Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
WordNet::Similarity::rUser)Contributed Perl DocumenWordNet::Similarity::res(3)

NAME
       WordNet::Similarity::res	- Perl module for computing semantic
       relatedness of word senses using	an information content based measure
       described by Resnik (1995).

SYNOPSIS
	 use WordNet::Similarity::res;

	 use WordNet::QueryData;

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

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

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

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

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

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

DESCRIPTION
       Resnik (1995) uses the information content of concepts, computed	from
       their frequency of occurrence in	a large	corpus,	to determine the
       semantic	relatedness of word senses. This module	implements this
       measure of semantic relatedness.

       The following methods are defined:

       $res->getRelatedness ($synset1, $synset2)
	   Computes the	relatedness of two word	senses using an	information
	   content scheme.  The	relatedness is equal to	the information
	   content of the least	common subsumer	of the input synsets.

	   Parameters: two word	senses in "word#pos#sense" format.

	   Returns: Unless a problem occurs, the return	value is the
	   relatedness score.  If no path exists between the two word senses,
	   then	a large	negative number	is returned.  If an error occurs, then
	   the error level is set to non-zero and an error string is created
	   (see	the description	of getError()).	 Note: the error level will
	   also	be set to 1 and	an error string	will be	created	if no path
	   exists between the words.

   Discussion
       The relatedness value returned by the res measure is equal to the
       information content of the Least	Common Subsumer	(LCS) of the two input
       synsets.	 This means that the value will	be greater-than	or equal-to
       zero.  The upper	bound on the value is generally	quite large and	varies
       depending upon the information content file being used.	To be precise,
       the upper bound is lnA (N), where N is the sum of the frequencies of
       all the synsets in the information content files.

       The Resnick measure is sometimes	considered a "coarse" measure.	Since
       the relatedness of two synsets depends only upon	the information
       content of their	LCS, all pairs of synsets that have the	same LCS will
       have exactly the	same relatedness.  For example,	the pairs
       dog#n#1-monkey#n#1 and canine#n#1-primate#n#2.

   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 res measure, we would	have the following
       lines of	code in	the Perl program.

	  use WordNet::Similarity::res;
	  $measure = WordNet::Similarity::res->new($wn,	'/home/sid/res.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 res
       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 res
       module will have	on the first line 'WordNet::Similarity::res'. 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.	 A trace level of 1 means the
	   synsets are represented as word#pos#sense strings, while for	level
	   2, the synsets are represented as word#pos#offset strings.

       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.

       rootNode
	   The value of	this parameter indicates whether or not	a unique root
	   node	should be used.	In WordNet, there is no	unique root node for
	   the noun and	verb taxonomies. If this parameter is set to 1 (or if
	   the value is	omitted), then certain measures	(wup, path, lch, res,
	   lin,	and jcn) will "fake" a unique root node. If the	value is set
	   to 0, then no unique	root node will be used.	 If the	value is
	   omitted, then the default value, 1, is used.

       infocontent
	   The value for this parameter	should be a string that	specifies the
	   path	of an information content file containing the frequency	of
	   occurrence of every WordNet concept in a large corpus. A number of
	   utility programs are	included in this distribution that can be used
	   to generate an infocontent file (see	utils.pod).  If	no path	is
	   specified, then the default infocontent file	is used, which was
	   generated from SemCor using the sense-tags.

SEE ALSO
       perl(1),	WordNet::Similarity(3),	WordNet::QueryData(3)

       http://www.cs.utah.edu/~sidd

       http://wordnet.princeton.edu

       http://www.ai.mit.edu/~jrennie/WordNet

       http://groups.yahoo.com/group/wn-similarity

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

	 Jason Michelizzi, University of Minnesota Duluth
	 mich0212 at d.umn.edu

COPYRIGHT AND LICENSE
       Copyright (c) 2005, Ted Pedersen, Siddharth Patwardhan and Jason
       Michelizzi

       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.

perl v5.32.0			  2008-03-27	   WordNet::Similarity::res(3)

NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION FILE | SEE ALSO | AUTHORS | COPYRIGHT AND LICENSE

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=WordNet::Similarity::res&sektion=3&manpath=FreeBSD+12.1-RELEASE+and+Ports>

home | help