Is it possible to derive the rules of set theory as transfers from the pure finite set world, and can we extend this further?

Is it possible to derive the rules of set theory as transfers from the pure finite set world, and can we extend this further?

InformallytheideaofthisquestionisaboutwhethertherulesofsettheorycanbederivedasatransferofsomerulesfromthehereditarilyfinitesetrealmandwhetherthistransferprincipleitselfcanbecoinedfornotionsotherthanthefinitenotionTheprincipleIwanttonegotiateisifphiisapropertythatisdefinablebyaformulainthelanguageofsettheorythatisstrictlyshorterthantheshortestparameterfreeformulainthatlanguagethatcandefinefinitenessthenifphiisCLOSEDonthethehereditarilyfinitesetworldthenitcanbegeneralizedoverthewholerealmofsetsThecrudeinformalideaisthatifapropertythatcannotmentionfinitenessgeneralizesoverthewholehereditarilyfinitesetrealmthenitcangobeyonditToformallycapturethatIllworkupinaclasstheorysowedefinesetasanelementofaclassthelanguageofthetheoryismonosortedfirstorderlogicwithidentityandmembershipwestipulateaxiomsofExtensionalityasinZFClasscomprehensionschemaforallx1xnexistsxxysetywedgephiyx1xnTheemptyclassisasetSingletonsforallxsetxtosetxBooleanUnionforallxysetxwedgesetytosetxcupyDefinefinAiffforallKforallxxinAtoexistsyyinKwedgexinywedgeforallzzinytozxwedgeforallabainKwedgebinKtoexistsccinKwedgeforallddincleftrightarrowdinalordinbtoAinKInEnglishAisfiniteifandonlyifitisanelementofeveryclassKthatisclosedunderBooleanunionandthathasthesingletonsofallelementsofAamongitselementsIthinkthisisalongtheshortestwaytodefinefinitesetinthefirstorderlanguageofsettheoryPerhapstheaboveformulacanbeshortenedfurtherorperhapsthereisanothershorterparameterfreeformulationofxisafinitesetinthelanguageofsettheoryhoweverforthesakeofpresentationherewelltakethisformulatobetheshortestformuladefiningfinitenessforallxxtextishereditarilyfinitetosetxWherexishereditarilyfiniteisdefinedasthetransitiveclosureclassofxbeingfiniteWeshalldenotetheclassofallsetsbyVandtheclassofallhereditarilyfintiesetsbyHFHFinVTheprincipleofTransferfromthepurefiniteworldifphiyxisaformulashorterthananyformuladefiningfinitenessinwhichonlysymbolsyxoccurfreeandthoseonlyoccurfreethenforallxxinHFtoforallyphiyxtoyinHFtoforallxinVforallyphiyxtoyinVNowitisclearthatallaxiomsofUnionPowerandSeparationoversetsarederivablefromtheabovetransferprincipleandsoZCisinterpretablehereActaullyifwerestrictphitohavenomorethanthreeatomicsubformulaswecanstillinterpretthewholeofZCReplacementisnotinterpretablebythisprincipleYetaminormodificationofthisprinciplemightsucceedinprovingreplacementoversetsthiscanbedonebychangingtheclosurepropertytoinvolveonlysubsetsofHFwhatIcallasproximityclosureoverHFsotorestatethat8TheprincipleofTransferfromproximityofthepurefiniteworldifphiyxisaformulashorterthananyformuladefiningfinitenessinwhichonlysymbolsyxoccurfreeandthoseonlyoccurfreethenforallxxinHFtoforallysubseteqHFphiyxtoyinHFtoforallxinVforallyphiyxtoyinVThatreplacementisprovablecanbeshownfromexaminingthefollowingformulawhoselengthisshorterthananyformuladefiningfinitenessexistsFforallmminFtoexistsabainAwedgebinBwedgeainmwedgebinmwedgeforallmnminFwedgeninFwedgeexistskkinmwedgekinntonmNowifAishereditarilyfiniteandBisasubsetofHFthatfulfillstheaboveformulathenBishereditarilyfinitethismeanthatthepropertydefinedbytheaboveformulaisproximityclosedoverthehereditarilyfiniteworldIdonthaveanyproofofconsistencyoftheseprinciplesbutifthereisnoclearinconsistencyofthoserelativetoZForMKorsomeextensionofthosethencoulditbepossibletothinkofextendingthatprincipletopropertiesotherthanxisfinitesowegeneralizeittosomelinepropertiessoforapropertyPinthatlinewestipulatethatanypredicateQthatisclosedoverthepurePworldwouldgeneralizeoverthewholesetworldorevenstrongeranypredicateQthatisproximityclosedoverthepurePworldwouldgeneralizeoverthewholesetworldOfcourseinbothcasesQmustbeexpressiblebyaformulastrictlyshorterthantheshortestexpressiondefiningpropertyPandalsowestipulateparallelaxiomssufficienttodefinethepropertyPalsoaxiomsassertingtheelementhoodofallhereditarilyPclassesandtheexistenceofasetofallhereditarilyPsetsOfcoursethiscanonlybedoneforsomeselectedlineofpropertiesisthatpossibleoritisinvolvedwithclearinconsistenciesandwhatwouldbethegeneralqualificationofsuchpropertyP

Комментарии

Популярные сообщения из этого блога

Skipping acquire of configured file 'contrib/binary-i386/Packages' as repository … doesn't support architecture 'i386'

Connection string for MariaDB using ODBC

Celery like system based on django channels