简介:Problemsaboutdensityareremarkableinthetheoryofdegreesofunsolvability.Owingtotheirdifficultyfewresultshavebeenobtainedtillnow.Sacks1964showedthatther.e.degreesaredense;Fejer1980showedthatnonbrachingdegreesaredenseinther.e.degrees,thisisthefirstnontrivialdefinablesubsetofthedegreesknowntobedense.
简介:Inthispaper,wederivetwogeneralparameterizedboundariesoffinitedifferenceschemeforVee’sPDEwhichisusedtopricebothfixedandfloatingstrikeAsianoptions.Usingthesetwoboundaries,wecandealwithallkindsofsituations,especially,someextremecases,likeoverhighvolatility,verysmallvolatility,etc,underwhichtheAsianoptionisusuallymispricedinmanyexistingnumericalmethods.Numericalresultsshowthatourboundariesareprettyefficient.
简介:Usingrecursivemethod,thispaperstudiesthequeuesizepropertiesatanyepochn+inGeom/G/1(E,SV)queueingmodelwithfeedbackunderLASDA(latearrivalsystemwithdelayedaccess)setup.Somenewresultsabouttherecursiveexpressionsofqueuesizedistributionatdifferentepoch(n+,n,n-)areobtained.Furthermoretheimportantrelationsbetweenstationaryqueuesizedistributionatdifferentepochsarediscovered.TheresultsaredifferentfromtherelationsgiveninM/G/1queueingsystem.Themodeldiscussedinthispapercanbewidelyappliedinmanykindsofcommunicationsandcomputernetwork.
简介:设G(V,E)是简单连通图,T(G)为图G的所有顶点和边构成的集合,并设C是k-色集(k是正整数),若T(G)到C的映射f满足:对任意uv∈E(G),有f(u)≠f(v),f(u)≠f(uv),f(v)≠f(uv),并且C(u)≠C(v),其中C(u)={f(u)}∪{f(uv)|uv∈E(G)}.那么称f为图G的邻点可区别E-全染色(简记为k-AVDETC),并称χ_(at)~e(G)=min{k|图G有k-邻点可区别E-全染色}为G的邻点可区别E-全色数.图G的中间图M(G)就是在G的每一个边上插入一个新的顶点,再把G上相邻边上的新的顶点相联得到的.探讨了路、圈、扇、星及轮的中间图的邻点可区别E-全染色,并给出了这些中间图的邻点可区别E-全色数.
简介:深化对本性谱的认识;给出∑_e~n(n≥2)型Banach空间上的摄动类问题的反面回答.