Time to get a piece of the modeling pi

But there is another pi that some may be less aware of – the theoretical formalism of pi calculus in process algebra. Thank Robin Milner, the brain behind the theory of pi calculus, that approaches systems as fundamentally able to reorganize themselves through interaction (see Milner, 1999). Jeannette Wing (2002) explained the utility of pi calculus in a way that I found highly approachable (or as cuddly that process calculus can be). The process is that mysterious force based on inputs that control a system (see Wing, 2002). The channels tie together through some mode of communication (or relationship) (see Wing, 2002).

 Systems are made of components that are interdependent. Also the process can involve any number of balancing and reinforcing factors that loop together. Displaying a recognized connection to another agent is, at its center, systemic. For example, when using pi calculus theory within computer code modeling, what is of interest is the process calculus of the messaging (connections) that may be measured asynchronously (with a time delay) or synchronously (at the same time). The computer code using pi calculus is an approximation, replicating the nature of the concurrent inputs/outputs into the system. Students in software engineering class accept, perhaps with unabashed relief, that approximation of “truth” of such calculus and move on to get their modeling done. Maybe policy needs another definition of truth.

What can policy learn from this theory of pi?


1.      There should be an accounting of the systemic process underlying the policy. This may include looking at the interdependence and feedbacks among elements of the system, ongoing assessments of the past policy successes and failures, as well as changing landscape of epidemiological evidence.

2.      Dynamic changes in inputs/outcomes are debated beyond the mental models offered around the table (e.g. use of formal modeling).

3.      Overlap (concurrence) of different systems at play in the policy should be explored.



Milner, R. (1999). Communication and Mobile Systems: The Pi Calculus. Cambridge: Cambridge University Press.

Wing, J. (2002). FAQ on pi-calculus. Retrieved on February 18, 2014 from http://www.cs.cmu.edu/~wing/publications/Wing02a.pdf.



About Michele Battle-Fisher

This is an archive of the Orgcomplexity Blog. Please follow me at the following sites: mbattlefisher.wix.com/orgcomplexity Michele Battle-Fisher (Facebook author page) www.linkedin.com/in/mbattlefisher mbattlefisher (Twitter) michele.battle.fisher (Skype) Author Website http://amazon.com/author/michelebattlefisher

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