# Digital System Reconstruction by Pairwise Transfer Entropy

## TL;DR

This paper proposes a low-order, pairwise transfer entropy method for reconstructing digital system structures from binary data, effectively distinguishing causal links and quantifying coupling strength.

## Contribution

It introduces a practical, low-dimensional pairwise TE framework that reliably detects causality and infers structural connectivity in digital systems.

## Key findings

- TE values differ significantly between connected and unconnected pairs
- TE value correlates quadratically with coupling strength
- Method is robust across various systems and regimes

## Abstract

Transfer entropy (TE) is an attractive model-free method to detect causality and infer structural connectivity of general digital systems. However it relies on high dimensions used in its definition to clearly remove the memory effect and distinguish the direct causality from the indirect ones which makes it almost inoperable in practice. In this work, we try to use a low order and pairwise TE framework with binary data suitably filtered from the recorded signals to avoid the high dimensional problem. Under this setting, we find and explain that the TE values from the connected and unconnected pairs have a significant difference of magnitude, which can be easily classified by cluster methods. This phenomenon widely and robustly holds over a wide range of systems and dynamical regimes. In addition, we find the TE value is quadratically related to the coupling strength and thus we can establish a quantitative mapping between the causal and structural connectivity.