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arXiv 0907.0001math.COcs.ITmath.IT
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关于完全着色与完全正则码的权重分布

On weight distributions of perfect colorings and completely regular codes

Denis Krotov

摘要:

一个图的顶点着色称为“完美”,如果对于任何两个颜色$a$和$b$,一个颜色-$a$顶点$x$的颜色-$b$邻居的数量不依赖于$x$的选择,也就是说,只依赖于$a$和$b$(顶点集的相应划分称为“公平”)。一个顶点集被称为“完全正则”,如果根据距离这个集合的着色是完美的。所谓染色关于集合的“权重分布“是指每种颜色在距离集合的每一个距离上的顶点数的信息。研究了图关于完全正则集(特别是距离正则图关于顶点)的完美染色(公平划分)的权重分布。我们展示了如何计算这个分布的知识的颜色组成的集合。对于完全正则集的某些部分情形,我们导出了权重分布的显式公式。由于任何(其他)完全正则集本身生成完美着色,这给出了从其参数计算任何完全正则集的权重分布的通用公式。在Hamming图的情况下,我们证明了一个非常简单的公式的重量计数器的任意完美染色。暗号:完全正规码公平分割;分区设计;完美的着色;结构完善;规则划分;权重分布;重量计数器

英文摘要:

A vertex coloring of a graph is called "perfect" if for any two colors $a$ and $b$, the number of the color-$b$ neighbors of a color-$a$ vertex $x$ does not depend on the choice of $x$, that is, depends only on $a$ and $b$ (the corresponding partition of the vertex set is known as "equitable"). A set of vertices is called "completely regular" if the coloring according to the distance from this set is perfect. By the "weight distribution" of some coloring with respect to some set we mean the information about the number of vertices of every color at every distance from the set. We study the weight distribution of a perfect coloring (equitable partition) of a graph with respect to a completely regular set (in particular, with respect to a vertex if the graph is distance-regular). We show how to compute this distribution by the knowledge of the color composition over the set. For some partial cases of completely regular sets, we derive explicit formulas of weight distributions. Since any (other) completely regular set itself generates a perfect coloring, this gives universal formulas for calculating the weight distribution of any completely regular set from its parameters. In the case of Hamming graphs, we prove a very simple formula for the weight enumerator of an arbitrary perfect coloring. Codewords: completely regular code; equitable partition; partition design; perfect coloring; perfect structure; regular partition; weight distribution; weight enumerator.

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