Muon is an optimizer for the hidden layers in neural networks. It is used in the current training speed records for both NanoGPT and CIFAR-10 speedrunning. Many empirical results using Muon have already been posted, so this writeup will focus mainly on Muon’s design. First we will define Muon and provide an overview of the empirical results it has achieved so far. Then we will discuss its design in full detail, including connections to prior research and our best understanding of why it works.
