简介:Theauthorconsidersthelife-spanofclassicalsolutionstoCauchyproblemforgeneralfirstorderquasilinearstrictlyhyperbolicsystemsintwoindependentvariableswith"slow"decayinitialdata.Byconstructinganexample,firstitisillustratedthattheclassicalsolutiontothiskindofCauchyproblemmayblowupinafinitetime,evenifthesystemisweaklylinearlydegenerate.Thensomelowerboundsofthelife-spanofclassicalsolutionsaregiveninthecasethatthesystemisweaklylinearlydegenerate.Theseestimatesimplythat,whenthesystemisweaklylinearlydegenerate,theclassicalsolutionexistsalmostgloballyintime.Finally,itisprovedthatTheorems1.1-1.3in[2]arestillvalidforthiskindofinitialdata.