Multinomial Diffusion

Hi, Emiel Hoogeboom

I am reading your paper <Argmax Flows and Multinomial Diffusion: Learning Categorical Distributions>

I was confused in eq13:

<img width="1089" alt="image" src="https://user-images.githubusercontent.com/10150470/226642944-bf62614c-6fa0-4ca8-af94-f73ebe2ea310.png">

Can you giving me more details about it? it will be great help for us!

Thanks,

Weikun