Semantic Parser

Semantic parser is used to translate text representation into formal language representation. The aim is to be able to process user utterances and react upon them.

roboy_parser is based on SEMPRE <http://nlp.stanford.edu/software/sempre/>. It is currently being modified to fulfill Roboy Dialog system needs.

Installation

In order to use semantic parser, you need to:

  • clone roboy_parser repository:

    git clone http://github.com/Roboy/roboy_parser

  • navigate to created repository:

    cd roboy_parser

  • download dependencies:

    ./pull-dependencies roboy

  • build it:

    mvn clean
mvn install

  • run it:

    mvn exec:java -Dexec.mainClass=edu.stanford.nlp.sempre.Main

Architecture

Semantic parser is based on the language model and NLP algorithms that then apply rules to the utterance to translate it. Language model consists of: - set of grammar rules, - lexicon, - training dataset.

General architecture can be seen on the diagram below.

../_images/parser.png
alt:Semantic parser general architecture

Implementation

roboy_parser is a separate Java project and is communicating using WebSocket. Dialog system has a client implemented in SemanticParserAnalyzer.java class. It is therefore part of Natural Language Understanding unit.

Current parser was modified from SEMPRE and currently has following components

../_images/PARSER_arch.png
alt:Semantic parser components

Functionalities

Roboy parser currently has currently following functionalities:

Semantic Parser algorithms used
Functionality Software used Summary
Tokens OpenNLP Tokenized utterance
POS Tags OpenNLP Tagging tokens as part of speech
NER Tags OpenNLP Tool used to tag named entities like PERSON, NUMBER, ORGANIZATION
Triple extraction OpenIE Tool used to extract triples from sentences in form (Subject,Predicate,Object)
Parser result Parser Logical representation of an utterance
Parser answer Parser Answer for resulting parser result
Follow-up Parser Follow-up questions for underspecified term

Usage

In order to run the parser, you need to run roboy_parser first - see instructions on project Github <http://github.com/Roboy/roboy_parser> and then run Dialog System.

Configurations

To test parser, you can run following execution configurations using maven. For more information refer to project documentation <http://github.com/Roboy/roboy_parser>

Possible parser configurations
Command Options
interactive Standard lexicon and grammar, communication over terminal. Does not load all the models ahead. Error retrieval enabled.
demo-error Standard lexicon and grammar, communication over socket. Loads all the models ahead. Error retrieval enabled
demo Standard lexicon and grammar, communication over socket. Loads all the models ahead. Error retrieval disabled
debug Standard lexicon and grammar, communication over server (web page available). Does not load all the models ahead. Error retrieval enabled