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README

               Link Grammar Parser - Patched Version
               -------------------------------------
                       Version 4.3.5

This directory contains a *patched* version of the final original 
release of the Link Grammar Parser.  It has been patched to fix a 
few bugs, add a few enhancements, and, in general, make the Link 
Grammar Parser easier to use. This version includes Java bindings.

It is released under the BSD license (which is GPL compatible), 
making it freely available for private and commercial use, with 
few restrictions.  The terms of the license are given in the 
LICENSE file included with this software, and also available at 
http://www.link.cs.cmu.edu/link/license.html.

Please see the web page http://www.abisource.com/projects/link-grammar/
for more information.  The original website, including documentation,
is located at http://www.link.cs.cmu.edu/link 

CONTENTS of this directory:

   LICENSE                  The license describing terms of use

   link-grammar/*.c         The program.  (Written in ANSI-C)
   
   data/en/4.0.dict         The file containing the dictionary definitions.

   data/en/4.0.knowledge    The post-processing knowledge file.

   data/en/4.0.constituents The constituent knowledge file.

   data/en/4.0.affix        The affix file.

   data/en/tiny.dict        A small sample dictionary.

   data/en/words/*          A directory full of word lists.

   data/en/4.0.batch        This is a batch file of sentences (both grammatical
                            and ungrammatical ones) that are handled correctly
                            by this release of the system.  Feed this into the
                            parser with "./link-parser < 4.0.batch"

   configure                The GNU configuration script

UNPACKING and signature verification:

   The system is distributed using the normal tar.gz format; it can be
   extracted using the "tar -zxf link-grammar.tar.gz" command at the
   command line.

   The files have been digitally signed to make sure that there was no 
   corruption of the dataset during download, and to help ensure that
   no malicious changes were made to the code internals by third
   parties. The signatures can be checked with the gpg command:

   gpg --verify link-grammar-4.3.5.tar.gz.asc

   which should generate output identical to (except for the date):

   gpg: Signature made Tue Feb 26 19:41:07 2008 CST using RSA key ID C0389241
   gpg: Good signature from "Linas Vepstas (current active email; others are inactive) <linasvepstas@gmail.com>"

   Alternately, the md5 checksums can be verified. These do not provide
   cryptographic security, but they can detect simple corruption. To
   verify the checksums, issue "md5sum -c MD5SUM" at the command line.

CREATING the system:

   To compile the link-grammar shared library and demonstration program, 
   at the command line, type:

        ./configure
        make

   To install, change user to "root" and say

        make install

   This will install the lib-link-grammar.so library into /usr/local/lib
   the header files in /usr/local/include/link-grammar
   and the dictionaries into /usr/local/share/link-grammar.

   The /usr/local install target can be over-ridden using the 
   standard GNU configure --prefix option, so for example:

      ./configure --prefix=/opt/link-grammar

	By using pkg-config (see below), non-standard install locations
	can be automatically detected.

   The system has been tested and works well on 32 and 64-bit Linux
   systems, as well as on many Microsoft Windows systems, under the
   CYGWIN development environment.

   Windows users may need to also do the following:

gcc -shared -Wall -D_JNI_IMPLEMENTATION_ -Wl,--kill-at .libs/analyze-linkage.o .libs/and.o .libs/api.o .libs/build-disjuncts.o
.libs/command-line.o .libs/constituents.o .libs/count.o .libs/error.o .libs/extract-links.o .libs/fast-match.o .libs/idiom.o
.libs/linkset.o .libs/massage.o .libs/post-process.o .libs/pp_knowledge.o .libs/pp_lexer.o .libs/pp_linkset.o .libs/preparation.o
.libs/print.o .libs/print-util.o .libs/prune.o .libs/read-dict.o .libs/resources.o .libs/string-set.o .libs/tokenize.o
.libs/utilities.o .libs/word-file.o .libs/word-utils.o .libs/prefix.o -o /usr/local/bin/link-grammar.dll

gcc -shared -Wall -D_JNI_IMPLEMENTATION_ -Wl,--kill-at .libs/jni-client.o  /usr/local/bin/link-grammar.dll -o
/usr/local/bin/link-grammar-java.dll

RUNNING the program:

   To run the program issue the Unix command:

       ./link-parser

   This starts the program.  Help is available there with "!help".  A
   number of user-settable variables control what happens.  "!var" shows
   these variables and their current values.

   The program can run in batch mode for testing the system on a large
   number of sentences.  The following command runs the parser on
   a file called 4.0.batch

       ./link-parser < 4.0.batch

   The line "!batch" near the top of 4.0.batch turns on batch mode.  In
   this mode sentences labeled with an initial "*" should be rejected
   and those not starting with a "*" should be accepted.  Any deviation
   from this behavior is reported as an error.

USING the parser in your own applications:

   There is a API (application program interface) to the parser.  This
   makes it easy to incorporate it into your own applications.  The API
   documented on the web site.

USING pkg-config:

	To make compiling and linking easier, the current release uses 
	the pkg-config system. To determine the location of the link-grammar
	header files, say `pkg-config --cflags link-grammar`  To obtain
	the location of the libraries, say `pkg-config --libs link-grammar`
	Thus, for example, a typical makefile might include the targets:

	.c.o:
   	cc -O2 -g -Wall -c $< `pkg-config --cflags link-grammar`

	$(EXE): $(OBJS)
   	cc -g -o $@ $^ `pkg-config --libs link-grammar`

JAVA bindings:

   This release includes a very simple Java binding.  Its use is optional. 
   It can be accessed by copying the file LinkGrammar.java into your java
   project.  Alternately, "ant" can be used, with the build.xml file, to 
   build the appropriate jar file.

   The bindings will be built automatically if jni.h can be found.  
   Some common java JVM distributions (most notably, the ones from Sun) 
   place this file in unusual locations, where it cannot be found. 
   To remedy this, specify the location with the CPPFLAGS variable: 
   so, for example,

      export CPPFLAGS="-I/opt/jdk1.5/include/:/opt/jdk1.5/include/linux"
   or
      export CPPFLAGS="-I/c/java/jdk1.6.0/include/ -I/c/java/jdk1.6.0/include/win32/"

   Please note that the use of /opt is non-standard, and most system
   tools will fail to find packages installed there.

COMMERCIAL use:

   The original authors would be pleased to discuss alternate 
   licensing terms and/or additional research work, with those 
   wanting to use this system under a paid contract.

   Academic products or papers should reference the various
   link grammar publications.

ADDRESSES

   If you have any questions, or find any bugs, please feel free 
   to send a note to the mailing list:

      link-grammar@googlegroups.com 

   Although all messages should go to the mailing list, the current
   maintainers can be contacted at:

     Dom Lachowicz - <domlachowicz@gmail.com>
     Linas Vepstas - <linasvepstas@gmail.com>

   The original authors of the Link Grammar parser are:

     Daniel Sleator                    sleator@cs.cmu.edu  
     Computer Science Department       412-268-7563
     Carnegie Mellon University        www.cs.cmu.edu/~sleator
     Pittsburgh, PA 15213              

     Davy Temperley                    dtemp@theory.esm.rochester.edu
     Eastman School of Music           716-274-1557
     26 Gibbs St.                      www.link.cs.cmu.edu/temperley
     Rochester, NY 14604

     John Lafferty                     lafferty@cs.cmu.edu
     Computer Science Department       412-268-6791
     Carnegie Mellon University        www.cs.cmu.edu/~lafferty
     Pittsburgh, PA 15213              


TODO:
   Some working notes.
	read-dict.c: after running insert_dict() to create dictionary tree,
      the tree is highly unbalanced, and should be rebalanced before use.
      This would provide a minor performance improvement.

   tokenize.c: build_sentence_expressions() contains some 
      English-language-specific morphology guessing.  This should be 
      refactored out, as it doesn't really apply to non-English
      languages.

   no-links-cross: Link Grammar uses a constraint that al linakges must
      be planar graphs. While this is mostly correct, it would probably 
      be more correct to use "landmark transitivity" as articulated by
      Hudson in the Word Grammar theory.  This might allow the elimination
      of most or all post-processing rules.

      This is done by making each link directional: one end of the link
      is the parent. (e.g. noun, noun-modifier: the noun is the parent).
      Parents are landmarks for children.  Transitivity is applied to 
      parent-child relationships. Specifically, the no-links-cross
      rule is replaced by two landmark transitivity rules:

      -- If B is a landmark for C, then  A is also a type-L landmark for C
      -- If A is a landmark for C, then B is also a landmark for C

      where type-L means either a right-going or left-going link.

     See http://goertzel.org/ProwlGrammar.pdf for details.

  "to be fishing": Link grammar offers four parses of "I was fishing for
     evidence", two of which are given low scores, and two are given
     high scores. Of the two with high scores, one parse is clearly bad.
     Its links "to be fishing.noun" as opposed to the correct 
     "to be fishing.gerund". That is, I can be happy, healthy and wise,
     but I certainly cannot be fishing.noun.  This is perhaps not
     just a bug in the structure of the dictionary, but is perhaps 
     deeper: link-grammar has little or no concept of lexical units
     (i.e. collocations, idioms, institutional phrases), which thus
     allows parses with bad word-senses to sneak in.

     The goal is to introduce more knowledge of lexical units into LG.

  incremental parsing: to avoid a combinatorial explosion of parses,
    it would be nice to have an incremental parsing, phrase by phrase,
    using a Viterbi-like algorithm to obtain the parse. Thus, for example,
    the parse of the last half of a long, run-on sentence should not be
    sensitive to the parse of the begining of the sentence. 

    Doing so would help with combinatorial explosion. So, for example,
    if the first half of a sentence has 4 plausible parses, and the
    last half has 4 more, then link-grammar reports 16 parses total.
    It would be much, much more useful to instead be given the 
    factored results: i.e. the for plausbile parses for the 
    first half, and the four plausible parses for the last half.
    The lower combinatoric stress would ease the burden on 
    downstream users of link-grammar.

    (This somewhat resembles the application of construction grammar
    ideas to the link-grammar dictionary).