nlsparql-wfst

The goal of the project is to develop Spoken Language Understanding (SLU) Module for Movie Domain using NL-SPARQL Dataset.

Data Analysis

Some previous data analysis on the dataset has been done. In the data-analysis folder some scripts can be found.

• concept-distribution.py has been used to look at the concept distribution in a fast way to find insights
• oov.py has been used to calculate the percentage of out-of-vocabulary concepts
• zipf.py has been used to test the Zipf's law Note: the results of concept-distribution are stored into a csv file called results.csv. It is due to the fact that create a readable graph with matplotlib can be difficult and doing it with Excel or Numbers or whatever is easier and faster

Models

Two models have been developed: a basic model that ---- and an advanced model that ----. The model is automatically selected by main.py. To run the basic model, three parameters are needed:

1. the feature. It varies among 'word','pos','lemma'
2. the ngram order. An integer number
3. the ngram method. It varies among 'witten_bell','absolute','katz','kneser_ney','presmoothed','unsmoothed'

To run the advanced model, four parameters are needed:

1. the feature. It varies among 'word','pos','lemma'
2. the ngram order. An integer number
3. the ngram method. It varies among 'witten_bell','absolute','katz','kneser_ney','presmoothed','unsmoothed'
4. the advanced feature. It varies among 'word','pos','lemma'

To run the basic model, open a console, cd to wfst and launch

python main.py <feature> <ngram-order> <method>

for the basic model or

python main.py <feature> <ngram-order> <method> <advanced_feature>

for the advanced model.

Dataset

The dataset can be found in wfst/dataset.

There are two training files and two testing files. The files named *.data have been annotated using the [IOB notation](https://en.wikipedia.org/wiki/Inside–outside–beginning_(tagging). The others (*.feats.txt) contain a tuple formed by the concept, the POS-tag, the lemma.

Modules

The project is composed of the main file written in python and some other files which are shell scripts.

main.py

It is the entry point. Once the user runs this script, all the other files are called using os.system. Three parameters must be passed to the script:

1. the feature. It varies among 'word','pos','lemma'
2. the ngram order. An integer number
3. the ngram method. It varies among 'witten_bell','absolute','katz','kneser_ney','presmoothed','unsmoothed'
4. the advanced feature (optional). It varies among 'word','pos','lemma' The pipeline followed by main.py is this:

file_generator.sh

it creates two temp files: train.base and test.base. Both contain the following information separated by \s:

• concept
• POS-tag
• lemma
• IOB-tag
• IOB-tag "-" concept
• IOB-tag "-" POS-tag
• IOB-tag "-" lemma

lexicon_generator.sh

using ngramsymbols, two temp files are generated: concept.lex (concept lexicon) and feature.lex (feature lexicon)

counter.sh

To compute the weights (probabilities) of the final-state transducer concept instances, feature instances and <concept, feature> instances must be countered. This file takes care of this and it saves the results into three temp files:

• feature_counter.txt
• concept_counter.txt
• feature_concept_counter.txt Most of the code in this file has been provided by Evgeny Stepanov, Ph.D.

unknown.sh

Between the end of the execution of counter.sh and the beginning of this script, main.py takes care of generating an openfst-compatible file in order to generate the transducer. For simplicity, unknown.sh add some lines to the file generated by main.py concerning the OOV concepts.

logic.sh

It uses the openfst library to create the transducer.

results.sh

It generates a file which is compatible with conlleval.pl

Once the results are computed, the evaluation is stored in a file called < feature >_< ngramorder >_< ngrammethod >.txt that can be found in wfst/results. Finally, it removes all the unecessary files