwm lo lus, cov teeb A muaj nyob hauv cov teeb B. Qhov kev sib raug zoo ntawm cov subset yog suav tias yog A⊂B. … Txij li thaum B muaj cov ntsiab lus tsis nyob hauv A, peb tuaj yeem hais tias A yog qhov tsim nyog ntawm B.
Yuav ua li cas koj pom lub subset ntawm ib lub teeb?
Yog tias ib lub teeb muaj "n" cov ntsiab lus, ces tus lej ntawm cov txheej txheem muab yog 2 thiab tus naj npawb ntawm cov subsets tsim nyog ntawm qhov muab subset yog muab los ntawm2 -1. Xav txog ib qho piv txwv, Yog tias teeb A muaj cov ntsiab lus, A={a, b}, ces qhov tsim nyog subset ntawm qhov muab subset yog { }, {a}, thiab {b}.
Dab tsi yog subsets ntawm tag nrho cov teeb?
Txhua qhov teeb tsa yog suav tias yog ib qho ntawm nws tus kheej. Tsis muaj teeb meem yog qhov tsim nyog subset ntawm nws tus kheej. Lub khoob khoob yog subset ntawm txhua lub teeb. Cov khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob.
Dab tsi yog qhov subset ntawm A={ 1 2 3 }?
Teb: Lub teeb {1, 2, 3} muaj 8 subsets.
piv txwv ntawm subset yog dab tsi?
A teeb A yog ib qho subset ntawm lwm cov teeb B yog tias tag nrho cov ntsiab lus ntawm teeb A yog cov ntsiab lus ntawm teeb B. Hauv lwm lo lus, cov teeb A yog muaj nyob rau hauv cov teeb B. Cov kev sib raug zoo sib txuas yog qhia tias yog A ⊂B. Piv txwv li, yog A yog tus set {♢, ♡, ♣, ♠} thiab B yog txheej {♢, △, ♡, ♣, ♠}, ces A⊂B tab sis B⊄A
