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求道九州 永远永远酱w 1337 字 2022-10-20

(AcardinalκisaBerkeleycardinal,ifforanytransitivesetMwithκ∈Mandanyordinalα<κthereisanelementaryembeddingj:MMwithα<critj<κ.ThesecardinalsaredefinedinthecontextofZFsettheorywithouttheaxiomofchoice.TheBerkeleycardinalsweredefinedbyW.HughWoodininabout1992athisset-theoryseminarinBerkeley,withJ.D.Hamkins,A.Lewis,D.Seabold,G.HjorthandperhapsR.Solovayintheaudience,amongothers,issuedasachallengetorefuteaseeminglyover-stronglargecardinalaxiom.Nevertheless,theexistenceofthesecardinalsremainsunrefutedinZF.IfthereisaBerkeleycardinal,thenthereisaforcingextensionthatforcesthattheleastBerkeleycardinalhascofinalityω.ItseemsthatvariousstrengtheningsoftheBerkeleypropertycanbeobtainedbyimposingconditionsonthecofinalityofκ(Thelargercofinality,thestrongertheoryisbelievedtobe,uptoregularκ).IfκisBerkeleyanda,κ∈MforMtransitive,thenforanyα<κ,thereisaj:MMwithα<critj<κandj(a)=a.Acardinalκiscalledproto-BerkeleyifforanytransitiveMκ,thereissomej:MMwithcritj<κ.Moregenerally,acardinalisα-proto-BerkeleyifandonlyifforanytransitivesetMκ,thereissomej:MMwithα<critj<κ,sothatifδ≥κ,δisalsoα-proto-Berkeley.Theleastα-proto-Berkeleycardinaliscalledδα.WecallκaclubBerkeleycardinalifκisregularandforallclubsCκandalltransitivesetsMwithκ∈Mthereisj∈E(M)withcrit(j)∈C.WecallκalimitclubBerkeleycardinalifitisaclubBerkeleycardinalandalimitofBerkeleycardinals.RelationsIfκistheleastBerkeleycardinal,thenthereisγ<κsuchthat(Vγ,Vγ+1)ZF2+“ThereisaReinhardtcardinalwitnessedbyjandanω-hugeaboveκω(j)”(Vγ,Vγ+1)ZF2+“ThereisaReinhardtcardinalwitnessedbyjandanω-hugeaboveκω(j)”.Foreveryα,δαisBerkeley.ThereforeδαistheleastBerkeleycardinalaboveα.Inparticular,theleastproto-Berkeleycardinalδ0isalsotheleastBerkeleycardinal.IfκisalimitofBerkeleycardinals,thenκisnotamongtheδα.EachclubBerkeleycardinalistotallyReinhardt.TherelationbetweenBerkeleycardinalsandclubBerkeleycardinalsisunknown.IfκisalimitclubBerkeleycardinal,then(Vκ,Vκ+1)“ThereisaBerkeleycardinalthatissuperReinhardt”.Moreover,theclassofsuchcardinalsarestationary.ThestructureofL(Vδ+1)IfδisasingularBerkeleycardinal,DC(cf(δ)+),andδisalimitofcardinalsthemselveslimitsofextendiblecardinals,thenthestructureofL(Vδ+1)issimilartothestructureofL(Vλ+1)undertheassumptionλi.e.thereissomej:L(Vλ+1)L(Vλ+1).Forexample,Θ=ΘL(Vδ+1)Vδ+1,thenΘisastronglimitinL(Vδ+1),δ+isregularandmeasurableinL(Vδ+1),andΘisalimitofmeasurablecardinals. , )

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