Let's Talk about Time
Dr Jixin Ma
University of Greenwich
15 May 2013, Watts 504 @ 1pm
We understand, when we speak of time; we understand also, when we hear it spoken of by another. However, what, then is time? If no one asks me, I know; but if I want to explain it to a questioner, I don't know. Generally speaking, time plays a fundamental and important role in modelling natural phenomena and human activities concerning the dynamic aspects of the world under consideration. However, complete and absolute temporal knowledge is usually not always available for many knowledge based systems, notably in the domain of Artificial Intelligence. Two folds of the problem of representing and reasoning with uncertain and incomplete temporal information are:
- How to represent various kinds of uncertain and incomplete temporal knowledge?
- How to construct a reliable method of inference, based on the representation?
Based on a time theory that takes both points and intervals as primitive, this talk presents a graphical representation for uncertain and incomplete temporal knowledge, which allows logical expressions of both absolute and relative temporal relations, supporting both logical conjunctions and disjunctions. In terms of a visualized framework, a computer aided case tool, called Visual Time, is demonstrated. Visual Time provides a user-friendly environment for describing scenarios with rich temporal structure in natural language, which can modeled in terms of Temporal Relationship Diagrams (TRD). A TRD can be automatically and visually expressed as a Time Graph, supported by an automatic consistency checker, which can derive a verdict that confirms if a given scenario is temporally consistent or inconsistent.