环IF_pm[u]/〈u~a〉上一类常循环码

本文研究有限链环上一类λ-常循环码.利用x~n-1在R_a[x]上可唯一分解为两两互素的首一基本不可约多项式乘积,刻画了R_a中长为p~sn的所有λ-常循环码,推广了开晓山等人在文献[4]中的结果.     

环R=F_q+uF_q+…+u~(s-1)F_q上λ-常循环码的深度分布和周期分布

讨论了环R=F_q+uF_q+…+u~(s-1)F_q上λ-常循环码的深度分布、周期分布和有限域F_q上λ-常循环码的深度分布、周期分布的关系,并由有限域上λ-常循环码的深度分布和周期分布给出了环R上λ-常循环码的深度分布和周期分布.     

Z_pZ_p[u]-加性循环码

该文研究了Z_pZ_p[u]-加性循环码,其中p是素数,u~2=0.文中证明了(1-u)-加性常循环码与加性循环码同构,构造了Z_pZ_p[u]到Z_p~(α+pβ)的Gray映射,并证明了(1-u)-加性常循环码的Gray象是一个广义的准循环码.此外研究了Z_pZ_p[u]-加性循环码的结构,给出了Z_pZ_p[u]-加性循环码的最小生成集.     

环F_p+vF_p上一类常循环码的周期分布

文章研究了有限环R=F_p+vF_p上一类任意长度的θ-常循环码的周期分布,其中v~2=v和θ=λ+v u.利用环R上θ-常循环码的结构的分解,将该环上这类常循环码的周期转化成两个对应的常循环码的周期的乘积.     

环Z_(p~m)上一类常循环码的周期分布

设λ是环Z_(p~m)的单位群中阶为l的元素,且l与p互素,本文研究了Z_(p~m)上长度为n的λ-常循环码的周期分布,其中gcd p(,n)=1.通过对环Z_(p~m)上长度为n的λ-常循环码结构的直和分解,给出其周期分布的计算公式.     

环Fp+vFp上互补对偶常循环码

本文研究了环F_p+vF_p上互补对偶（1-2v）-常循环码.利用环F_p+vF_p上（1-2v）-常循环码的分解式C=vC_1-v ⊕（1-v）C_v,得到了环F_p+vF_p上互补对偶（1-2v）-常循环码的生成多项式.然后借助从F_p+vF_p到F_p²的Gray映射,证明了环F_p+vF_p上互补对偶（1-2v）-常循环码的Gray像是F_p的互补对偶循环码.     

环Z_4+uZ_4上一类重根常循环码

设R=Z_4+uZ_4,R_n=R[x]/(x~n-(2u-1)),其中u~2=0,n=2~e.通过对环R上码长为n的(2u-1)-常循环码结构的研究,得到这些码的生成元,并对环R上码长为n的所有(2u-1)-常循环码进行分类,而且研究了该环上(2u-1)-常循环码的Hamming距离分布.最后给出环R上码长为n的(2u-1)-常循环码的对偶码的结构以及环R上码长为n的自正交与自对偶的(2u-1)-常循环码.     

有限非链环Fq+vFq上的2维斜常循环码

令R=F_q+vF_q是一个有限非链环,其中q是一个奇素数的方幂,v²=v.文章利用二元斜多项式环R[x,y;ρ,θ]来研究环R上的2维斜常循环码的代数结构和相关性质,其中ρ和θ是环R上的两个自同构映射.基于中国剩余定理,文章确定了环R上2维(α₁+β₁v,α₂+β₂v)-斜常循环码的生成元结构并且考虑了它们的Gray象,其中α₁+β₁v和α₂+β₂v都是环R上的可逆元.此外,文章研究了环R上2维(α₁+β₁v,α₂+β₂v)-斜常循环码的对偶码并且确定了对偶码子码的生成元结构.     

环F_p+vF_p上互补对偶常循环码（英文）

本文研究了环F_p+_vF_p上互补对偶(1-2v)-常循环码.利用环F_p+_v F_p上(1-2v)-常循环码的分解式C=_vC_(1-v)⊕(1-v)C_v,得到了环F_p+_v F_p上互补对偶(1-2v)-常循环码的生成多项式.然后借助从F_p+_v F_p到F_p~2的Gray映射,证明了环F_p+_vF_p上互补对偶(1-2v)-常循环码的Gray像是F_p的互补对偶循环码     

环F_2+uF_2上偶长的(1+u)-常循环码

给出了环F2+uF2上任意偶长的(1+u)-常循环码的结构,确定了给定偶长度F2+uF2上(1+u)-常循环码的数目.通过Gray映射,得到了F2+uF2上偶长的(1+u)-常循环码的二元象.     

关于环Fpm+uFpm+u2Fpm上循环码的注记

本文研究了环F_p^m+uF_p^m+u²F_p^m上长度为p^s的循环码分类.通过建立环F_p^m+uF_p^m+u²F_p^m到环F_p^m+uF_p^m的同态,给出了环F_p^m+uF_p^m+u²F_p^m上长度为p^s的循环码的新分类方法.应用这种方法,得到了环F_p^m+uF_p^m+u²F_p^m长度为p^s的循环码的码词数.     

Cyclotomic numbers and primitive idempotents in the ring GF(q)[x]/(x−1)

Let q be an odd prime power and p be an odd prime with gcd(p,q)=1. Let order of q modulo p be f, and q^f=1+pλ. Here expressions for all the primitive idempotents in the ring R_pⁿ=GF(q)[x]/(x^pn−1), for any positive integer n, are obtained in terms of cyclotomic numbers, provided p does not divide λ if n2. The dimension, generating polynomials and minimum distances of minimal cyclic codes of length pⁿ over GF(q) are also discussed.     

环Fq+uFq+vFq上的循环码和量子码

本文研究了环R=F_q+uF_q+vF_q(u²=u,v²=v,uv=vu=0)上的循环码构造量子码的方法.利用环R上循环码的分解与生成多项式,给出了R上一个循环码可以构造量子码的一个充要条件.作为这类循环码的应用,得到了新的非二元量子码.     

On some special codes over Fp + uFp + uFp

We define a new map between codes over F_p + uF_p + u²F_p and F_p which is different to that defined in [2]. It is proved that the image of the linear cyclic code over the commutative ring F_p + uF_p + u²F_p with length n under this map is a distance-invariant quasi-cyclic code of index p² with length p²n over F_p. Moreover, it is proved that, if (n, p) = 1, then every code with length p²n over F_p which is the image of a linear (1 − u²)-cyclic code with length n over F_p + uF_p + u²F_p under this map is permutation equivalent to a quasi-cyclic code of index p².     

Some remarks on the Schr?dinger equation with a potential in LrtLsx

We study the dispersive properties of the linear Schr?dinger equation with a time-dependent potential V(t,x). We show that an appropriate integrability condition in space and time on V, i.e. the boundedness of a suitable L^r_tL^s_x norm, is sufficient to prove the full set of Strichartz estimates. We also construct several counterexamples which show that our assumptions are optimal, both for local and for global Strichartz estimates, in the class of large unsigned potentials V ∈L^r_tL^s_x. Support. The authors are partially supported by the Research Training Network (RTN) HYKE and by grant HPRN-CT-2002-00282 from the European Union. The third author is supported also by INDAM     

Very tight embeddings of subspaces ofLp, 1 =p< 2, intolp n

We prove that for 1 p < r < 2, every n-dimensional subspace E of L _r, in particular l _r ⁿ , well-embeds into l _p ^m for some m (1 + $$\epsilon$$)n, where well depends on p, r, and the arbitrary $$\epsilon$$ > 0, but not on n.     

Ueber das volle Formensystem der tern?ren biquadratischen Formf=x13x2+x23x3+x33x1

Ohne ZusammenfassungHieizu cme Tale     

Une question sur les équations xm ? ym = Rzn (A Question on the Equations xm ? ym = Rzn)

Let m and n be integers at least two and R be a nonzero natural number. In this paper, we study the problem of the determination of the proper solutions of the Diophantine equation x ^m – y ^m equals; Rz ⁿ . We raise a question concerning the existence of any proper nontrivial solution of this equation, in case some precise conditions are satisfied by the triple (m, n, R). We prove some results about it.