Scala Bigraph is a Scala implementation of Robin Milner's Bigraph model. A Bigraph is a data structure that entails two graphical structures: a forest and a hypergraph. The forest is used to model nested location of nodes while the hypergraph is used to model connectivity between nodes.
The library follows as faithfully as possible the syntax and semantics defined in [1] with some modifications to make the mathematical model easy to use as a scala library. We pinpoint these modifications in the Details section below.
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Place Graphs and Link Graphs independently in two different traits,
PlaceGraphandLinkGraph, and combined in a third trait calledBigraph. This gives the flexibility for a user to model only placing structures, linking structures, or both. -
The library currently supports concrete bigraphs, i.e., nodes and edges are named. In bigraphical terminology this is known as support. Node support is modelled generically, i.e.,
Bigraph[A]implements a bigraph with nodes of typeA. Edges do not currently have a generic type.
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More than a data structure, the bigraphical framework is a model of computation named Bigraph Reactive Systems (BRS). The dynamics is modelled using reaction rules that define how a given match in a bigraph can change. The next step for ScalaBigraph is to provide an implementation of BRS.
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Robin Milner provides in [1] a semantics for bigraphs without support, i.e., nodes and edges are not named. These are called Abstract Bigraphs. An implementation of Abstract Bigraphs is also an objective for ScalaBigraph.
This library is a personal project aimed primarily, but not exclusively, at the Bigraph community. This is still a work in progress and feedback is more than welcome!
[1] R. Milner, The Space and Motion of Communicating Agents. Cambridge University Press, 2009.
Developer: Eloi Pereira, eloi@berkeley.edu, http://eloipereira.com