OWL-Time is an ontology for describing the temporal content of Web pages and the temporal properties of Web Services.

• Feng Pan. 2007. Representing Complex Temporal Phenomena for the Semantic Web and Natural Language. Ph.D. Thesis. Computer Science Department, University of Sothern California.

• Jerry R. Hobbs and Feng Pan. 2004. An Ontology of Time for the Semantic Web. ACM Transactions on Asian Language Processing (TALIP): Special issue on Temporal Information Processing, Vol. 3, No. 1, March 2004, pp. 66-85.

• Documentation (with axioms in first-order logic) of OWL-Time.

W3C notes on the time ontology and the time zone resource in OWL:

• Jerry R. Hobbs and Feng Pan. 2006. Time Ontology in OWL. Ontology Engineering Patterns Task Force of the Semantic Web Best Practices and Deployment Working Group, World Wide Web Consortium (W3C) notes. (http://www.w3.org/TR/owl-time/)

The publications on Temporal Aggregates (first one focuses on the first-order logic representation, embedding iCalendar recurrence sets, and natural language examples, while the second one focuses on the OWL representation of the ontology):

• Feng Pan and Jerry R. Hobbs. 2005. Temporal Aggregates in OWL-Time. In Proceedings of the 18th International Florida Artificial Intelligence Research Society Conference (FLAIRS-2005), Clearwater Beach, Florida, pp. 560-565, AAAI Press.

• Feng Pan. 2005. A Temporal Aggregates Ontology in OWL for the Semantic Web. In Proceedings of the AAAI Fall Symposium on Agents and the Semantic Web, Arlington, Virginia, 2005.

There is an "entry" sub-ontology of time in OWL, which is simpler than the full OWL-Time and provides most of the basic temporal concepts and relations that most simple applications would need, i.e., a vocabulary for expressing facts about topological relations among instants, intervals, and events, together with information about durations, and about dates and times. It allows temporal predicates to apply directly to events.

• Encodings of the ontology in OWL. (time-entry.owl)

• Encodings of the use case in OWL. (time-entry-case1.owl)

• A paper describing this sub-ontology and how it can be used in OWL-S:
  Feng Pan and Jerry R. Hobbs. 2004. Time in OWL-S. In Proceedings of the AAAI Spring Symposium on Semantic Web Services, Stanford University, CA, pp. 29-36, 2004.

A time zone resource in OWL for the entire world.

Other related resources:

• A paper describing the relation between OWL-Time and TimeML(a mark-up language for annotating temporal information in text):
  Jerry R. Hobbs and James Pustejovsky. 2003. Annotating and Reasoning about Time and Events. In Proceedings of the AAAI Spring Symposium on Logical Formulization of Commonsense Reasoning, Stanford University, CA, 2003.

• Ian Niles' Table of correspondences between SUMO and OWL-Time.

• The old DAML-Time homepage contains a program that automatically converts the axioms into a Lisp-like representation which is more or less a subset of KIF, and the KIF/Lisp version of axioms in OWL-Time.