Linux Cubed Series 3: Developer Tools/Linux Cubed Series 3 - Developer Tools.iso/utils/text/rel-1.001

Text File | 1996-11-16 | 7.6 KB | 169 lines

From the README:

Rel is a program that determines the relevance of text documents to a
set of keywords expressed in boolean infix notation. The list of file
names that are relevant are printed to the standard output, in order
of relevance.

For example, the command:

    rel "(directory & listing)" /usr/share/man/cat1

(ie., find the relevance of all files that contain both of the words
"directory" and "listing" in the catman directory) will list 21 files,
out of the 782 catman files, (totaling 6.8 MB,) of which "ls.1" is the
fifth most relevant-meaning that to find the command that lists
directories in a Unix system, the "literature search" was cut, on
average, from 359 to 5 files, or a reduction of approximately 98%. The
command took 55 seconds to execute on a on a System V, rel. 4.2
machine, (20Mhz 386 with an 18ms. ESDI drive,) which is a considerable
expediency in relation to browsing through the files in the directory
since ls.1 is the 359'th file in the directory. Although this example
is remedial, a similar expediency can be demonstrated in searching for
documents in email repositories and text archives.

Additional applications include information robots, (ie., "mailbots,"
or "infobots,") where the disposition (ie., delivery, filing, or
viewing,) of text documents can be determined dynamically, based on
the relevance of the document to a set of criteria, framed in boolean
infix notation. Or, in other words, the program can be used to order,
or rank, text documents based on a "context," specified in a general
mathematical language, similar to that used in calculators.

General description of the program:

This program is an experiment to evaluate using infix boolean
operations as a heuristic to determine the relevance of text files in
electronic literature searches. The operators supported are, "&" for
logical "and," "|" for logical "or," and "!" for logical "not."
Parenthesis are used as grouping operators, and "partial key" searches
are fully supported, (meaning that the words can be abbreviated.) For
example, the command:

    rel "(((these & those) | (them & us)) ! we)" file1 file2 ...

would print a list of filenames that contain either the words "these"
and "those", or "them" and "us", but doesn't contain the word "we"
from the list of filenames, file1, file2, ... The order of the printed
file names is in order of relevance, where relevance is determined by
the number of incidences of the words "these", "those", "them", and
"us", in each file. The general concept is to "narrow down" the number
of files to be browsed when doing electronic literature searches for
specific words and phrases in a group of files using a command similar
to:

    more `rel "(((these & those) | (them & us)) ! we)" file1 file2`

Applicability:

Applicability of rel varies on complexity of search, size of database,
speed of host environment, etc., however, as some general guidelines:

    1) For text files with a total size of less than 5 MB, rel, and
    standard egrep(1) queries of the text files will probably prove
    adequate.

    2) For text files with a total size of 5 MB to 50 MB, qt seems
    adequate for most queries. The significant issue is that, although
    the retrieval execution times are probably adequate with qt, the
    database write times are not impressive. Qt is listed in "Related
    information retrieval software:," below.

    3) For text files with a total size that is larger than 50 MB, or
    where concurrency is an issue, it would be appropriate to consider
    one of the other alternatives listed in "Related information
    retrieval software:," below.

Extensibility:

    The source was written with extensibility as an issue. To alter
    character transliterations, see uppercase.c for details. For
    enhancements to phrase searching and hyphenation suggestions, see
    translit.c.

    It is possible to "weight" the relevance determination of
    documents that are composed in one of the standardized general
    markup languages, like TeX/LaTeX, or SGML. The "weight" of the
    relevance of search matches depends on where the words are found
    in the structure of the document, for example, if the search was
    for "numerical" and "methods," \chapter{Numerical Methods} would
    be weighted "stronger" than if the words were found in
    \section{Numerical Methods}, which in turn would be weighted
    "stronger" than if the words were found in a paragraph. This would
    permit relevance of a document to be determined by how author
    structured the document. See eval.c for suggestions.

    The list of identifiers in the search argument can be printed to
    stdio, possibly preceeded by a '+' character and separated by '|'
    characters to make an egrep(1) compatible search argument, which
    could, conceivably, be used as the search argument in a browser so
    that something like:

       "browse `rel arg directory'"

    would automatically search the directory for arg, load the files
    into the browser, and skip to the first instance of an identifier,
    with one button scanning to the next instance, and so on. See
    postfix.c for suggestions.

    The source architecture is very modularized to facilitate adapting
    the program to different environments and applications, for
    example, a "mailbot" can be constructed by eliminating
    searchpath.c, and constructing a list of postfix stacks, with
    perhaps an email address element added to each postfix stack, in
    such a manner that the program could be used to scan incoming
    mail, and if the mail was relevant to any postfix criteria, it
    would be forwarded to the recipient.

    The program is capable of running as a wide area, distributed,
    full text information retrieval system. A possible scenario would
    be to distribute a large database in many systems that are
    internetworked together, presumably via the Unix inet facility,
    with each system running a copy of the program. Queries would be
    submitted to the systems, and the systems would return individual
    records containing the count of matches to the query, and the file
    name containing the matches, perhaps with the machine name, in
    such a manner that the records could be sorted on the "count
    field," and a network wide "browser" could be used to view the
    documents, or a script could be made to use the "r suite" to
    transfer the documents into the local machine. Obviously, the
    queries would be run in parallel on the machines in the
    network-concurrency would not be an issue. See the function,
    main(), below, for suggestions.

References:

    1) "Information Retrieval, Data Structures & Algorithms," William
    B. Frakes, Ricardo Baeza-Yates, Editors, Prentice Hall, Englewood
    Cliffs, New Jersey 07632, 1992, ISBN 0-13-463837-9.

    The sources for the many of the algorithms presented in 1) are
    available by ftp, ftp.vt.edu:/pub/reuse/ircode.tar.Z

    2) "Text Information Retrieval Systems," Charles T. Meadow,
    Academic Press, Inc, San Diego, 1992, ISBN 0-12-487410-X.

    3) "Full Text Databases," Carol Tenopir, Jung Soon Ro, Greenwood
    Press, New York, 1990, ISBN 0-313-26303-5.

    4) "Text and Context, Document Processing and Storage," Susan
    Jones, Springer-Verlag, New York, 1991, ISBN 0-387-19604-8.

    5) ftp think.com:/wais/wais-corporate-paper.text

    6) ftp cs.toronto.edu:/pub/lq-text.README.1.10

Related information retrieval software:

    1) Wais, available by ftp, think.com:/wais/wais-8-b5.1.tar.Z.

    2) Lq-text, available by ftp,
    cs.toronto.edu:/pub/lq-text1.10.tar.Z.

    3) Qt, available by ftp,
    ftp.uu.net:/usenet/comp.sources/unix/volume27.

[e-mail] (John Conover)
Campbell, California, USA
September, 1995