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我最近开始使用SPARQL和一些练习来进行SPARQL查询，这将使我能够从下面的.ttl文件中获取数据。
我在以下问题上遇到困难：
未解决
获得所有参加过披头四乐队披头四首歌曲的音乐家的名字（不包括Uncredited可能的答案。
使用SPARQL的CONSTRUCT进行当前查询以获得三元组，该三元组允许表达以下规则：
数据文件（Beatles.ttl）
@prefix c: <http://beatlesExample/ns/class/> .
@prefix t: <http://beatlesExample/ns/title/> .
@prefix pi: <http://beatlesExample/ns/playsInstrument/> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix m: <http://beatlesExample/ns/musician/> .
t:MagicalMysteryTour a c:Song ;
rdfs:label "Magical Mystery Tour" ;
pi:acousticrhythmguitar m:JohnLennon ;
pi:bass m:PaulMcCartney ;
pi:drums m:RingoStarr ;
pi:leadguitar m:GeorgeHarrison ;
pi:percussion m:RingoStarr , m:NeilAspinall , m:MalEvans , m:GeorgeHarrison , m:JohnLennon ;
pi:piano m:PaulMcCartney ;
pi:trumpet m:ElgarHowarth , m:JohnWilbraham , m:DavidMason , m:RoyCopestake ;
pi:vocals m:JohnLennon , m:PaulMcCartney , m:GeorgeHarrison .
t:PennyLane a c:Song ;
rdfs:label "Penny Lane" ;
pi:acousticguitar m:JohnLennon ;
pi:backingvocals m:JohnLennon , m:GeorgeHarrison ;
pi:bassguitar m:PaulMcCartney ;
pi:doublebass m:FrankClarke ;
pi:drums m:RingoStarr ;
pi:electricguitar m:JohnLennon ;
pi:flutesorpiccolos m:PGoody , m:RaySwinfield , m:MannyWinters , m:DennisWalton ;
pi:guitar m:GeorgeHarrison ;
pi:handclaps m:GeorgeHarrison , m:JohnLennon , m:PaulMcCartney ;
pi:harmonium m:PaulMcCartney ;
pi:oboesorcoranglais m:DickMorgan , m:MikeWinfield ;
pi:piano m:JohnLennon , m:PaulMcCartney ;
pi:tambourine m:RingoStarr ;
pi:trumpetsorflugelhorn m:FreddyClayton , m:LeonCalvert , m:BertCourtley , m:DuncanCampbell , m:DavidMason ;
pi:tubularbells m:RingoStarr ;
pi:vocals m:PaulMcCartney .
t:NotASecondTime a c:Song ;
rdfs:label "Not A Second Time" ;
pi:acousticrhythmguitar m:JohnLennon ;
pi:bass m:PaulMcCartney ;
pi:drums m:RingoStarr ;
pi:piano m:GeorgeMartin ;
pi:vocals m:JohnLennon .
t:Yesterday a c:Song ;
rdfs:label "Yesterday" ;
pi:cello m:FranciscoGabarro ;
pi:guitar m:PaulMcCartney ;
pi:viola m:KennethEssex ;
pi:violin m:TonyGilbert , m:SidneySax ;
pi:vocals m:PaulMcCartney .
t:LosParanoias a c:Song ;
rdfs:label "Los Paranoias" ;
pi:acousticguitar m:PaulMcCartney ;
pi:percussion m:JohnLennon ;
pi:shaker m:RingoStarr ;
pi:vocals m:PaulMcCartney .
t:LikeDreamersDo a c:Song ;
rdfs:label "Like Dreamers Do" ;
pi:bass m:PaulMcCartney ;
pi:drums m:PeteBest ;
pi:leadguitar m:GeorgeHarrison ;
pi:rhythmguitar m:JohnLennon ;
pi:vocals m:PaulMcCartney .
t:IGotToFindMyBaby a c:Song ;
rdfs:label "I Got To Find My Baby" ;
pi:bass m:PaulMcCartney ;
pi:drums m:RingoStarr ;
pi:harmonica m:JohnLennon ;
pi:leadguitar m:GeorgeHarrison ;
pi:rhythmguitar m:JohnLennon ;
pi:vocals m:JohnLennon .
t:Revolution1 a c:Song ;
rdfs:label "Revolution 1" ;
pi:Hammondorgan m:PaulMcCartney ;
pi:acousticguitar m:JohnLennon ;
pi:backingvocals m:FrancieSchwartz , m:GeorgeHarrison , m:PaulMcCartney ;
pi:bass m:PaulMcCartney ;
pi:drums m:RingoStarr ;
pi:leadguitar m:GeorgeHarrison , m:JohnLennon ;
pi:piano m:PaulMcCartney ;
pi:trombone m:JPower , m:DonLang , m:BillPovey , m:RexMorris ;
pi:trumpet m:FreddyClayton , m:DerekWatkins ;
pi:vocals m:JohnLennon .
t:DizzyMissLizzy a c:Song ;
rdfs:label "Dizzy Miss Lizzy" ;
pi:Hammondorgan m:JohnLennon ;
pi:HohnerPianetelectricpiano m:PaulMcCartney ;
pi:bass m:PaulMcCartney ;
pi:cowbell m:RingoStarr ;
pi:double-trackedleadguitar m:GeorgeHarrison ;
pi:drums m:RingoStarr ;
pi:rhythmguitar m:JohnLennon ;
pi:vocals m:JohnLennon .
t:YesItIs a c:Song ;
rdfs:label "Yes It Is" ;
pi:acousticrhythmguitar m:JohnLennon ;
pi:bass m:PaulMcCartney ;
pi:drums m:RingoStarr ;
pi:harmonyvocals m:GeorgeHarrison , m:PaulMcCartney ;
pi:leadguitar m:GeorgeHarrison ;
pi:tambourine m:RingoStarr ;
pi:vocals m:JohnLennon .
t:IWannaBeYourMan a c:Song ;
rdfs:label "I Wanna Be Your Man" ;
pi:Hammondorgan m:GeorgeMartin ;
pi:backingvocals m:PaulMcCartney , m:JohnLennon ;
pi:bass m:PaulMcCartney ;
pi:drums m:RingoStarr ;
pi:leadguitar m:GeorgeHarrison ;
pi:maracas m:RingoStarr ;
pi:rhythmguitar m:JohnLennon ;
pi:vocals m:RingoStarr .
t:ThingsWeSaidToday a c:Song ;
rdfs:label "Things We Said Today" ;
pi:acousticrhythmguitar m:JohnLennon ;
pi:bass m:PaulMcCartney ;
pi:drums m:RingoStarr ;
pi:leadguitar m:GeorgeHarrison ;
pi:piano m:JohnLennon ;
pi:tambourine m:RingoStarr ;
pi:vocals m:PaulMcCartney .
t:HallelujahILoveHerSo
a c:Song ;
rdfs:label "Hallelujah, I Love Her So" ;
pi:bass m:StuartSutcliffe ;
pi:guitar m:GeorgeHarrison , m:PaulMcCartney , m:JohnLennon ;
pi:vocals m:PaulMcCartney .
t:OldBrownShoe a c:Song ;
rdfs:label "Old Brown Shoe" ;
pi:backingvocals m:JohnLennon , m:PaulMcCartney ;
pi:bass m:GeorgeHarrison ;
pi:drums m:RingoStarr ;
pi:guitar m:GeorgeHarrison , m:PaulMcCartney ;
pi:organ m:GeorgeHarrison ;
pi:piano m:PaulMcCartney ;
pi:vocals m:GeorgeHarrison .
t:GoodNight a c:Song ;
rdfs:label "Good Night" ;
pi:12violins m:Uncredited ;
pi:backingvocals m:MikeRedway , m:PatWhitmore , m:FredLucas , m:ValStockwell , m:IreneKing , m:IngridThomas , m:KenBarrie , m:RossGilmour ;
pi:celesta m:GeorgeMartin ;
pi:clarinet m:Uncredited ;
pi:doublebass m:Uncredited ;
pi:harp m:Uncredited ;
pi:horn m:Uncredited ;
pi:threecellos m:Uncredited ;
pi:threeflutes m:Uncredited ;
pi:threeviolas m:Uncredited ;
pi:vibraphone m:Uncredited ;
pi:vocals m:RingoStarr .
t:MemphisTennessee a c:Song ;
rdfs:label "Memphis, Tennessee" ;
pi:bass m:PaulMcCartney ;
pi:drums m:RingoStarr ;
pi:leadguitar m:GeorgeHarrison ;
pi:rhythmguitar m:JohnLennon ;
pi:vocals m:JohnLennon .
t:TicketToRide a c:Song ;
rdfs:label "Ticket To Ride" ;
pi:bass m:PaulMcCartney ;
pi:double-trackedleadvocals m:JohnLennon ;
pi:drums m:RingoStarr ;
pi:handclaps m:RingoStarr ;
pi:harmonyvocals m:PaulMcCartney ;
pi:leadguitar m:PaulMcCartney ;
pi:rhythmguitar m:GeorgeHarrison , m:JohnLennon ;
pi:tambourine m:RingoStarr .
t:Ob-La-DiOb-La-Da a c:Song ;
rdfs:label "Ob-La-Di, Ob-La-Da" ;
pi:acousticguitar m:GeorgeHarrison ;
pi:backingvocals m:JohnLennon , m:GeorgeHarrison ;
pi:bass m:PaulMcCartney ;
pi:bongo m:RingoStarr ;
pi:drums m:RingoStarr ;
pi:handclaps m:JohnLennon , m:PaulMcCartney , m:GeorgeHarrison , m:RingoStarr ;
pi:percussion m:RingoStarr ;
pi:piano m:JohnLennon ;
pi:threesaxophones m:Uncredited ;
pi:vocals m:PaulMcCartney .
t:LetItBe a c:Song ;
rdfs:label "Let It Be" ;
pi:backingvocals m:JohnLennon , m:LindaMcCartney , m:PaulMcCartney , m:GeorgeHarrison ;
pi:bassguitar m:PaulMcCartney ;
pi:cello m:Uncredited ;
pi:drums m:RingoStarr ;
pi:electricpiano m:BillyPreston ;
pi:leadguitar m:GeorgeHarrison ;
pi:maracas m:PaulMcCartney ;
pi:organ m:BillyPreston ;
pi:piano m:PaulMcCartney ;
pi:tenorsaxophone m:Uncredited ;
pi:twotrombones m:Uncredited ;
pi:twotrumpets m:Uncredited ;
pi:vocals m:PaulMcCartney .
t:IGotAWoman a c:Song ;
rdfs:label "I Got A Woman" ;
pi:bass m:PaulMcCartney ;
pi:drums m:RingoStarr ;
pi:leadguitar m:GeorgeHarrison ;
pi:rhythmguitar m:JohnLennon ;
pi:vocals m:JohnLennon .
t:TheSaints a c:Song ;
rdfs:label "The Saints" ;
pi:bass m:PaulMcCartney ;
pi:drums m:PeteBest ;
pi:leadguitar m:TonySheridan , m:GeorgeHarrison ;
pi:rhythmguitar m:JohnLennon ;
pi:vocals m:TonySheridan .
t:LendMeYourComb a c:Song ;
rdfs:label "Lend Me Your Comb" ;
pi:bass m:PaulMcCartney ;
pi:drums m:RingoStarr ;
pi:leadguitar m:GeorgeHarrison ;
pi:rhythmguitar m:JohnLennon ;
pi:vocals m:GeorgeHarrison , m:PaulMcCartney , m:JohnLennon .
t:BesameMucho a c:Song ;
rdfs:label "Besame Mucho" ;
pi:bass m:PaulMcCartney ;
pi:drums m:PeteBest ;
pi:leadguitar m:GeorgeHarrison ;
pi:rhythmguitar m:JohnLennon ;
pi:vocals m:PaulMcCartney .
诀窍是要认识到您可以将“约翰·列侬是唯一的歌手”改写为“除了约翰·列侬之外，没有其他歌手。”然后您可以使用FILTER NOT EXISTS，如下所示：
FILTER NOT EXISTS