Softwareentitiesaremorecomplexfor theirsizethanperhapsanyotherhumanconstruct,becausenotwopartsare alike(atleastabovethestatementlevel).Iftheyare,wemakethetwo similarpartsintoone,a(71),openorclosed.Inthisrespectsoftwaresystemsdiffer profoundlyfromcomputers,buildings,orautomobiles,whererepeatedelements abound. Digitalcomputersarethemselvesmore complexthanmostthingspeoplebuild;theyhaveverylargenumbersofstates. Thismakesconceiving,describing,andtestingthemhard.Softwaresystemshave ordersofmagnitudemore(72)thancomputersdo. Likewise,ascaling-upofasoftwareentity isnotmerelyarepetitionofthesameelementsinlargersize;itisnecessarilyanincreasein thenumberofdifferentelements.Inmostcases,theelementsinteractwith eachotherinsome(73)fashion,and thecomplexityofthewholeincreasesmuchmorethanlinearly. Thecomplexityofsoftwareisa(an)(74)property,not anaccidentalone.Hencedescriptionsofasoftwareentitythatabstractaway itscomplexityoftenabstractawayitsessence.Mathematicsandthephysical sciencesmadegreatstridesforthreecenturiesbyconstructingsimplified modelsofcomplexphenomena,derivingpropertiesfromthemodels,andverifying thosepropertiesexperimentally.Thisworkedbecausethecomplexities(75)inthemodels werenottheessentialpropertiesofthephenomena.Itdoesnotworkwhenthe complexitiesaretheessence. Manyoftheclassicalproblemsof developingsoftwareproductsderivefromthisessentialcomplexityanditsnonlinearincreaseswith size.Notonlytechnicalproblemsbutmanagementproblemsaswellcomefromthecomplexity.
A.fixed B.included C.ignored D.stabilized正确答案C
