High-order entropy-compressed text indexes
High-order entropy-compressed text indexes
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发表时间：
2003-01
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通讯作者：
R. Grossi;Ankur Gupta;J. Vitter
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作者：
R. Grossi;Ankur Gupta;J. Vitter
我们提出了一个新颖的后缀阵列的实现，该阵列在Alphabetσ上的n符号（或序列）之间表现出新的权衡，其中每个符号都由LG |σ| bits进行编码。后缀阵列仅使用NHH +σ位，同时保留全文索引功能，例如搜索O（m lg |σ| + polylog（n））时间的任何长度序列术语hh≤lg|σ|表示文本的htor顺序经验熵，这意味着我们的索引在空间中几乎是最佳的，除了较低的术语外。在论文中报告。
We present a novel implementation of compressed suffix arrays exhibiting new tradeoffs between search time and space occupancy for a given text (or sequence) of n symbols over an alphabet σ, where each symbol is encoded by lg|σ| bits. We show that compressed suffix arrays use just nHh + σ bits, while retaining full text indexing functionalities, such as searching any pattern sequence of length m in O(m lg |σ| + polylog(n)) time. The term Hh ≤ lg |σ| denotes the hth-order empirical entropy of the text, which means that our index is nearly optimal in space apart from lower-order terms, achieving asymptotically the empirical entropy of the text (with a multiplicative constant 1). If the text is highly compressible so that Hn = o(1) and the alphabet size is small, we obtain a text index with o(m) search time that requires only o(n) bits. Further results and tradeoffs are reported in the paper.