Overview

ERMA is a software package that implements general CRFs (and MRFs) with no restriction to the model structure. The package includes a training algorithm that performs Empirical Risk Minimization under Approximations (ERMA) as described here and here. ERMA can optimize several loss functions such as Accuracy, MSE and F-score.

Features

• Unrestricted model structure.
• Loss-aware and approximation-aware minimum-risk training via Empirical Risk Minimization under Approximations (ERMA).
• A syntax for specifying model structure.
• Implemented in Java: easy to port to different architectures.
• Generic and easily extensible.

Citations

If you use ERMA for research purposes, please cite:

@InProceedings{stoyanov-ropson-eisner-2011,
  author =      {Veselin Stoyanov and Alexander Ropson and Jason
	     Eisner},
  title =       {Empirical Risk Minimization of Graphical Model
	     Parameters Given Approximate Inference, Decoding, and
	     Model Structure},
  booktitle =   {Proceedings of the 14th International Conference on
	     Artificial Intelligence and Statistics (AISTATS)},
  series =      {JMLR Workshop and Conference Proceedings},
  volume =      {15},
  pages =       {725--733},
  note =        {Supplementary material (4 pages) also available},
  year =        {2011},
  month =       apr,
  address =     {Fort Lauderdale},
  url =         {http://cs.jhu.edu/~jason/papers/#stoyanov-ropson-eisner-2011}
}

or

@InProceedings{stoyanov-eisner-2012-naacl,
  author =      {Veselin Stoyanov and Jason Eisner},
  title =       {Minimum-Risk Training of Approximate {CRF}-Based {NLP}
	     Systems},
  booktitle =   {Proceedings of NAACL-HLT},
  pages =       {120--130},
  year =        {2012},
  month =       jun,
  address =     {Montreal},
  url =         {http://cs.jhu.edu/~jason/papers/#stoyanov-eisner-2012-naacl}
}

BUILD

To build the project:

mvn compile

To create Eclipse project files:

mvn eclipse:eclipse

The above command will add the .project and .classpath files with the M2_REPO classpath variable. In Eclipse open the Preferences and navigate to 'Java --> Build Path --> Classpath Variables'. Add a new classpath variable M2_REPO with the path to your local repository (e.g. ~/.m2/repository).

To build a single jar with all the dependencies included:

mvn compile assembly:single

TUTORIAL

To follow the tutorial example from the ERMA website (https://sites.google.com/site/ermasoftware/getting-started), run the following commands:

# Create a new directory with all the appropriate files.
mkdir tmp
export TUTORIAL=src/main/resources/tutorial
export CONFIG=src/main/config/toy.cfg
cp -r src/main/resources/tutorial tmp/tutorial
cp -r src/main/config tmp/config
# Run the commands within that directory using the jar in the target directory.
cd tmp    
python ../src/main/python/txt2ff.py tutorial/toy.train.txt
java -cp ../target/erma-1.0.1-SNAPSHOT-jar-with-dependencies.jar driver.Learner -config=config/toy.cfg
java -cp ../target/erma-1.0.1-SNAPSHOT-jar-with-dependencies.jar driver.Tester -config=config/toy.cfg -data=tutorial/toy.test.data.ff -features=tutorial/toy.trained-best.ff
java -cp ../target/erma-1.0.1-SNAPSHOT-jar-with-dependencies.jar driver.Classifier -config=config/toy.cfg -data=tutorial/toy.test.data.ff -features=tutorial/toy.trained-best.ff -pred_fname=tutorial/toy.test.data.predictions