Here is an interesting paper, Probabilistic Complex Event Triggering, Daisy Zhe Wang, Eirinaios Michelakis, and Liviu Tancau, Computer Science Division, University of California at Berkeley, circa 2005.
One of the first things I noticed about the paper was the discussion of probability in the content of complex event processing, including Hidden Markov processes, Bayesian Belief Networks, and inference models.
The second thing I noticed was that David Luckham’s work on CEP at Stanford was not referenced anywhere in the Berkeley paper.
Posted by Tim Bass 
The Complex Event Processing Blog 