Can conditional muaj counterexample?

Cov txheej txheem:

Can conditional muaj counterexample?
Can conditional muaj counterexample?
Anonim

Rau ib nqe lus raws li kev cai (yog-thaum) tus piv txwv yuav tsum yog ib qho piv txwv uas txaus siab rau qhov kev xav, tab sis tsis yog qhov xaus.

Yuav ua li cas yog qhov piv txwv rau qhov chaw muaj cai?

Counterexample: ib qho piv txwv uas cuam tshuam qee nqe lus lossis kev sib cav (ex. … Invalid: ib qho kev sib cav uas tsis siv tau. muaj tseeb thiab pom seb puas tseem ua tau rau qhov kev txiav txim tsis tseeb. Yog tias qhov no ua tau, qhov kev sib cav tsis raug.

Cov nqe lus muaj cai tuaj yeem yog cuav?

Ib qho xwm txheej raug suav hais tias yog qhov tsis tseeb thaum qhov tseeb yog qhov tseeb thiab qhov tshwm sim yog cuav. Hauv qab no, qhov tseeb qhov tseem ceeb ntawm cov xwm txheej rau txhua qhov muaj peev xwm ntawm qhov ua ntej thiab qhov tshwm sim yog qhov tseeb lossis qhov tsis tseeb yog sawv cev hauv lub rooj qhov tseeb.

Ib qho piv txwv ntawm tus piv txwv yog dab tsi?

Ib qho piv txwv uas tsis lees paub ib nqe lus (qhia tias nws yog cuav). Piv txwv li: nqe lus " txhua tus dev muaj plaub hau " tuaj yeem ua pov thawj cuav los ntawm kev nrhiav ib tus dev tsis muaj plaub hau (tus piv txwv) zoo li hauv qab no.

Yuav ua li cas muaj pes tsawg tus piv txwv los qhia tias cov lus hais tsis raug?

Nws tsuas yog siv ib qho piv txwv qhia tias koj cov lus tsis tseeb.

Pom zoo:

Nthuav cov khoom
Puas yog homomorphism tib yam li isomorphism?
Nyeem ntxiv

Puas yog homomorphism tib yam li isomorphism?

Isomorphism yog homomorphism tshwj xeeb. Greek keeb kwm "homo" thiab "morph" ua ke txhais tau tias "zoo tib yam." Muaj ob qhov xwm txheej uas homomorphisms tshwm sim: thaum ib pab pawg yog ib pawg ntawm lwm pawg;

Yuav tau sawv los yog tshwm sim?
Nyeem ntxiv

Yuav tau sawv los yog tshwm sim?

Peb hom tshwm sim yog arise, sawv, arisen. Nws yog siv hauv cov ntsiab lus tseem ceeb: Ib lub sijhawm tshwm sim thiab nws txiav txim siab los ua txoj haujlwm hauv Brussels. Ib qho teeb meem tshwm sim nrog kuv daim ntawv hla tebchaws. Koj siv arose hauv kab lus li cas?

Nyob hauv qab ceg cov leeg nqaij gastrocnemius khoov?
Nyeem ntxiv

Nyob hauv qab ceg cov leeg nqaij gastrocnemius khoov?

Cov leeg nqaij gastrocnemius flexes ko taw ntawm pob qij txha- uas yog nws ua rau taw taw ko taw nqes los ntawm khoov nws ntawm pob taws pob taws, xws li thaum koj sawv ntawm koj. cov ntiv taw. Qhov kev txiav txim no hu ua plantar flexion. Lub gastrocnemius kuj flexes ceg ntawm lub hauv caug sib koom.