Towards Physarum Binary Adders

TL;DR

This paper demonstrates through computer simulations that the foraging behavior of Physarum polycephalum can be used to implement basic logical gates and a binary one-bit adder, simplifying previous designs.

Contribution

It introduces simplified models of Physarum-based logic gates and constructs a binary adder, advancing unconventional computing with biological substrates.

Findings

Physarum can implement two-input and three-input logic gates in simulations.

A binary one-bit adder can be assembled from these gates in the model.

The design's validity is confirmed through computer simulation.

Abstract

Plasmodium of \emph{Physarum polycephalum} is a single cell visible by unaided eye. The plasmodium's foraging behaviour is interpreted in terms of computation. Input data is a configuration of nutrients, result of computation is a network of plasmodium's cytoplasmic tubes spanning sources of nutrients. Tsuda et al (2004) experimentally demonstrated that basic logical gates can be implemented in foraging behaviour of the plasmodium. We simplify the original designs of the gates and show --- in computer models --- that the plasmodium is capable for computation of two-input two-output gate $<x, y> \to <xy, x+y>$ and three-input two-output $<x, y, z> \to < \bar{x}yz, x+y+z>$. We assemble the gates in a binary one-bit adder and demonstrate validity of the design using computer simulation.