简介:AgraphGiscalledchromatic-choosableifitschoicenumberisequaltoitschromaticnumber,namelych(G)=χ(G).Ohba’sconjecturestatesthateverygraphGwith2χ(G)+1orfewerverticesischromaticchoosable.ItisclearthatOhba’sconjectureistrueifandonlyifitistrueforcompletemultipartitegraphs.Recently,Kostochka,StiebitzandWoodallshowedthatOhba’sconjectureholdsforcompletemultipartitegraphswithpartitesizeatmostfive.Butthecompletemultipartitegraphswithnorestrictionontheirpartitesize,forwhichOhba’sconjecturehasbeenverifiedarenothingmorethanthegraphsKt+3,2*(k-t-1),1*tbyEnotomoetal.,andKt+2,3,2*(k-t-2),1*tfort≤4byShenetal..Inthispaper,usingtheconceptoff-choosable(orL0-size-choosable)ofgraphs,weshowthatOhba’sconjectureisalsotrueforthegraphsKt+2,3,2*(k-t-2),1*twhent≥5.Thus,Ohba’sconjectureistrueforgraphsKt+2,3,2*(k-t-2),1*tforallintegerst≥1.
简介:<正>Foranoddfunctionf(x)definedonlyonafiniteinterval,thispaperdealswiththeexistenceofperiodicsolutionsandthenumberofsimpleperiodicsolutionsofthedifferentialdelayequation(DDE)(?)(t)=-f(x(t-1)).Byuseofthemethodofqualitativeanalysiscombinedwiththeconstructingofspecialsolutionsaseriesofinterestingresultsareobtainedontheseproblems.
简介:Inthispaper,wedealwithamodelforthesurvivalofredbloodcellswithperiodiccoefficientsx'(t)=-μ(t)x(t)+P(t)e~(-γ(t)x(t-τ(t))),t≥0.(*)AnewsufficientconditionforglobalattractivityofpositiveperiodicsolutionsofEq.(*)isobtained.OurcriterionimprovescorrespondingresultobtainedbyLiandWangin2005.
简介:UsingthemethodofGirsanovtransformation,weestablishtheTalagrand'sT2-inequalityfordiffusiononthepathspaceC([0,N],R^d)withrespecttoauniformmetric,withtheconstantindependentofN.ThisimprovestheknownresultsfortheL2-metric.
简介:Inthispaper,weobtainaresultthatimprovestheresultsofGovilandNwaeze,QaziandtheclassicalresultofRivlin.
简介:本文用临界点理论中的能量最小原理得到了一类具(q(t),P(t))-Laplacian项的二阶非自治系统存在周期解的充分条件.
简介:Weintroducethecategoryoft-foldmoduleswhichisafullsubcategoryofgradedmodulesoveragradedalgebra.Weshowthatthissubcategoryandhencethesubcategoryoft-Koszulmodulesarebothclosedunderextensionsandcokernelsofmonomorphisms.Westudytheone-pointextensionalgebras,andanecessaryandsufficientconditionforsuchanalgebratobet-Koszulisgiven.Wealsoconsidertheconditionssuchthatthecategoryoft-Koszulmodulesandthecategoryofquadraticmodulescoincide.
简介:给出了n阶带形状参数的三角多项式T-Bézier基函数.由带形状参数的三角多项式T-Bézier基组成的带形状参数的T-Bézier曲线,可通过改变形状参数的取值而调整曲线形状,随着形状参数的增加,带形状参数的T-Bézier曲线将接近于控制多边形,并且可以精确表示圆、螺旋线等曲线.阶数的升高,形状参数的取值范围将扩大.
简介:Letp(z)=a_0+a_1z+a_2z~2+a_3z~3+···+a_nz~nbeapolynomialofdegreen.Rivlin[12]provedthatifp(z)≠0intheunitdisk,thenfor0
简介:论证了零级υ值代数体函数w(z)在满足某些条件下T方向的存在性,同时给出了最大型Borel方向与T方向之间的关系.
简介:本文利用等价方程组,友矩阵与Jordan标准型,研究了n阶常系数线性非齐次常微分方程P(D)x=acose^t+bsine^t其中P(D)=D^n+a1D^n-1+…+an,D=1/dt,a1,a2,…a,a,b为任意实常数,在友矩阵具有n个不同的特征根的条件下,给出了求上述方程的特解的方法,最后给出一个详细的实例。