简介:Aclassofnormal-likederivativesforfunctionswithlowregularitydefinedonLipschitzdomainsareintroducedandstudied.Itisshownthatthenewnormal-likederivatives,whicharecalledthegeneralizednormalderivatives,preservethemajorprop-ertiesoftheexistingstandardnormalderivatives.Thegeneralizednormalderivativesarethenappliedtoanalyzetheconvergenceofdomaindecompositionmethods(DDMs)withnonmatchinggridsanddiscontinuousGalerkin(DG)methodsforsecond-orderel-lipticproblems.Theapproximatesolutionsgeneratedbythesemethodsstillpossesstheoptimalenergy-normerrorestimates,eveniftheexactsolutionstotheunderlyingellipticproblemsadmitverylowregularities.