MA Thesis - Overview

What was it on?

I wrote my MA Thesis on methods for transforming text to the conceptual graphs of John Sowa. In other words, how to automatically extract semantics from texts.

Or, how does one construct an electronic "reader" which can extract meaning from a text without assistance from humans?

I developed a method to transform a piece of Hebrew text to conceptual graphs, and wrote a program implementing the method.

What was the basic question?

The basic question was:

How can one transform a piece of text,
plus a syntactic analysis of the text,
into conceptual graphs?

I developed a method and wrote a program to do just that. The program was demonstrated to work on the first three verses of the book of Genesis, chapter 1, in the Hebrew Bible.

What was the input?

As input to my method, I had three components:

  1. The Hebrew text of Genesis 1:1-3
  2. The Werkgroep Informatica syntactic analysis of this text.
  3. An ontology that I had created in my 9th semester work.

How was it done?

The method then ran in three steps:

  1. The WI Syntactic analysis was refined, resulting in more traditional syntax trees plus some phrase-structure grammars of the text.

  2. The refined syntax trees were then transformed into conceptual graphs using rules based on the grammars produced in step 1. The rules were used for word-level and phrase-level up to just below clause-level. At clause-level, a different algorithm took over.

    The result was CGs which were "pretty good" but still not satisfactory.

  3. Finally, the CG output of step 2 was refined into fully semantic CGs with no syntax left, using rules which transformed subgraphs into more semantically adequate subgraphs.

    The final graphs was CGs which were now "rather good", being fully semantic with no syntax left.

Earlier work?

My work draws mainly on two pieces of earlier work:

  • Barriere, Caroline (1997). From a Children's First Dictionary to a Lexical Knowledge Base of Conceptual Graphs. PhD thesis, Simon Fraser University, June 1997. (Download from Barriere's website.)

  • Nicolas, Stephane, Guy W. Mineau, Bernard Moulin (2002). Extracting Conceptual Structures from English Texts Using a Lexical Ontology and a Grammatical Parser. In: Angelova, Galia, Dan Corbett and Uta Priss (eds.) Foundations and Applications of Conceptual Structures, Contributions to ICCS 2002, 10th International Conference on Conceptual Structures: Integration and Interfaces, Borovets, Bulgaria, July 15-19, 2002. Bulgarian Academy of Sciences.

Another important piece of work was Sowa and Way (1986). However, I did not use their method in my work.

  • Sowa, John F. and Eileen C. Way (1986). Implementing a semantic interpreter using conceptual graphs. In: IBM Journal of Research and Development 30(1): 57-59.

See the Bibliography in the thesis itself for more relevant references. Or check out Chapter 5, which is a survey of earlier work.