ADAPT CENTRE participation to the shared task on Verbal Multiword Expressions 2017 (VMWE17)

Authors: Alfredo Maldonado, Lifeng Han, Erwan Moreau, Ashjan Alsulaimani, Koel Dutta Chowdhury, Carl Vogel and Qun Liu.

Links

• Shared task website
• Shared Task data (gitlab)
• Our paper
• Reference data (1.8 GB) (remark: it's normal that the preview doesn't work, simply click on the download link)
  • For most of the VMWE17 languages, contains several version of Europarl which can be used as "reference corpus" with the semantic reranker.
  • Uncompress with tar xfj reference-data.tar.bz2

Requirements

• CRF++ must be installed and accessible via PATH
• The shared task data can be downloaded or cloned from https://gitlab.com/parseme/sharedtask-data
• pre-tokenized Europarl data to be used as reference data can be downloaded from the link above

Remark: Weka is included in the repository.

Installation

From the main directory run:

source setup-path.sh

This will compile the code if needed and add the relevant directories to PATH. You can add this to your .bashrc file in order to have the PATH set up whenever you open a new session.

Usage

Simple training + testing

From the main directory:

run-config-train-test.sh -l sharedtask-data/1.0/FR -a sharedtask-data/1.0/FR conf/default.conf crf/templates/ reference-data/FR/ model output

• -l (learn) for training using the training data provided in the directory
• -a (apply) for testing using the test data provided in the directory
• using configuration file conf/default.conf
• reference-data contains the reference data (see link above)
• model will contain the model at the end of the process
• output is the "work directory"; at the end of the testing process it contains:
  • The predictions in parsemetsv format are stored in <work dir>/output.parsemetsv
  • Evaluation results are stored in <work dir>/test-eval.out.

Reproducing the results from the paper

Requires the reference data downloaded from the link given at the begining of this document. From the main directory:

# Generate the set of config files
mkdir -p experiments/configs; echo conf/vary-templates-and-refcorpus.conf | expand-multi-config.pl -p experiments/configs/ >configs.list
# Generate the tasks to run
generate-tasks.sh sharedtask-data/1.0/ configs.list crf/templates/ reference-data/ experiments/cv >tasks
# split to run 10 processes in parallel
split -d -l 18 tasks batch.
# run 
for f in batch.*; do (bash $f &); done

• See "Configuration files" below for explanations about the generation of the config files with expand-multi-config.pl.
• generate-tasks.sh creates directories and writes the list of commands to run.
• The last two lines show a simple way to split the processes into 10 batches to run in parallel; the full process can take around 24 hours.
• Some of the configurations will not work with some of the datasets (conllu data or Europarl data not available; see readme in the reference data archive - link at the beginning of this document).
• The results from a large experiment with multiple config files like the above can be collected conveniently as a TSV table: ls experiments/cv/*/*/test-eval.out | collect-results.pl experiments/configs/ results.tsv
• Option -c can be used with generate-tasks.sh to perform cross-validation on the training set instead of using the training and test set.

Details

Configuration files

The scripts are meant to be used with configuration files which contain values for the parameters. Examples can be found in the directory conf. Additionally, a batch of configuration files can be generated using e.g.:

# caution: generates almost 2 millions config files
mkdir configs; echo conf/options.multi-conf | expand-multi-config.pl configs/ 

In order to generate a different set of configurations, either customize the values that a parameter can take in conf/options.multi-conf or use the -r option to generate a random subset of config files, e.g.:

# generate a random 50 config files
mkdir configs; echo conf/options.multi-conf | expand-multi-config.pl -r 50 configs/ 

Reference data

• Reference data, including pre-tokenized Europarl corpus for most languages, can be downloaded from the link given at the start of this document.
• In order to use the training set as reference data, set refCorpus=train.conllu in the config file and specify the input directory containing the shared task data as "reference data dir".
  • Remark: refCorpus=train.conllu:lemma will make the system use the lemma column instead of the token column.
• In order to use only the CRF component (no semantic reranker), set refCorpus=NONE in the config file.

semantic-reranker/context-features-code

This is the C++ code which extracts the features for the semantic reranking. The semantic reranker consists of two main steps: feature extraction and supervised learning. The former produces features for each of the 10 candidate labelings provided by the CRF component for every sentence. The latter trains or applies a Weka model using said features; the model is meant to score every candidate, so that the highest score can be selected as the best prediction.

Remark: this behaviour means that the reranker has to be trained on (top 10) data predicted by the CRF++ component. Therefore the training stage requires to cross-validation by CRF++, in order to obtain realistic top 10 predictions on the training set.

• Training
  • context-features-train produces the features, together with the gold label for every candidate labeling;
  • Weka is used to train a supervised regression model based on these features.
• Testing
  • context-features-test produces the features for every candidate labeling;
  • Weka predicts a score based on these features for every candidate labeling;
  • For every sentence, the candidate which obtains the highest score among the 10 possible labelings is selected.

An additional executable single-expr-features can be used to generate a subset of the features (called internal features) for a single expression given as a parameter. This executable is used only for debugging or inspection purposes. Example:

single-expr-features reference-data/FR/europarl-v7.generic.tok rendre compte