55 research outputs found
LRM-Trees: Compressed Indices, Adaptive Sorting, and Compressed Permutations
LRM-Trees are an elegant way to partition a sequence of values into sorted
consecutive blocks, and to express the relative position of the first element
of each block within a previous block. They were used to encode ordinal trees
and to index integer arrays in order to support range minimum queries on them.
We describe how they yield many other convenient results in a variety of areas,
from data structures to algorithms: some compressed succinct indices for range
minimum queries; a new adaptive sorting algorithm; and a compressed succinct
data structure for permutations supporting direct and indirect application in
time all the shortest as the permutation is compressible.Comment: 13 pages, 1 figur
Compressed Representations of Permutations, and Applications
We explore various techniques to compress a permutation over n
integers, taking advantage of ordered subsequences in , while supporting
its application (i) and the application of its inverse in
small time. Our compression schemes yield several interesting byproducts, in
many cases matching, improving or extending the best existing results on
applications such as the encoding of a permutation in order to support iterated
applications of it, of integer functions, and of inverted lists and
suffix arrays
Compact Binary Relation Representations with Rich Functionality
Binary relations are an important abstraction arising in many data
representation problems. The data structures proposed so far to represent them
support just a few basic operations required to fit one particular application.
We identify many of those operations arising in applications and generalize
them into a wide set of desirable queries for a binary relation representation.
We also identify reductions among those operations. We then introduce several
novel binary relation representations, some simple and some quite
sophisticated, that not only are space-efficient but also efficiently support a
large subset of the desired queries.Comment: 32 page
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