说明：  深度学习（Deep Learning, DL）或阶层学习（hierarchical learning）是机器学习的技术和研究领域之一，通过建立具有阶层结构的人工神经网络（Artifitial Neural Networks, ANNs），在计算系统中实现人工智能
(learning (also known as deep structured learning or hierarchical learning) is part of a broader family of machine learning methods based on artificial neural networks.this is a simple note for DL.)