共查询到19条相似文献,搜索用时 78 毫秒
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本文研究了混合长度的删位纠错码的构造问题.利用组合设计的方法构造了长为{3,4,5}的完备删位纠错码T(2,{3,4,5},v),当v为正整数且v≠8时,得到了所有的T(2,{3,4,5},v)-码,并给出码字总数的一个上界,T(2,{3,4,5},v)-码的构造推广了长度为单一值的删位纠错码的构造结果. 相似文献
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设函数 $\alpha(t)$在$\bf R$上非负连续 和 $1\le{p}<+{\infty}$, 则 $L_{\alpha}^p=\{f: \int_{-{\infty}}^{\infty}|f(t)e^{-\alpha(t)}|^p\mathrm{d}t<{\infty}\}$ 是Banach空间. 本文中我们得到了一个复指数函数系在$L_{\alpha}^{p}$ 空间中稠密的充分必要条件. 相似文献
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唐矛宁 《应用数学与计算数学学报》2008,(2)
本文研究了标的资产价格服从连续时间It过程模型的金融市场的完备性问题。在允许有摩擦的金融市场中,当可允许投资策略取值于一个非空凸闭集时,给出了金融市场在内蕴完备条件下广义不完备的充分必要条件. 相似文献
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文[1]给出数列{(1+(1/n))n}与{(1+1/n)n+1}的单调性的新证,并结合2008年湖南理科压轴题作如下探究:研究数列{(1+1/n)n+a}(其中a为实数)的单调性,得出如下单调完备性定理: 相似文献
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证明了对于q≥17,当4q~5-5q~4-2q+1≤d≤4q~5-5q~4-q时,不存在达到Griesmer界的[n,k,d]_q码.此结果推广了Cheon等人在2005年和2008年的非存在性定理. 相似文献
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该文研究了随机函数列{tλn(ω)在加权Banach空间Cα中的完备性与闭包.其中Cα表示在正实轴上连续且满足当,t→ ∞时,|f(t)|e-α(t)→0的连续复函数组成的Banach空间. 相似文献
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利用Mawhin重合度拓展定理, 研究一类具有排斥型奇性的中立型Li''{e}nard方程周期问题. 在强奇性条件下, 获得周期正解存在性的新结果. 本文允许方程在无穷远点具有不定型奇性, 改进了已有文献中的相关结论. 相似文献
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Motivated by the construction of t‐deletion/insertion‐correcting codes, we consider the existence of directed PBDs with block sizes from K = {4, 5} and {4, 6}. The spectra of such designs are determined completely in this paper. For any integer {υ ≥ 4, a DB({4,5} ,1; υ) exists if and only if υ∉{6, 8, 9, 12, 14}, and a DB({4, 6}, 1; υ) exists if and only if υ ≡ 0,1 mod 3 and υ∉{9,15}. © 2001 John Wiley & Sons, Inc. J Combin Designs 9: 147–156, 2001 相似文献
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Existence of Perfect 3-Deletion-Correcting Codes 总被引:1,自引:0,他引:1
A. Mahmoodi 《Designs, Codes and Cryptography》1998,14(1):81-87
Bours [4] recently showed some constructions for perfect 2 and 3-deletion-correcting codes from combinatorial designs. He settled existence of perfect 2-deletion-correcting codes with words of length 4. However, the existence of perfect 3-deletion-correcting codes with words of length 5, or T*(2, 5, v), remained unsettled for v 7, 8 (mod 10) and v = 13, 14, 15, 16. In this paper we provide new constructions for these codes from combinatorial designs, and show that a T*(2, 5, v) exists for all v. 相似文献
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A word of length k over an alphabet Q of size v is a vector of length k with coordinates taken from Q. Let Q*4 be the set of all words of length 4 over Q. A T*(3, 4, v)‐code over Q is a subset C*? Q*4 such that every word of length 3 over Q occurs as a subword in exactly one word of C*. Levenshtein has proved that a T*(3, 4, vv)‐code exists for all even v. In this paper, the notion of a generalized candelabra t‐system is introduced and used to show that a T*(3, 4, v)‐code exists for all odd v. Combining this with Levenshtein's result, the existence problem for a T*(3,4, v)‐code is solved completely. © 2004 Wiley Periodicals, Inc. J Combin Designs 13: 42–53, 2005. 相似文献
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By a T
*(2, k, v)-code we mean a perfect4-deletion-correcting code of length 6 over an alphabet of size v, which is capable of correcting anycombination of up to 4 deletions and/or insertions of letters that occur in transmission of codewords. Thethird author (DCC Vol. 23, No. 1) presented a combinatorial construction for such codes and prove thata T
*(2, 6, v)-code exists for all positive integers v 3 (mod 5), with 12 possible exceptions of v. In this paper, the notion of a directedgroup divisible quasidesign is introduced and used to show that a T
*(2, 6,v)-code exists for all positive integers v 3 (mod 5), except possiblyfor v {173, 178, 203, 208}. The 12 missing cases for T
*(2,6, v)-codes with v 3 (mod 5) are also provided, thereby the existenceproblem for T
*(2, 6, v)-codes is almost complete. 相似文献
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A t‐wise balanced design ( at BD) of order v and block sizes from K , denoted by S ( t , K , v ), is a pair ( X , ??), where X is a v ‐element set and ?? is a set of subsets of X , called blocks , with the property that | B |∈ K for any B ∈?? and every t ‐element subset of X is contained in a unique block. In this article, we shall show that there is an S ( 3 , { 4 , 5 , 7 }, v ) for any positive integer v ≡ 7 ( mod12 ) with v ≠ 19 . Copyright © 2011 Wiley Periodicals, Inc. J Combin Designs 20:68–80, 2012 相似文献
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Let v be a positive integer and let K be a set of positive integers. A (v, K, 1)-Mendelsohn design, which we denote briefly by (v, K, 1)-MD, is a pair (X, B) where X is a v-set (of points) and B is a collection of cyclically ordered subsets of X (called blocks) with sizes in the set K such that every ordered pair of points of X are consecutive in exactly one block of B. If for all t =1, 2,..., r, every ordered pair of points of X are t-apart in exactly one block of B, then the (v, K, 1)-MD is called an r-fold perfect design and denoted briefly by an r-fold perfect (v, K, 1)-MD. If K = {k) and r = k - 1, then an r-fold perfect (v, (k), 1)-MD is essentially the more familiar (v, k, 1)-perfect Mendelsohn design, which is briefly denoted by (v, k, 1)-PMD. In this paper, we investigate the existence of 4-fold perfect (v, (5, 8}, 1)-Mendelsohn designs. 相似文献
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The existence of a (q, k, 1) difference family in GF(q) has been completely solved for k = 3. For k = 4, 5 partial results have been given by Bose, Wilson, and Buratti. In this article, we continue the investigation and show that the necessary condition for the existence of a (q, k, 1) difference family in GF(q), i.e., q ≡ 1 (mod k(k − 1)) is also sufficient for k = 4, 5. For general k, Wilson's bound shows that a (q, k, 1) difference family in GF(q) exists whenever q ≡ 1 (mod k(k − 1)) and q > [k(k − 1)/2]k(k−1). An improved bound on q is also presented. © 1999 John Wiley & Sons, Inc. J Combin Designs 7: 21–30, 1999 相似文献
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The basic necessary conditions for the existence of a (v, k, λ)-perfect Mendelsohn design (briefly (v, k, λ)-PMD) are v ≥ k and λ v(v − 1) ≡ 0 (mod k). These conditions are known to be sufficient in most cases, but certainly not in all. For k = 3, 4, 5, 7, very extensive investigations of (v, k, λ)-PMDs have resulted in some fairly conclusive results. However, for k = 6 the results have been far from conclusive, especially for the case of λ = 1, which was given some attention in papers
by Miao and Zhu [34], and subsequently by Abel et al. [1]. Here we investigate the situation for k = 6 and λ > 1. We find that the necessary conditions, namely v ≥ 6 and λ v(v − 1)≡0 (mod 6) are sufficient except for the known impossible cases v = 6 and either λ = 2 or λ odd.
Researcher F.E. Bennett supported by NSERC Grant OGP 0005320. 相似文献