The process of training an artificial neural network involves iteratively adapting its parameters so as to minimize the error of the network's prediction, when confronted with a learning task. This iterative change can be naturally interpreted as a trajectory in network space -- a time series of networks -- and thus the training algorithm (e.g. gradient descent optimization of a suitable loss function) can be interpreted as a dynamical system in graph space. In order to illustrate this interpretation, here we study the dynamical properties of this process by analyzing through this lens the network trajectories of a shallow neural network, and its evolution through learning a simple classification task. We systematically consider different ranges of the learning rate and explore both the dynamical and orbital stability of the resulting network trajectories, finding hints of regular and chaotic behavior depending on the learning rate regime. Our findings are put in contrast to common wisdom on convergence properties of neural networks and dynamical systems theory. This work also contributes to the cross-fertilization of ideas between dynamical systems theory, network theory and machine learning

通过分析网络轨迹和学习过程中的动力学特性，研究了浅层神经网络在简单分类任务中的演化过程，发现不同学习速率下的动力学和轨道稳定性，这一发现与神经网络和动力学系统理论的常见智慧相对照，为动力系统理论、网络理论和机器学习之间的相互交流提供了贡献。

人工神经网络轨迹的动力稳定性与混沌