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Full Title

Knowing When to Act


logic, knowledge, time, viewpoints


The IT support for large-scale organisations is often a complex, distributed, system. The characteristics of such systems mean that what users can, in principle, know about the system varies according to the users location and varies with time. For example, often it pays to wait until updates have propagated through the system before attempting to use updated information. The completion of this kind of process is often uncertain, time-varying and may be marked by a number of cues from the system that are not usually part of the "design" process. These features of computer-based systems are often part of the folklore of the organisation and can be difficult to capture.  Part of the goal of the DIRC Timing Theme is to develop intellectual tools to capture such timing features.

In this work we attempt formally to capture these features by developing a logic that incorporates both time and knowledge and consider how to enrich Object Constraint Logic to take account of these features. In the papers we apply these ideas to some simple examples and consider the extent to which we can capture notions of temporal validity in real-time data distribution systems. By subtle changes in design one can ensure that users can acquire the knowledge they need and thereby avoid some circumstances where users can never have the knowledge they need to act effectively.

In carrying out this work it has become evident that knowledge is linked to the capability to observe events and that this capactity is closely linked to the timeband the observation occupies.  Related work in the timing theme includes work on formal modelling of timing and microworld simulation studies.


The timing theme

Time bands

When to act

Time and context modelling


J. Kuester-Filipe and S. Anderson. On a time enriched OCL liveness template. International Journal on Software Tools for Technology Transfer (STTT), Springer, 2005.

J. Kuester-Filipe and S. Anderson: On a time enriched OCL liveness template. In Proceedings of the International Workshop on Specification and Validation of UML models for Real Time and Embedded Systems (SVERTS 2003), held in conjunction with the Sixth International Conference on the Unified Modeling Language, UML 2003, October 20 - 24, 2003, San Francisco, California, USA.

J. Kuester-Filipe, M.Felici and S. Anderson: Timed Knowledge-based Modelling and Analysis: On the Dependability of Socio-technical Systems. In Bagnara, S., Rizzo, A., Pozzi, S., Rizzo, F. and Save, L., editors, Proceedings of the 8th International Conference on Human Aspects of Advanced Manufactoring: Agility and Hybrid Automation, 27-30 May 2003, Rome, Italy, pages 321-328.

S. Anderson and J. Kuester Filipe: Guaranteeing temporal validity with a real-time logic of knowledge. In Proceedings of the 23rd IEEE International Conference on Distributed Computing Systems Workshops - First International Workshop on Data Distribution for Real-Time Systems (DDRTS 2003). Providence, Rhode Island, USA, 19-22 May 2003, pages 178-183, IEEE Computer Society Press.

M. Felici and J. Kuester Filipe: Limits in Modelling Evolving Computer-based Systems. Proceedings of the ACM Symposium on Applied Computing, SAC 2002, March 10-14 2002, Madrid, Spain. pages 706-710.


Stuart Anderson (Edinburgh)


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