摘要
Weestablishtheconceptofshapesoffunctionsbyusingpartialdifferentialinequalites.Ourdefinitionaboutshapesincludessomeusualshapessuchasconvex,subharmonic,etc.,andgivesmanynewshapesoffunctions.Themainresultsshowthattheshapepreservingapproxi-mationhascloserelationtotheshapepreservingextension.Oneofourmainresultsshowsthatiff∈C(Ω)hassomeshapedefinedbyourdefinition,thenfcanbeuniformlyapproximatedbypolynomialsPn∈pn(n∈N)whichhavethesameshapeinΩ,andthedegreeoftheap-proximationisCω(f,n-β)withconstantsC,β>0.
出版日期
1992年02月12日(中国期刊网平台首次上网日期,不代表论文的发表时间)