共查询到20条相似文献,搜索用时 203 毫秒
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一个v 阶有向三元系,记为DTS(v,λ), 是指一个对子(X, B),这里X为v元集, B为X上一些可迁三元组(简称区组) 构成的集合, 使得X上每个由不同元素组成的有序对都恰在B的λ个区组中出现. 一个有向三元系的超大集,记为 OLDT(v,λ), 是指一个集合(Y{y}, AI)I, 其中Y为v+1元集, 每个(Y{y}, AI)是一个DTS(v,λ), 并且所有 AI 形成 Y上全部可迁三元组的分拆. 讨论OLDTS(v,λ)的存在性问题, 并且给出结论: 存在OLDTS(v,λ) 当且仅当 λ=1 且v≡0,1 (mod 3), 或 λ=3且v≠2. 相似文献
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李三系是从黎曼对称空间产生的三元运算的代数系统,近年来备受数学家们的重视.针对李三系的Frattini子系和基本李三系的问题进行了研究,给出了Frattini子系和基本李三系的一些性质,并证明了李三系的非嵌入定理,同时得到了幂零李三系是基本李三系的一个充要条件. 相似文献
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一个Mendelsohn (Directed, 或Hybrid)三元系 MTS$(v, \lambda)$~(DTS$(v, \lambda)$,或HTS$(v,\lambda))$, 是由$v$元集$X$ 上的一些循环(可迁,或循环和可迁)三元组(简称区组)构成的集合${\cal B}$, 使得$X$上每个由不同元素组成的有序对都恰在 ${\cal B}$的$\lambda$个区组中出现.本文主要讨论了这三类有向三元系之间的一种关联关系,给出猜想:任意MTS$(v,\lambda)$的区组关联图$G(\ 相似文献
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r×t阶Kirkman三连系构造的一种方法 总被引:9,自引:1,他引:8
侴万禧 《数学的实践与认识》2004,34(9):144-150
发现了 6n+3的高阶 Kirkman三连系构造方法 .阐明了 r× t阶 Kirkman三连系构造的基本理论 .给出了完全三分图的定义 ,并证明了关于 Kirkman三连系构造的命题 .介绍了 1 3 5阶 Kirkman三连系的构造过程 . 相似文献
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Mike J. Grannell Terry S. Griggs Edita Máčajová Martin Škoviera 《Journal of Graph Theory》2013,74(2):163-181
An ‐coloring of a cubic graph G is an edge coloring of G by points of a Steiner triple system such that the colors of any three edges meeting at a vertex form a block of . A Steiner triple system that colors every simple cubic graph is said to be universal. It is known that every nontrivial point‐transitive Steiner triple system that is neither projective nor affine is universal. In this article, we present the following results.
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广义Steiner三元系GS(2,3,n,g)等价于g+1元最优常重量码(n,3,3)。本文证明了GS(2,3,n,10)存在的必要条件n≡0,1(mod3),n≥12也是充分的。 相似文献
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《Discrete Mathematics》2022,345(9):112948
LR-designs, introduced by Lei (2002) [10], play an important role in the recursive constructions of large sets of Kirkman triple systems. In this paper, we mainly present some new infinite families of LR-designs and overlarge sets of Kirkman triple systems. 相似文献
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An Euler tour of a hypergraph (also called a rank‐2 universal cycle or 1‐overlap cycle in the context of designs) is a closed walk that traverses every edge exactly once. In this paper, using a graph‐theoretic approach, we prove that every triple system with at least two triples is eulerian, that is, it admits an Euler tour. Horan and Hurlbert have previously shown that for every admissible order >3, there exists a Steiner triple system with an Euler tour, while Dewar and Stevens have proved that every cyclic Steiner triple system of order >3 and every cyclic twofold triple system admits an Euler tour. 相似文献
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We give the first known examples of 6-sparse Steiner triple systems by constructing 29 such systems in the residue class 7 modulo 12, with orders ranging from 139 to 4447. We then present a recursive construction which establishes the existence of 6-sparse systems for an infinite set of orders. Observations are also made concerning existing construction methods for perfect Steiner triple systems, and we give a further example of such a system. This has order 135,859 and is only the fourteenth known. Finally, we present a uniform Steiner triple system of order 180,907. 相似文献
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E. F. Assmus Jr. 《Designs, Codes and Cryptography》1998,13(1):31-49
We attach a graph to every Steiner triple system. The chromatic number of this graph is related to the possibility of extending the triple system to a quadruple system. For example, the triple systems with chromatic number one are precisely the classical systems of points and lines of a projective geometry over the two-element field, the Hall triple systems have chromatic number three (and, as is well-known, are extendable) and all Steiner triple systems whose graph has chromatic number two are extendable. We also give a configurational characterization of the Hall triple systems in terms of mitres. 相似文献
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Myra B. Cohen Charles J. Colbourn Lee A. Ives Alan C. H. Ling. 《Mathematics of Computation》2002,71(238):873-881
There are 50,024 Kirkman triple systems of order 21 admitting an automorphism of order 2. There are 13,280 Kirkman triple systems of order 21 admitting an automorphism of order 3. Together with the 192 known systems and some simple exchange operations, this leads to a collection of 63,745 nonisomorphic Kirkman triple systems of order 21. This includes all KTS(21)s having a nontrivial automorphism group. None of these is doubly resolvable. Four are quadrilateral-free, providing the first examples of such a KTS(21).
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Alphonse Baartmans Ivan Landjev Vladimir D. Tonchev 《Designs, Codes and Cryptography》1996,8(1-2):29-43
The binary code spanned by the rows of the point byblock incidence matrix of a Steiner triple system STS(v)is studied. A sufficient condition for such a code to containa unique equivalence class of STS(v)'s of maximalrank within the code is proved. The code of the classical Steinertriple system defined by the lines in PG(n-1,2)(n3), or AG(n,3) (n3) is shown to contain exactly v codewordsof weight r=(v-1)/2, hence the system is characterizedby its code. In addition, the code of the projective STS(2n-1)is characterized as the unique (up to equivalence) binary linearcode with the given parameters and weight distribution. In general,the number of STS(v)'s contained in the code dependson the geometry of the codewords of weight r. Itis demonstrated that the ovals and hyperovals of the definingSTS(v) play a crucial role in this geometry. Thisrelation is utilized for the construction of some infinite classesof Steiner triple systems without ovals. 相似文献
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A 2‐class regular partial Steiner triple system is a partial Steiner triple system whose points can be partitioned into 2‐classes such that no triple is contained in either class and any two points belonging to the same class are contained in the same number of triples. It is uniform if the two classes have the same size. We provide necessary and sufficient conditions for the existence of uniform 2‐class regular partial Steiner triple systems. 相似文献