"Microsoft officially opened the artificial intelligence toolkit CNTK (Computational Network Toolkit) in the previous stage. Chinese has artificial intelligence, but the actual English word translation is actually a computing network toolbox. From another angle, it can be understood as a A way to implement artificial intelligence through calculations. The seemingly professional name must have a certain mathematical foundation behind it. In this series of articles, we should try to explain these mathematical principles in plain language. If necessary, we will give relevant links (it may also be that we will write articles separately).