Date Added: Mar 2011
The authors address the problem of comparing the expressiveness of work-flow specification formalisms using a notion of view of a work-flow. Views allow to compare widely different work-flow systems by mapping them to a common representation capturing the observables relevant to the comparison. Using this framework, they compare the expressiveness of several workflow specification mechanisms, including automata, temporal constraints, and pre-and-post conditions, with XML and relational databases as underlying data models. One surprising result shows the considerable power of static constraints to simulate apparently much richer work-flow control mechanisms.