I don’t know whether you said that a CEP application must necessarily have a model. It may have, or it may not. A rule-based approach (in its general acceptation) is not considered as a model. In the AI terminology, rules are considered as “shallow knowledge”, while models are considered as “deep knowledge”. Shallow knowledge expresses the people’s experience, links symptoms to causes directly, while deep knowledge establishes the links using a model, and the model can be interpreted. Shallow knowledge is very helpful in many cases, and as deep knowledge it also allows detecting situations. Of course, the cooperation of both is desirable to build more powerful systems. I did a rapid search, and below are 3 entries for reference:
T. Weise, M. Zapf, and K. Geihs. Proceedings of BIONETICS 2007, 2nd International
Conference on Bio-Inspired Models of Network,
Information, and Computing Systems, Radisson SAS Beke Hotel, 43. Terez krt., Budapest
H-1067, Hungary, Institute for Computer Sciences, Social-Informatics
and Telecommunications Engineering (ICST), IEEE, ACM, (December 2007)
D. Kim, H. Cao, K. Jeong, F. Recknagel, and G. Joo. Ecological Modelling, 203 (1-2):
147--156(24 April 2007)Special Issue on Ecological Informatics:
Biologically-Inspired Machine Learning, 4th Conference
of the International Society for Ecological
Informatics.
J. Davidson, D. Savic, and G. Walters. Developments in Soft Computing, page 175--182. De Montfort University, Leicester, UK, Physica Verlag, (29-30 June 2000. 2001)
M. Hearst. Proceedings of the 14th conference on Computational linguistics-Volume 2, page 539--545. Association for Computational Linguistics Morristown, NJ, USA, (1992)