A CHARACTERIZATION OF QUANTIC QUANTIFIERS IN ORTHOMODULAR LATTICES
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TheoryandApplicationsofCategories,Vol.16,No.10,2006,pp.206–217.
ACHARACTERIZATIONOFQUANTICQUANTIFIERSIN
ORTHOMODULARLATTICES
DedicatedtoProfessorHumbertoC´ardenason
theoccasionofhis80thBirthday
LEOPOLDOROM´AN
Abstract.LetLbeanarbitraryorthomodularlattice.Thereisaonetoonecor-respondencebetweenorthomodularsublatticesofLsatisfyinganextraconditionandquanticquantifiers.Thecategoryoforthomodularlatticesisequivalenttothecategoryofposetshavingtwofamiliesofendofunctorssatisfyingsixconditions.
Introduction
Thepurposeofthispaperistogivesomenewresultsconcerningquanticquantifierson
orthomodularlattices.Asiswellknown,quantifiershavetheirmainsourceinthetheory
ofAlgebraicLogicandinthetheoryoforthomodularlattices.Morerecently,quantifiers
becameimportantinthetheoryofidempotent,right-sidedquantales.
Insection1wedealwiththenotionofaquanticquantifierandcharacterizesuch
quanticquantifiersinorthomodularlattices.
Insection2weapplytheresultsofsection1forthealgebraicfoundationsofquantum
mechanics.Wealsoshowthefollowing:thecategoryoforthomodularlatticesisequivalent
tothecategoryofposetshavingtwofamiliesofendofunctorssatisfyingsomeconditions.
PartofthisworkwasdonewhentheauthorwasaresearchvisitoratLouisianaTech
University.ManythankstoProf.R.Greechieforhisinvitationandmanyconversations.
AlsomanythankstoProf.M.F.Janowitzfortheelectronicmailshesentmeandthe
commentshemadeaboutquantifiers.ThisworkwaspartiallysupportedbyaBeca
Sab´aticadelaDGAPAdelaUNAM.
1.QuanticQuantifiers
Theclassicnotionofaquantifierwasintroducedin[6]whereP.Halmosgaveachar-
acterizationofquantifiersforBooleanAlgebras.Latter,M.F.Janowitzgeneralizedthis
conceptfororthomodularlattices,see[7]fordetails.Thereisanotherconcept,namely,
Receivedbytheeditors2005-12-15and,inrevisedform,2006-03-23.TransmittedbyF.W.Lawvere.Publishedon2006-04-15.2000MathematicsSubjectClassification:03G12;06C99.Keywordsandphrases:Quantumlogic;Orthomodularlattice.cLeopoldoRom´an,2006.Permissiontocopyforprivateusegranted.
206ACHARACTERIZATIONOFQUANTICQUANTIFIERS207
thenotionofanucleusforHeytingAlgebras.Nucleiandquantifiershaveacloserelation
asweshallsee.
1.1.Definition.AboundedlatticeL=(L,∨,∧,0,1)isanortholatticeifthereexistsa
unaryoperation⊥:L→Lsatisfyingtheconditions:
1.a⊥⊥=a.
2.a,b∈L:(a∨b)⊥=a⊥∧b⊥.
3.a∨a⊥=1.
4.a∧a⊥=0.
a,bbeingarbitraryelementsofL.
IfLisanortholattice,weshallsayLisanorthomodularlatticeifitsatisfiesthe
followingweakmodularityproperty:
Givenanya,b∈Lwitha≤bwehave:b=a∨(a⊥∧b)(equivalently,a=(a∨b⊥)∧b).
IfLandMareorthomodularlattices,afunctionf:L→Missaidtobeamorphism
oforthomodularlatticesiffthefollowingpropertieshold:
1.f(1)=1.
2.f(a∧b)=f(a)∧f(b),foralla,b∈L.
3.f(a⊥)=f(a)⊥,foralla∈L.
Thecompositionofmorphismsisdefinedintheusualwayandclearly,wehavea
category,denotedbyOML.
IfLisaboundedlatticewithbounds0,1andF:L→Lisafunction,Fwillbecalled
aquantifieronLincaseFsatisfies:
1.F(0)=0.
2.Foranya∈L,a≤F(a).
3.F(a∧F(b))=F(a)∧F(b),foralla,b∈L.
IfwewriteF(a∧b)=F(a)∧F(b)in3andwedonotassumecondition1thenweget
thenotionofanucleus.ThetheoryofnucleiisgiveninthecontextofHeytingAlgebras
orLocales,thereadercansee[8]wherethereisastudyofnucleiforHeytingAlgebras.In
[11]theauthorandBeatrizRumbosgaveacharacterizationofnucleiandquanticnuclei
fororthomodularlattices.
TherearealwaystwospecialquantifiersonL:208LEOPOLDOROM´AN
1.Thediscretequantifier=theidentitymap.
2.Theindiscretequantifierquantifier:F(a)=1fora=0,F(0)=0.
Everynucleusisaquantifierbutnotconversely.Ifwetaketheindiscretequantifier
itisnothardtoshowthatitisnotanucleuswheneverLisaHeytingalgebraoran
orthomodularlattice.
Now,forthenotionofaquanticquantifierweneedtointroduceabinaryconnective
&foranarbitraryorthomodularlattice.
1.2.Definition.LetLbeanorthomodularlattice,wedefinetwobinaryoperationsas
follows:Ifa,barearbitraryelementsofL
1.a&b=(a∨b⊥)∧b.
2.a→b=a⊥∨(a∧b).
Itisnothardtoshowthefollowing:
a&b≤ciffa≤b→c.
Thelastclaimhastwoequivalentmeanings.Wecansay,thefunction:F(−b):L→L
givenby:F(−,b)(a)=a&bisaresiduatedmaporthefunctorF(−,b):L→Lgiven
bythesamerulehasarightadjoint.So,isjustaquestionofterminology;theimportant
ideahereisthelastinequalityandtheconnective&.Toourknowledge,P.D.Finchwas
thefirstpersontoconsider&asabinaryconnective.See[5]formoredetails.Also,the
readercanconsult[2]foradetailedaccountofResiduationTheory.
Wejustfinishwithanothercomment:F(−,b)iscalledtheSasakiprojectionandthe
rightadjointH(b,−)isknowninphysicsastheSasakihook;butremember,weshall
viewthisprojectionasabinaryconnective,replacingtheclassicalconnective∧.Fora
HeytingalgebraA,itiswellknownthefunctora∧−:A→A,hasarightadjoint.In
fact,wheneverAisabooleanalgebratherightadjointisgivenby:a→b=a⊥∨b.,a,b
areelementsofA.
Fororthomodularlattices,thesituationisquitedifferent.Indeed,onemightaskif
theclassicalconnectivehasarightadjoint:Whenthispropertyissatisfied,thenLisa