LawsOfUnreliability

1.Computersareunreliable,buthumansareevenmoreunreliable.

2.Atthesourceofeveryerrorwhichisblamedonthecomputeryouwillfindatleasttwohumanerrors,includingtheerrorofblamingitonthecomputer.

3.Anysystemwhichdependsonhumanreliabilityisunreliable.

4.Undetectableerrorsareinfiniteinvariety,incontrasttodetectableerrors,whichbydefinitionarelimited.

5.Investmentinreliabilitywillincreaseuntilitexceedstheprobablecostoferrors,oruntilsomeoneinsistsongettingsomeusefulworkdone.

6.Theonlydifferencebetweenafoolandacriminalisthatthefoolwillattackasystemunpredictablyandonabroaderfront.

7.Asystemtendstogrowincomplexityinsteadofsimplicity,untiltheresultingunreliabilitybecomesintolerable.

8.Self-checkingsystemstendtohaveacomplexityinproportiontotheirinherentunreliability.

9.Theerror-detectionand-correctioncapabilitiesofanysystemserveasakeytounderstandingthetypesoferrorsitcannothandle.

10.Allrealprogramscontainerrorsuntilprovedotherwisewhichisimpossible.