Bertrand Model Tsim thiab nta

Kev sib tw yog lub hauv paus ntawm kev ua lag luam khwv nyiaj txiag qauv. Nws yog nyob rau no hauv paus yog tsim los pab cov thiaj li hu ua equilibrium nqi uas satisfies ob tau txais kev pab thiab buyers. Bertrand qauv qhia txog qhov no yuav tsum muaj tshwm sim ntawm cov kev ua lag luam khwv nyiaj txiag. Nws twb formulated nyob rau hauv 1883 nyob rau hauv txoj kev ntsuam xyuas ntawm phau ntawv "lej hauv paus ntsiab lus ntawm cov kev tshawb xav ntawm wealth." Qhov kawg sau piav txog tus Cournot qauv. Bertrand kuv tsis pom zoo nrog rau cov lus xaus ntawm kws tshawb fawb. Cov kev ntsuam xyuas, nws formulated ib tug qauv, tab sis nws yog lej piav Frensis Edzhuort xwb nyob rau hauv 1889.

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Bertrand qauv qhia txog ib tug teeb meem ntawm oligopoly. muaj tsawg kawg yog ob tug tuam txhab uas muag nyob rau hauv cov lag luam uas tsim homogeneous khoom. Lawv yuav tsis pa roj carbon monoxide-ua hauj lwm. Npe sib tw nrog txhua lwm yam los ntawm qhov chaw kawm tus nqi rau lawv cov khoom. Txij li thaum cov khoom no yog homogeneous, qhov kev thov rau cheaper cov khoom tam sim ntawd yuav siv sij hawm tawm. Yog hais tias ob qho tag nrho lub npe teev tus nqi qub, nws yog muab faib ua ob sib npaug zos qhov chaw. Bertrand qauv yog tsis tsuas haum rau qhov teeb meem ntawm ib tug duopoly, tab sis thaum ntxhab nyob rau hauv kev ua lag luam ntau ntau yam. Txawm li cas los, lub ntsiab assumption yog lub homogeneity ntawm lawv cov khoom. Nws tseem yog ib qho tseem ceeb uas technology tuam txhab uas muag yog tsis sib txawv. Qhov no txhais tau tias lawv marginal thiab nruab nrab nqi yog zoo tib yam thiab yog competitively luv nqi. Kom ntau lawm npe yuav endlessly. Nws yog pom tseeb tias lawv yuav ua li cas thiaj li ntev raws li tus nqi ntawm lub lag luam npog lawv cov nqi. Yog hais tias nws yog qhov tsawg, cov ntau lawm tsis ua rau kev txiav txim zoo. Tsis muaj ib tug yuav ua hauj lwm ntawm ib tug tsis tau.

Bertrand Model Tsim thiab nta

Tab sis dab tsi yog qhov zoo nyob rau hauv cov ntaub ntawv twg rau lub tuam txhab yuav xaiv? Nws nkawd hais tias tag nrho cov manufacturers yuav tau txais txiaj ntsim, yog hais tias txhua yam uas lawv yuav teem siab nqi. Txawm li cas los, Bertrand qauv qhia tau hais tias nyob rau hauv ib qhov teeb meem nyob qhov twg npe tsis koom tes nrog txhua lwm yam, nws yuav tsis tshwm sim. Sis tw nqi yog sib npaug zos rau marginal nqi, nyob rau hauv raws li cov Nash equilibrium. Tab sis yog vim li cas yog no mas? Tseeb, nyob rau hauv cov ntaub ntawv no, ib tug yuav tsis ua ib cov nyiaj?

Piv txwv hais tias ib tug tuam txhab teev ib tug nqi uas yog ntau tshaj nws marginal nqi, thiab lub thib ob - tsis muaj. Nws tsis yog nyuaj rau twv seb dab tsi yuav tshwm sim nyob rau hauv cov ntaub ntawv no. Tag nrho cov tub lag luam yuav opt rau cov khoom ntawm lub thib ob ruaj. Bertrand qauv, cov tej yam kev mob muaj xws li hais tias tus tom kawg yuav muaj peev xwm ua ntau lawm indefinitely.

Piv txwv hais tias ob lub npe teev tus nqi qub, uas yog siab tshaj lawv marginal nqi. Qhov no yog ib tug heev tsis ruaj tsis khov teeb meem no. Txhua lub tuam txhab uas muag yuav nrhiav coj tus nqi mus coj dua lub lag luam. Yog li ntawd nws yuav muaj peev xwm ua nws profit yuav luag ob npaug. Tsis ruaj khov equilibrium nyob rau hauv ib qhov teeb meem nyob qhov twg ob leeg npe teev txawv tus nqi uas muaj ntau tshaj li marginal nqi. Tag nrho cov tub lag luam mus rau qhov chaw uas cov khoom cheaper. Yog li ntawd, tsuas tau equilibrium yog ib qhov teeb meem nyob qhov twg ob leeg npe teev nqi hais tias yog sib npaug zos rau cov marginal nqi.

Cournot qauv

Tus neeg sau ntawm "zauv hauv paus ntsiab lus ntawm cov kev tshawb xav ntawm wealth," ntseeg hais tias tus nqi yog yeej ib txwm siab tshaj lub marginal nqi ntawm manufactured khoom, vim hais tias cov tuam txab lawv tus kheej xaiv tus nqi ntawm lawv cov teeb meem. Bertrand qauv qha tau tias nws tsis yog. Txawm li cas los, tag nrho cov kev xav uas nws yuav siv tau formulated Cournot. Cov lawv:

• Nyob rau hauv kev ua lag luam rau ntau tshaj ib tug ruaj. Txawm li cas los, cov khoom uas hais tias lawv tsim yog homogeneous.
• Npe tsis tau los yog tsis xav kom muab kev koom tes.
• Cov tshuaj ntawm txhua tus ntawm cov tuam txhab uas muag nyob rau hauv qhov teeb meem ntawm lub Scope ntawm tej yam nyob rau hauv lub tsim los pab rau tus nqi lag luam ntawm cov khoom.
• Manufacturers ua rationally thiab xav hais tias leeg, nrhiav kom maximize lawv profits.

Piv qauv

Bertrand kev sib tw yog kom txo tau cov nqi, Cournot - maximize tso zis. Tab sis uas qauv yog ntau tseeb? Bertrand hais tias lub tej yam kev mob ntawm duopoly npe yuav raug yuam kom muab tus nqi ntawm ib theem ntawm lawv marginal nqi. Yog li ntawd, nyob rau hauv lub kawg, txhua yam yuav raug txo kom meej kev sib tw. Txawm li cas los, nyob rau hauv kev xyaum nws hloov tawm hais tias tsis yog txhua txhua lub sectors li yooj yim yuav hloov qhov ntim ntawm lub qhov teeb meem, raws li Bertrand. Nyob rau hauv cov ntaub ntawv no, zoo dua qhia txog cov teeb meem Cournot qauv. neb ob leeg yuav tsum tau siv nyob rau hauv tej rooj plaub. Nyob rau hauv thawj theem, npe xaiv cov qhov tso zis tagnrho, lub thib ob - sib tw nyob rau hauv Bertrand qauv, qhov chaw tus nqi. Nyias, peb yuav tsum xav txog cov ntaub ntawv nyob qhov twg lub xov tooj ntawm tuam txab nyob rau hauv kev ua lag luam nyhav infinity. Ces tus Cournot qauv qhia tau hais tias tus nqi yog sib npaug zos rau marginal nqi. Yog li, nyob rau hauv cov tej yam kev mob, tag nrho cov kev khiav hauj lwm nyob rau hauv raws li cov lus xaus ntawm Bertrand.

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Bertrand qauv siv cov kev xav uas yog heev deb ntawm lub neej tiag tiag. Piv txwv li, nws yog Kwv yees hais tias shoppers yuav mus yuav qhov pheej yig tshaj cov khoom. Txawm li cas los, nyob rau hauv kev muaj tiag lub lag luam yog tsis nqi sib txeeb. Cov khoom uas yog txawv, tsis homogeneous. Muaj kuj yog ib tug thauj cov nqi. Tsis muaj leej twg xav mus ob zaug kom deb li deb mus yuav khoom pheej yig dua los ntawm 1%, yog hais tias nws yuav siv rau qhov no yog ntau tshaj li 1% ntawm tus nqi. To taub nws thiab cov producers. Yog li ntawd, nyob rau hauv lub neej tiag tiag, Bertrand qauv feem ntau tsis ua hauj lwm.

Ib qho tseem ceeb sib txawv yog hais tias tsis muaj lub tuam txhab yuav nyob rau hauv kev xyaum tsis txhob ua rau kom lub peev xwm ntau indefinitely. Nws sau tseg ntxiv Edgeworth. Nqi nyob rau hauv lub neej tiag tiag tsis sib haum mus rau lub marginal nqi producers. Qhov no yog vim lub fact tias cov kev xaiv ntawm lub tswv yim yog tsis yooj yim li, raws li cov Nash equilibrium.

nyob rau hauv kev xyaum

Bertrand qauv qhia tau hais tias oligopoly yog ib nrab theem. Yog hais tias tuam txab yuav tsis pom zoo thiab tsis kam muab kev koom tes rau lawv cov kev siv zog, lawv yuav muag lawv cov khoom ntawm cov nqi sib npaug zos rau marginal nqi. Tsis muaj ib tug yuav poob, tab sis yuav tsis tau txais cov nyiaj tau. Zoo qhov teeb meem no zoo li nyob rau hauv xyaum. Ob peb lub npe ua zoo xws li cov, yog ib qho yooj yim txaus. Qhov no yog txawm ntau heev rau tag nrho cov. Nyob rau hauv cov ntaub ntawv no, tus nqi lag luam yog teem sib npaug zos rau cov monopoly. Txhua lub tuam txab ua khoom nyob rau hauv lub Scope ntawm nws cov nta. Qhov kom zoo dua ntawm lub neej tiag tiag tuam txab yuav tau tsuas yog los ntawm cov tshiab technologies.