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A simple alphabet-independent FM-index.

Authors: Grabowski, Szymon; Mäkinen, Veli; Navarro, Gonzalo; Salinger, Alejandro;

A simple alphabet-independent FM-index.

Abstract

We design a succinct full-text index based on the idea of Huffman-compressing the text and then applying the Burrows-Wheeler transform over it. The resulting structure can be searched as an FM-index, with the benefit of removing the sharp dependence on the alphabet size, sigma, present in that structure. On a text of length n with zero-order entropy H-0, our index needs O(n(H-0 + 1)) bits of space, without any significant dependence on or. The average search time for a pattern of length m is O(m(H-0 + 1)), under reasonable assumptions. Each position of a text occurrence can be located in worst case time O((H-0 + 1) log n), while any text substring of length L can be retrieved in O((H-0 + 1)L) average time in addition to the previous worst case time. Our index provides a relevant space/time tradeoff between existing succinct data structures, with the additional interest of being easy to implement. We also explore other coding variants alternative to Huffman and exploit their synchronization properties. Our experimental results on various types of texts show that our indexes are highly competitive in the space/time tradeoff map.

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Chile
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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
0
Average
Average
Average
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