雨课堂学堂在线学堂云《Information Theory（北京理工）》单元测试考核答案

第1题Sourcecodingisprimarilyconcernedwithincreasingredundancyinthetransmitteddatatoensureerrordetectionandcorrection.()第2题Huffmancodingisanexampleoflosslesssourcecoding.()第3题Informationentropyquantifiestheamountofcertaintyinamessage.()第4题Thelevelofuncertaintyinasystemincreaseswith:()AFewerpossibleoutcomesBManypossibleoutcomesCHigh-probabilityoutcomesDLow-importanceinformation第5题Whatquantifiestheamountofuncertaintyorinformationcontentinamessage?()ADatasizeBEntropyCSpeedDBandwidth第6题Whatisthetermfortransmittingacertainamountofinformationintheshortestpossibletimeandwiththeleastnumberofdevices?()AEfficiencyBEffectivenessCSpeedDOptimization第7题WhichofthefollowingisNOTafundamentalconceptinInformationTheory?()AEntropyBMutualInformationCDataCompressionDQuantumEntanglement第8题Whichofthefollowingisameasureoftheamountofuncertaintyorinformationcontentinamessage?()ABandwidthBDataRateCInformationEntropyDChannelCapacity第9题Whatdoesthetheoryofsourcecodinginvolve?()ARepresentinginformationinacompactandefficientmannerBMeasuringthephysicalsizeofdatastoragedevicesCAnalyzingthespeedofdatatransmissionDEnsuringdataistransmittedinanalogformat第10题WhatisthemainadvantageofusingHuffmancodingfordatacompression?()AItmaximizesthespeedofdatatransmissionBItensuresdataistransmittedsecurelyCItprovideshighcompressionrateswithminimallossofinformationDItiseasytoimplementandunderstand第11题WhichofthefollowingisNOTanapplicationofinformationtheory?()AGeneticsandheredityBNeuralcommunicationinthenervoussystemCWeatherforecastingDMachinelearningalgorithmsinAI第12题Whatiscryptographyconcernedwith?()AEnsuringinformationistransmittedinanalogformatBIncreasingtheredundancyoftransmitteddataCSecuringinformationbytransformingitintoanunreadableformatDCompressingdatatoreducestoragerequirements第13题Whatisthemainideabehindchannelcoding?()AToimprovethespeedofdatatransmissionBToremoveunnecessarydatafromtransmittedinformationCToensurereliabletransmissionofinformationeveninthepresenceofnoiseDTomaximizethestoragecapacityofdatadevices第14题Whoisconsideredthe‘FatherofInformationTheory’?()ARalphHartleyBNorbertWienerCClaudeElwoodShannonDRichardHamming第15题Whatistheprimarygoalofinformationtheory?()AToimprovethespeedofcomputersBTodevelopnewcommunicationtechnologiesCToachievespecificobjectiveswiththehelpofinformationDTostudythephysicalpropertiesofdatatransmissionmedia第1题Conditionalself-informationcanbezeroiftheoccurrenceofoneeventmakesanothereventcertain.()第2题ThejointprobabilityspaceofanN-symbolextensionofadiscretememorylesssourceincludesallpossiblesequencesofsymbols.()第3题Pointwisemutualinformationcanonlybepositive.()第4题Jointself-informationistheuncertaintyofthejointsymbol(xk,yj).()第5题InanN-symbolextensionofaDMS,ifsymbolsareindependentandidenticallydistributed,howdoesthejointentropychangewithN?()AItdecreaseslinearlywithNBItincreaseslinearlywithNCItremainsconstantregardlessofNDItincreasesexponentiallywithN第6题WhatdoesthehomogeneityofaMarkovchainimply?()ATransitionprobabilitieschangeovertimeBTransitionprobabilitiesdonotchangeovertimeCInitialdistributionchangesovertimeDInitialdistributiondoesnotchangeovertime第7题Toimprovetheefficiencyofinformationtransmission,oneshould:()AIncreasetheentropyofthesourceBReducetheredundancyofthesourceCIncreasethelengthofthemessageDDecreasethenumberofsymbols第8题TheChapman-Kolmogorovequationsdescribe:()AThetransitionprobabilitiesbetweenstatesBThestationarydistributionoftheMarkovchainCThesumoftheprobabilitiesofmultiplestepsDTheinitialdistributionoftheMarkovchain第9题TheentropyrateRofadiscretememorysourceisdefinedas:()ATheaverageamountofinformationpersymbolBThetotalamountofinformationovertimeCThemaximumpossibleentropyDTheminimumpossibleentropy第10题Whichofthefollowingstatementsaboutpointwisemutualinformationiscorrect?()AItcanonlybepositiveBItcanbepositiveornegativeCItisalwayszeroDItisundefined第11题WhatdoesthehomogeneityofaMarkovchainimply?()ATransitionprobabilitieschangeovertimeBTransitionprobabilitiesdonotchangeovertimeCInitialdistributionchangesovertimeDInitialdistributiondoesnotchangeovertime第12题Whenasourcehasmorepossiblesymbolsandtheirprobabilitiesaredistributeduniformly,theentropy()AIncreasesBDecreasesCRemainsconstantDBecomeszero第13题Thepropertythataddingzero-probabilityeventsdoesnotaffectentropyiscalled()ASymmetryBExpansibilityCNon-negativityDAdditivity第14题Theentropyofacontinuousrandomvariableiscalled()ADifferentialentropyBMutualentropyCAverageentropyDNoneoftheabove第15题Theentropyofasourcecanbeaffectedbythepermutationofitsprobabilities.TrueorFalse?()ATrueBFalse3.11Exercises第1题Inanadditivenoisechannel,thecapacityofthechannelisindependentofthenoisepower.()第2题ThechannelcapacityofawaveformchanneloveradurationTcanbeexpressedas:CT(Ps)=limN→∞maxfX¯(x){I(X¯;Y¯);E(X2¯)≤PS}.()第3题Acontinuouschannelreferstoachannelwithcontinuoustimeandcontinuousamplitude.()第4题ThechannelcapacityoftheN-thextensionofadiscretememory-lesschannelismax

∑k=1NI(Xk;Yk).()第5题Doubtfulentropyrepresentstheamountofinformationlostinthechanneloutputduetonoiseinterference.()第6题Theoutputsymbolsetreferstothesetofallpossibleoutputsignalsinachannel.()第7题Thecapacityofadiscretechannelisrelatedtotheprobabilitydistributionofinputsymbols.()第8题Thecorrectstatementsaboutwhitenoiseare()AwhitenoiseisuniformlydistributedacrossthefrequencyrangeBwhitenoiseisnon-uniformlydistributedacrossthefrequencyrangeCwhitenoiseexistsinrealityDwhitenoiseisanidealizednoisesignalanddoesnotexistinreality正确答案：AD第9题Inacascadedcommunicationsystem,whatistheeffectofusingalow-passfilterasthesecondchannelinthecascade()AItwillincreasethehigh-frequencycomponentsofthesignal.BItwillcauseattenuationofhigh-frequencysignals.CItwillreducetheoverallbandwidthofthesystem.DItwillnotaffectthefrequencyresponseofthesystem.第10题Forsuccessfulinformationtransmission,wecanintroduce()betweenthesourceandthechannel.()AanADCBalatchCanencoderDadecoder第11题Foranadditivenoisechannel,theinputX,outputY,andnoiseZsatisfy()AX=YZBX=Y+ZCY=XZDY=X+Z第12题Thechannelcapacityofanindependentparallelchannelis()AtheproductofthechannelcapacitiesofitsconstituentchannelsBthesumofthechannelcapacitiesofitsconstituentchannelsClessthanthesumofthechannelcapacitiesofitsconstituentchannelsDbasedonthemathematicalmodeloftheentireparallelchannel第13题ForanN-stagecascadeofchannelswithtransitionmatricesQ1,Q2,…QN,thetransitionprobabilitymatrixfortheentirecascadeis:()A1/Q=Q1,Q2,…QN

B1/Q= 1/Q1+ 1/Q2+…+ 1/QNCQ=Q1+Q2+…+QN

DQ=Q1

Q2

…

QN第14题Whatistherelationshipbetweenmutualinformationandentropy()AI(X¯;Y¯)=H(X¯)−H(X¯Y¯)BI(X¯;Y¯)=H(Y¯)−H(X¯Y¯)CI(X¯;Y¯)=H(X¯)−H(X¯|Y¯)DI(X¯;Y¯)=H(Y¯)−H(X¯|Y¯)第15题ForaDMCwhichcouldberepresentedasdiagram,thecorrecttransitionprobabilitymatrixis()A．．PY|X=[0．10．910]B．．PY|X=[010．10．9]C．．PY|X=[100．10．9]D．．PY|X=[100．90．1]4.6Exercises第1题InHuffmancoding,thefrequencyofthecombinedsymbolisthe__________ofthetwofrequenciesmerged.()ASumBAverageCDifferenceDProduct第2题Theoptimalencodingofasourceisachievedbyminimizingthe__________ofthecode.()ABitrateBLengthCRedundancyDComplexity第3题Forasourcewithtwosymbols,wherethefirstsymbolhasaprobabilityof0.5andthesecondsymbolhasaprobabilityof0.5,theentropyis:()A0.5B1C2Dlog₂2第4题Theminimumcodelengthrequiredforasourceisequalto:()AEntropyBThenumberofsymbolsCFrequencyDFixedlength第5题Insourcecoding,theredundancyisremovedby:()ACompressionalgorithmsBOptimalencodingCDictionaryalgorithmsDEncodingtables第6题Huffmancodingalwaysgeneratesa__________tree.()ACompleteBBinaryCHuffmanDSkewed第7题Forasourcewithuniformprobabilitydistributionand8symbols,theentropyis:()A1bitB3bitsC8bitsDlog₂8第8题ForasourcewithNsymbols,thelowerboundfortheoptimalaveragecodelengthis:()Alog₂NBNC1D0第9题Huffmancodingisa_____