NAME

WordNet::Similarity::random - Perl module for computing semantic relatedness of word senses using a random measure.

SYNOPSIS

  use WordNet::Similarity::random;

  use WordNet::QueryData;

  my $wn = WordNet::QueryData->new();

  my $random = WordNet::Similarity::random->new($wn);

  my $value = $random->getRelatedness("car#n#1", "bus#n#2");

  ($error, $errorString) = $random->getError();

  die "$errorString\n" if($error);

  print "car (sense 1) <-> bus (sense 2) = $value\n";

DESCRIPTION

This module generates random numbers as a measure of semantic relatedness of word senses. It is possible to assign a random value for a word sense pair and return the same value if the same word sense pair is passed as input. It is also possible to generate a new random value for the same word sense pair every time.

Methods

$random->setPosList()

This method is internally called to determine the parts of speech this measure is capable of dealing with.

Parameters: none.

Returns: none.

$random->initialize($file)

Overrides the initialize method in the parent class. This method essentially initializes the measure for use.

Parameters: $file -- configuration file.

Returns: none.

$random->getRelatedness ($synset1, $synset2)

Returns a value for the relatedness of the two synsets. This value is a random number greater-than or equal-to zero and less-than 'maxrand'.

If the synsets are not properly formed word#pos#sense strings, or if they are not found in WordNet, then the error level will be set to non-zero and an error string will be generated.

$random->traceOptions()

This method is internally called to determine the extra options specified by this measure (apart from the default options specified in the WordNet::Similarity base class).

Parameters: none.

Returns: none.

Usage

The semantic relatedness modules in this distribution are built as classes that define the following methods:

  new()
  getRelatedness()
  getError()
  getTraceString()

See the WordNet::Similarity(3) documentation for details of these methods.

Typical Usage Examples

To create an object of the random measure, we would have the following lines of code in the Perl program.

   use WordNet::Similarity::random;
   $measure = WordNet::Similarity::random->new($wn, '/home/sid/random.conf');

The reference of the initialized object is stored in the scalar variable '$measure'. '$wn' contains a WordNet::QueryData object that should have been created earlier in the program. The second parameter to the 'new' method is the path of the configuration file for the random measure. If the 'new' method is unable to create the object, '$measure' would be undefined. This, as well as any other error/warning may be tested.

   die "Unable to create object.\n" if(!defined $measure);
   ($err, $errString) = $measure->getError();
   die $errString."\n" if($err);

To find the semantic relatedness of the first sense of the noun 'car' and the second sense of the noun 'bus' using the measure, we would write the following piece of code:

   $relatedness = $measure->getRelatedness('car#n#1', 'bus#n#2');

To get traces for the above computation:

   print $measure->getTraceString();

However, traces must be enabled using configuration files. By default traces are turned off.

CONFIGURATION FILE

The behavior of the measures of semantic relatedness can be controlled by using configuration files. These configuration files specify how certain parameters are initialized within the object. A configuration file may be specified as a parameter during the creation of an object using the new method. The configuration files must follow a fixed format.

Every configuration file starts with the name of the module ON THE FIRST LINE of the file. For example, a configuration file for the random module will have on the first line 'WordNet::Similarity::random'. This is followed by the various parameters, each on a new line and having the form 'name::value'. The 'value' of a parameter is optional (in case of boolean parameters). In case 'value' is omitted, we would have just 'name::' on that line. Comments are supported in the configuration file. Anything following a '#' is ignored till the end of the line.

The module parses the configuration file and recognizes the following parameters:

trace: The value of this parameter specifies the level of tracing that should be employed for generating the traces. This value is an integer equal to 0, 1, or 2. If the value is omitted, then the default value, 0, is used. A value of 0 switches tracing off. A value of 1 or 2 switches tracing on, but the random measure is so simple, that generating traces makes little senses, so this option has no effect.
cache: The value of this parameter specifies whether or not caching of the relatedness values should be performed. This value is an integer equal to 0 or 1. If the value is omitted, then the default value, 1, is used. A value of 0 switches caching 'off', and a value of 1 switches caching 'on'.
maxCacheSize: The value of this parameter indicates the size of the cache, used for storing the computed relatedness value. The specified value must be a non-negative integer. If the value is omitted, then the default value, 5,000, is used. Setting maxCacheSize to zero has the same effect as setting cache to zero, but setting cache to zero is likely to be more efficient. Caching and tracing at the same time can result in excessive memory usage because the trace strings are also cached. If you intend to perform a large number of relatedness queries, then you might want to turn tracing off.
maxrand: The value of this option is the maximum random number that will be generated. The value of this option must be a positive floating-point number. The default value is 1.0. All random numbers generated will be in the range [0, maxrand).

AUTHORS

  Ted Pedersen, University of Minnesota Duluth
  tpederse at d.umn.edu

  Siddharth Patwardhan, University of Utah, Salt Lake City
  sidd at cs.utah.edu

BUGS

None.

To report a bug, go to http://groups.yahoo.com/group/wn-similarity/ or e-mail "tpederse at d.umn.edu".

COPYRIGHT AND LICENSE

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to

    The Free Software Foundation, Inc.,
    59 Temple Place - Suite 330,
    Boston, MA  02111-1307, USA.

Note: a copy of the GNU General Public License is available on the web at <http://www.gnu.org/licenses/gpl.txt> and is included in this distribution as GPL.txt.