DAML-Time Homepage

This page provides documents and resources from the DAML-Time effort, part of the DARPA Agent Markup Language project.

These resources are provided for research purposes and without any guarantees of safety or correctness. I hope you find them useful.

Please report problems or send suggestions to ferguson@cs.rochester.edu.

A DAML Ontology of Time

This collaborative project, led by Jerry Hobbs, aims to develop a representative ontology of time that expresses temporal concepts and properties common to any formalization of time. The ontology is formulated as a set of first-order predicate calculus axioms. These axioms can be used as-is, or can be specialized to describe other, more specific, temporal theories. In several places ontological choices must be made. These are clearly indicated in the text and result in optional axioms that might or might not be part of any specific temporal ontology.

We have developed tools to automatically convert the axioms into a Lisp-like representation which is more or less a subset of KIF.

We have developed tools for automatically converting KIF (at least, the subset of KIF used in the axioms) into DAML, using the encoding described in A Proposal for Encoding Logic in RDF/DAML by McDermott, et al.

NOTE: The DRS encoding does not specify how to translate the unary predicate used in the current version of the DAML-Time axioms. Until this is resolved, the DAML version of the axioms cannot be generated.

Feng Pan and Jerry Hobbs have developed an “entry” sub-ontology of time, expressed in OWL, that is much simpler than the full ontology and provides all of what most users 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.

Additional DAML-Time documents:

Old versions:

Still to come:

Practical Temporal Ontology and Markup Language

This project, by George Ferguson and James Allen, is focused on the development of concepts and tools for representing temporal information. Temporal information is ubiquitous in real world situations. It includes dates of events (January 3, 2002, next Wednesday), durations of activities (drive for twenty minutes, wait about an hour), ordering between events (wait for Fred then drive to Rochester), and constraints between events (don't touch the button while the switch is on, only one flight can use the runway at a time), among other things.

Our objectives in this project are (1) the development of a practical ontology and markup language suitable for representing temporal information in realistic situations and (2) the development of tools and algorithms to assist in the coding and use of temporal information.

Our approach is to build on formally well-defined and extensively-studied model of temporal representation, Interval Temporal Logic (the so-called Allen algebra of time). This and other work on formal temporal ontologies provides the foundation for development of the more practical ontology. This will be specifically designed to support the representation of certain types of temporal information that occur regularly and are of value to end users. The goal is a markup language that allows users to naturally indicate temporal information without being ontology or temporal reasoning experts.

Under construction...

Last change: 28 Jul 2003 by ferguson