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.c󰀐LeopoldoRom´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