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REPRESENTING COMPLEX TEMPORAL PHENOMENA FOR THE SEMANTIC
WEB AND NATURAL LANGUAGE
by
Feng Pan
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(COMPUTER SCIENCE)
December 2007
Copyright 2007 Feng Pan
Object Description
| Title | Representing complex temporal phenomena for the semantic web and natural language |
| Author | Pan, Feng |
| Author email | fpan@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Computer Science |
| School | Viterbi School of Engineering |
| Date defended/completed | 2007-09-05 |
| Date submitted | 2007 |
| Restricted until | Unrestricted |
| Date published | 2007-10-02 |
| Advisor (committee chair) | Hobbs, Jerry R. |
| Advisor (committee member) |
Chalupsky, Hans Knight, Kevin Rosenbloom, Paul O'Leary, Daniel |
| Abstract | As an essential dimension of our information space, time plays a very important role in every aspect of our lives. A specification of temporal information is necessarily required for a large group of applications, including the Semantic Web and natural language. In response to this need, we have developed a rich ontology of temporal concepts, OWL-Time (formerly DAML-Time), for describing the temporal content of Web pages and the temporal properties of Web services. Since most of the information on the Web is in natural language, it can also be used for temporal reasoning and to increase the temporal awareness for different natural language applications. The ontology is represented in first-order logic (FOL) and the OWL Web Ontology Language.; The ontology covers a very rich set of temporal concepts. It extends Hobbs (2002)'s work with more complex temporal phenomena, such as temporal aggregates, temporal arithmetic mixing months and days, and vague event durations. We have also created axioms that map subsets of the problems that can be represented by the ontology in FOL to temporal constraint-based formalisms for more efficient temporal reasoning. The temporal aggregate part of the ontology is rich enough to handle both complex multiple-layered and conditional temporal aggregates. A systematic way of mapping recurrence sets in iCalendar (iCal) to temporal aggregates in OWL-Time was developed to give it access to the full ontology of time for temporal reasoning. A set of rules for temporal arithmetic mixing months and days were developed with consideration of different desired arithmetic properties, such as commutativity and associativity.; Since missing explicit and exact durations is one of the most common sources of incomplete information for temporal reasoning in natural language applications, we have constructed an annotated corpus to extract the implicit and vague event durations from text. We generated annotation guidelines, categorized the event classes to reduce gross discrepancies in inter-annotator judgments, used normal distributions to model event duration annotations that are intervals on a scale and to measure their inter-annotator agreement. Machine learning techniques were then applied to the annotated data and produced coarse-grained event duration information automatically, considerably outperforming a baseline and approaching human performance. The methods used here should be applicable to other kinds of vague but substantive information. |
| Keyword | knowledge representation; temporal reasoning; semantic web; natural language processing |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Type | texts |
| Legacy record ID | usctheses-m837 |
| Rights | Pan, Feng |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Pan-20071002 |
| Archival file | uscthesesreloadpub_Volume51/etd-Pan-20071002.pdf |
Description
| Title | Page 1 |
| Full text | REPRESENTING COMPLEX TEMPORAL PHENOMENA FOR THE SEMANTIC WEB AND NATURAL LANGUAGE by Feng Pan A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (COMPUTER SCIENCE) December 2007 Copyright 2007 Feng Pan |
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