伯克利
AcardinalκisaBerkeleycardinal,ifforanytransitivesetMwithκ∈Mandanyordinalα<κthereisanelementaryembeddingj:M≺Mwithα<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:M≺Mwithα<critj<κandj(a)=a
Acardinalκiscalledproto-BerkeleyifforanytransitiveM∋κ,thereissomej:M≺Mwithcritj<κ.Moregenerally,acardinalisα-proto-BerkeleyifandonlyifforanytransitivesetM∋κ,thereissomej:M≺Mwithα<critj<κ,sothatifδ≥κ,δisalsoα-proto-Berkeley.Theleastα-proto-Berkeleycardinaliscalledδα
WecallκaclubBerkeleycardinalifκisregularandforallclubsC⊆κandalltransitivesetsMwithκ∈Mthereisj∈E(M)withcrit(j)∈C
WecallκalimitclubBerkeleycardinalifitisaclubBerkeleycardinalandalimitofBerkeleycardinals
Relations
IfκistheleastBerkeleycardinal,thenthereisγ<κsuchthat(Vγ,Vγ+1)⊨ZF2+“ThereisaReinhardtcardinalwitnessedbyjandanω-hugeaboveκω(j)”(Vγ,Vγ+1)⊨ZF2+“ThereisaReinhardtcardinalwitnessedbyjandanω-hugeaboveκω(j)”
Foreveryα,δαisBerkeley.ThereforeδαistheleastBerkeleycardinalaboveα
Inparticular,theleastproto-Berkeleycardinalδ0isalsotheleastBerkeleycardinal
IfκisalimitofBerkeleycardinals,thenκisnotamongtheδα
EachclubBerkeleycardinalistotallyReinhard
TherelationbetweenBerkeleycardinalsandclubBerkeleycardinalsisunknown
IfκisalimitclubBerkeleycardinal,then(Vκ,Vκ+1)⊨“ThereisaBerkeleycardinalthatissuperReinhardt”.Moreover,theclassofsuchcardinalsarestationary
ThestructureofL(Vδ+1)
IfδisasingularBerkeleycardinal,DC(cf(δ)+),andδisalimitofcardinalsthemselveslimitsofextendiblecardinals,thenthestructureofL(Vδ+1)issimilartothestructureofL(Vλ+1)undertheassumptionλisI0;i.e.thereissomej:L(Vλ+1)≺L(Vλ+1).Forexample,Θ=ΘL(Vδ+1)Vδ+1,thenΘisastronglimitinL(Vδ+1),δ+isregularandmeasurableinL(Vδ+1),andΘisalimitofmeasurablecardinals
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:M≺Mwithα<critj<κandj(a)=a
Acardinalκiscalledproto-BerkeleyifforanytransitiveM∋κ,thereissomej:M≺Mwithcritj<κ.Moregenerally,acardinalisα-proto-BerkeleyifandonlyifforanytransitivesetM∋κ,thereissomej:M≺Mwithα<critj<κ,sothatifδ≥κ,δisalsoα-proto-Berkeley.Theleastα-proto-Berkeleycardinaliscalledδα
WecallκaclubBerkeleycardinalifκisregularandforallclubsC⊆κandalltransitivesetsMwithκ∈Mthereisj∈E(M)withcrit(j)∈C
WecallκalimitclubBerkeleycardinalifitisaclubBerkeleycardinalandalimitofBerkeleycardinals
Relations
IfκistheleastBerkeleycardinal,thenthereisγ<κsuchthat(Vγ,Vγ+1)⊨ZF2+“ThereisaReinhardtcardinalwitnessedbyjandanω-hugeaboveκω(j)”(Vγ,Vγ+1)⊨ZF2+“ThereisaReinhardtcardinalwitnessedbyjandanω-hugeaboveκω(j)”
Foreveryα,δαisBerkeley.ThereforeδαistheleastBerkeleycardinalaboveα
Inparticular,theleastproto-Berkeleycardinalδ0isalsotheleastBerkeleycardinal
IfκisalimitofBerkeleycardinals,thenκisnotamongtheδα
EachclubBerkeleycardinalistotallyReinhard
TherelationbetweenBerkeleycardinalsandclubBerkeleycardinalsisunknown
IfκisalimitclubBerkeleycardinal,then(Vκ,Vκ+1)⊨“ThereisaBerkeleycardinalthatissuperReinhardt”.Moreover,theclassofsuchcardinalsarestationary
ThestructureofL(Vδ+1)
IfδisasingularBerkeleycardinal,DC(cf(δ)+),andδisalimitofcardinalsthemselveslimitsofextendiblecardinals,thenthestructureofL(Vδ+1)issimilartothestructureofL(Vλ+1)undertheassumptionλisI0;i.e.thereissomej:L(Vλ+1)≺L(Vλ+1).Forexample,Θ=ΘL(Vδ+1)Vδ+1,thenΘisastronglimitinL(Vδ+1),δ+isregularandmeasurableinL(Vδ+1),andΘisalimitofmeasurablecardinals
温馨提示:按 回车[Enter]键 返回书目,按 ←键 返回上一页, 按 →键 进入下一页,加入书签方便您下次继续阅读。