Search results
Results from the WOW.Com Content Network
Suffix arrays are closely related to suffix trees: . Suffix arrays can be constructed by performing a depth-first traversal of a suffix tree. The suffix array corresponds to the leaf-labels given in the order in which these are visited during the traversal, if edges are visited in the lexicographical order of their first character.
In the array, each suffix is represented by an integer pair (,) which denotes the suffix starting from position in . In the case where different strings in have identical suffixes, in the generalized suffix array, those suffixes will occupy consecutive positions. However, for convenience, the exception can be made where repeats will not be listed.
Augmenting the suffix array with the LCP array allows one to efficiently simulate top-down and bottom-up traversals of the suffix tree, [1] [2] speeds up pattern matching on the suffix array [3] and is a prerequisite for compressed suffix trees.
You can find the following characteristics in a suffix tree that uses Ukkonen's algorithm: Implicit suffix tree T i+1 is built on top of implicit suffix tree T i. At any given time, Ukkonen's algorithm builds the suffix tree for the characters seen so far and so it has on-line property, allowing the algorithm to have an execution time of O(n).
Compressed suffix arrays are a general class of data structure that improve on the suffix array. [1] [2] These data structures enable quick search for an arbitrary string with a comparatively small index. Given a text T of n characters from an alphabet Σ, a compressed suffix array supports searching for arbitrary patterns in T.
An alternative to building a generalized suffix tree is to concatenate the strings, and build a regular suffix tree or suffix array for the resulting string. When hits are evaluated after a search, global positions are mapped into documents and local positions with some algorithm and/or data structure, such as a binary search in the starting ...
One may also make the observation that mathematically, the encoded string can be computed as a simple modification of the suffix array, and suffix arrays can be computed with linear time and memory. The BWT can be defined with regards to the suffix array SA of text T as (1-based indexing):
The array L stores the length of the longest common suffix of the prefixes S[1..i] and T[1..j] which end at position i and j, respectively. The variable z is used to hold the length of the longest common substring found so far. The set ret is used to hold the set of strings which are of length z.