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arXiv 0804.3029math.CO
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关于二元超立方体中识别码的大小

On the size of identifying codes in binary hypercubes

Svante Janson, Tero Laihonen

摘要:

我们考虑在二进制汉明空间F^n中识别码,即,在二元超立方体中。识别码的概念是由Karpovsky,Chakrabarty和Levitin在1998年提出的。目前,该主题形成了自己的主题,具有几种可能的应用,例如传感器网络。设C是F^n的一个子集。对于F^n的任意子集X,用I_r(X)=I_r(C;X)表示C中距离X中至少一个x为r的元素的集合。如果集合I_r(X)对于所有大小不超过l的子集X都是不同的,则称C为(r,<= l)-标识码。我们估计了在固定l和r/n收敛到(0,1)中某个数ρ的情况下这类码的最小尺寸。我们进一步证明了对于任意固定的l和略小于n/2的r,存在一个大小为O(n^{3/2})的码,并且对于l=2,给出了一个小码的显式构造,其中r是n/2-1的整数部分(最大可能值).

英文摘要:

We consider identifying codes in binary Hamming spaces F^n, i.e., in binary hypercubes. The concept of identifying codes was introduced by Karpovsky, Chakrabarty and Levitin in 1998. Currently, the subject forms a topic of its own with several possible applications, for example, to sensor networks. Let C be a subset of F^n. For any subset X of F^n, denote by I_r(X)=I_r(C;X) the set of elements of C within distance r from at least one x in X. Now C is called an (r,<= l)-identifying code if the sets I_r(X) are distinct for all subsets X of size at most l. We estimate the smallest size of such codes with fixed l and r/n converging to some number rho in (0,1). We further show the existence of such a code of size O(n^{3/2}) for every fixed l and r slightly less than n/2, and give for l=2 an explicit construction of small such codes for r the integer part of n/2-1 (the largest possible value).

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