lixiangnlp / bllip-parser

Official repository for the BLLIP reranking parser (also known as Charniak-Johnson parser, Charniak parser, Brown reranking parser) See http://pypi.python.org/pypi/bllipparser/ for Python module.

BLLIP Reranking Parser

Copyright Mark Johnson, Eugene Charniak, 24th November 2005 --- August 2006

We request acknowledgement in any publications that make use of this software and any code derived from this software. Please report the release date of the software that you are using, as this will enable others to compare their results to yours.

References:

• Charniak, Eugene, and Mark Johnson. "Coarse-to-fine n-best parsing and MaxEnt discriminative reranking." Proceedings of the 43rd Annual Meeting on Association for Computational Linguistics. Association for Computational Linguistics, 2005. http://aclweb.org/anthology/P/P05/P05-1022.pdf
• Charniak, Eugene. "A maximum-entropy-inspired parser." Proceedings of the 1st North American chapter of the Association for Computational Linguistics conference. Association for Computational Linguistics, 2000. http://aclweb.org/anthology//A/A00/A00-2018.pdf

Overview

BLLIP Parser is a statistical natural language parser including a generative constituent parser (first-stage) and discriminative maximum entropy reranker (second-stage). The latest version can be found on GitHub. This document describes basic usage of the command-line interface and describes how to build and run the reranking parser. There are now Python and Java interfaces as well. The Python interface described in README-python.rst.

Compiling the parser

1. (optional) For optimal speed, you may want to define $GCCFLAGS specifically for your machine. This step can be safely skipped as the defaults should be okay. With csh or tcsh, try something like:

   shell> setenv GCCFLAGS "-march=pentium4 -mfpmath=sse -msse2 -mmmx"
   

   or:

   shell> setenv GCCFLAGS "-march=opteron -m64"
   

2. Build the parser with:

   shell> make
   

   • Sidenote on compiling on OS X

     OS X uses the clang compiler by default which cannot currently compile the parser. Try setting this environment variable before building to change the default C++ compiler:

     shell> setenv CXX g++
     

     See http://github.com/BLLIP/bllip-parser/issues/13 for more information. Recent versions of OS X may have additional issues.

Running the parser

After it has built, the parser can be run with:

shell> parse.sh <sourcefile.txt>

For example:

shell> parse.sh sample-text/sample-data.txt

The input text must be pre-sentence segmented with each sentence in an <s> tag:

<s> Sentence 1 </s>
<s> Sentence 2 </s>
...

Note that there needs to be a space before and after the sentence.

The parser distribution currently includes a basic Penn Treebank Wall Street Journal parsing models which parse.sh will use by default. The Python interface to the parser includes a mechanism for listing and downloading additional parsing models (some of which are more accurate, depending on what you're parsing).

The script parse-eval.sh takes a list of treebank files as arguments and extracts the terminal strings from them, runs the two-stage parser on those terminal strings and then evaluates the parsing accuracy with Sparseval. For example, if the Penn Treebank 3 is installed at /usr/local/data/Penn3/, the following code evaluates the two-stage parser on section 24:

shell> parse-eval.sh /usr/local/data/Penn3/parsed/mrg/wsj/24/wsj*.mrg

The Makefile will attempt to automatically download and build Sparseval for you if you run make sparseval.

For more information on Sparseval see this paper:

@inproceedings{roark2006sparseval,
    title={SParseval: Evaluation metrics for parsing speech},
    author={Roark, Brian and Harper, Mary and Charniak, Eugene and
            Dorr, Bonnie and Johnson, Mark and Kahn, Jeremy G and
            Liu, Yang and Ostendorf, Mari and Hale, John and
            Krasnyanskaya, Anna and others},
    booktitle={Proceedings of LREC},
    year={2006}
}

We no longer distribute evalb with the parser since it sometimes skips sentences unnecessarily. Sparseval does not have these issues.

More questions?

There is more information about different components of the parser spread across README files in this distribution (see below). If you encounter a bug, please use the issue tracker. BLLIP Parser is maintained by David McClosky.

Parser details

For details on the running and training the parser, see first-stage/README. first-stage/TRAIN/README includes notes about how to retrain the parser and some information about the parser model file formats.

Reranker details

See second-stage/README for an overview. second-stage/README-retrain.rst details how to retrain the reranker. The second-stage/programs/*/README files include additional notes about different reranker components.