9,360 research outputs found
Rank, select and access in grammar-compressed strings
Given a string of length on a fixed alphabet of symbols, a
grammar compressor produces a context-free grammar of size that
generates and only . In this paper we describe data structures to
support the following operations on a grammar-compressed string:
\mbox{rank}_c(S,i) (return the number of occurrences of symbol before
position in ); \mbox{select}_c(S,i) (return the position of the th
occurrence of in ); and \mbox{access}(S,i,j) (return substring
). For rank and select we describe data structures of size
bits that support the two operations in time. We
propose another structure that uses
bits and that supports the two queries in , where
is an arbitrary constant. To our knowledge, we are the first to
study the asymptotic complexity of rank and select in the grammar-compressed
setting, and we provide a hardness result showing that significantly improving
the bounds we achieve would imply a major breakthrough on a hard
graph-theoretical problem. Our main result for access is a method that requires
bits of space and time to extract
consecutive symbols from . Alternatively, we can achieve query time using bits of space. This matches a lower bound stated by Verbin
and Yu for strings where is polynomially related to .Comment: 16 page
Implementation of an efficient Fuzzy Logic based Information Retrieval System
This paper exemplifies the implementation of an efficient Information
Retrieval (IR) System to compute the similarity between a dataset and a query
using Fuzzy Logic. TREC dataset has been used for the same purpose. The dataset
is parsed to generate keywords index which is used for the similarity
comparison with the user query. Each query is assigned a score value based on
its fuzzy similarity with the index keywords. The relevant documents are
retrieved based on the score value. The performance and accuracy of the
proposed fuzzy similarity model is compared with Cosine similarity model using
Precision-Recall curves. The results prove the dominance of Fuzzy Similarity
based IR system.Comment: arXiv admin note: substantial text overlap with
http://ntz-develop.blogspot.in/ ,
http://www.micsymposium.org/mics2012/submissions/mics2012_submission_8.pdf ,
http://www.slideshare.net/JeffreyStricklandPhD/predictive-modeling-and-analytics-selectchapters-41304405
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