Avoiding unstructured workflows in prerequisites modeling

Integrating prerequisite relationships, partially defined as graph components, produces a directed graph that corresponds to a well-defined and well-behaved workflow consisting only of and-splits and and-joins. Such a workflow often cannot be transformed to a structured workflow. This paper presents an approach to producing a corresponding structured workflow that will, with some adjustments in the runtime, correspond to the original unstructured workflow. The workaround is based on element cloning and on a workflow wrapper handling clones in order to avoid multiple element instances. An algorithm for finding clones and an algorithm for reducing the number of clones are proposed. Correctness of the algorithms is analyzed and some drawbacks and possible improvements are examined.