Softwareentitiesaremorecomplexfortheirsizethanperhapsanyotherhumanconstruct,becausenotwopartsarealike(atleastabovethestatementlevel).Iftheyare,wemakethetwosimilarpartsintoone,a(1),openorclosed.Inthisrespectsoftwaresystemsdifferprofoundlyfromcomputers,buildings,orautomobiles,whererepeatedelementsabound.Digitalcomputersarethemselvesmorecomplexthanmostthingspeoplebuild;theyhaveverylargenumbersofstates.Thismakesconceiving,describing,andtestingthemhard.Softwaresystemshaveordersofmagnitudemore(2)thancomputersdo.Likewise,ascaling-upofasoftwareentityisnotmerelyarepetitionofthesameelementsinlargersize;itisnecessarilyanincreaseinthenumberofdifferentelements.Inmostcases,theelementsinteractwitheachotherinsome(3)fashion,andthecomplexityofthewholeincreasesmuchmorethanlinearly.Thecomplexityofsoftwareisa(an)(4)property,notanaccidentalone.Hencedescriptionsofasoftwareentitythatabstractawayitscomplexityoftenabstractawayitsessence.Mathematicsandthephysicalsciencesmadegreatstridesforthreecenturiesbyconstructingsimplifiedmodelsofcomplexphenomena,deriving,propertiesfromthemodels,andverifyingthosepropertiesexperimentally.Thisworkedbecausethecomplexities(5)inthemodelswerenottheessentialpropertiesofthephenomena.Itdoesnotworkwhenthecomplexitiesaretheessence.Manyoftheclassicalproblemsofdevelopingsoftwareproductsderivefromthisessentialcomplexityanditsnonlinearincreaseswithsize.Notonlytechnicalproblemsbutmanagementproblemsaswellcomefromthecomplexity. 2、____
A.states B.parts C.conditions D.expressions正确答案A
