Representation of Shape Mediated by Environmental Stimuli in Physarum polycephalum and a Multi-agent Model

TL;DR

This paper explores how Physarum polycephalum and a multi-agent model can represent the shape of point datasets, demonstrating shape approximation and morphological computation through environmental stimuli and growth parameters.

Contribution

It introduces methods for shape representation using Physarum and a multi-agent model, including approximations of convex and concave hulls based on environmental stimuli.

Findings

Physarum networks can approximate dataset shapes.

Growth parameters control convexity and concavity in shape modeling.

Environmental stimuli influence shape formation in the model.

Abstract

The slime mould Physarum polycephalum is known to construct proto- plasmic transport networks which approximate proximity graphs by forag- ing for nutrients during its plasmodial life cycle stage. In these networks, nodes are represented by nutrients and edges are represented by proto- plasmic tubes. These networks have been shown to be efficient in terms of length and resilience of the overall network to random damage. However relatively little research has been performed in the potential for Physarum transport networks to approximate the overall shape of a dataset. In this paper we distinguish between connectivity and shape of a planar point dataset and demonstrate, using scoping experiments with plasmodia of P. polycephalum and a multi-agent model of the organism, how we can gen- erate representations of the external and internal shapes of a set of points. As with proximity graphs formed by P. polycephalum, the behaviour of the plasmodium (real and model) is mediated by environmental stimuli. We further explore potential morphological computation approaches with the multi-agent model, presenting methods which approximate the Convex Hull and the Concave Hull. We demonstrate how a growth parameter in the model can be used to transition between Convex and Concave Hulls. These results suggest novel mechanisms of morphological computation mediated by environmental stimuli.