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compression techniques by simply employing
instead of IPC and PFD, other constructions.
6 CONCLUSIONS AND OPEN
PROBLEMS
We have presented a novel technique for
compressing efficiently inverted files, when storing
the document identifiers. The proposed
constructions can be harmonically combined with
other techniques that have been proposed in the
literature such as IPC and PFD and produce
compression results that are competitive and in the
majority of the cases even better than those of the
previous works. As the careful reader should have
noticed the handling of the secondary index with the
extra identifiers constitutes the main burden of our
technique. This burden can be relieved by using
more arithmetic progressions when representing
each initial inverted list, and here there exists a
tradeoff that is worth the effort to be further
explored, since it could lead to a whole set of
parametric techniques. Moreover it could be
interesting to investigate further techniques of
handling the secondary index that could lead to
faster decompression performance.
ACKNOWLEDGEMENTS
This research has been co-financed by the European
Union (European Social Fund-ESF) and Greek
national funds through the Operational Program
“Education and Lifelong Learning” of the National
Strategic Reference Framework (NSRF)-Research
Funding Program: Heracleitus II. Investing in
knowledge society through the European Social
Fund.
This research has been co-financed by the
European Union (European Social Fund-ESF) and
Greek national funds through the Operational
Program “Education and Lifelong Learning” of the
National Strategic Reference Framework (NSRF)-
Research Funding Program: Thales. Investing in
knowledge society through the European Social
Fund.
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