  We study Colored Workflow nets, a model based on Workflow nets enriched with
data. Based on earlier work by Esparza and
Desel[arXiv:1307.2145,arXiv:1403.4958] on the negotiation model of concurrency,
we present reduction rules for our model. Contrary to previous work, our rules
preserve not only soundness, but also the data flow semantics. For free choice
nets, the rules reduce all sound nets (and only them) to a net with one single
transition and the same data flow semantics. We give an explicit algorithm that
requires only a polynomial number of rule applications.
