
Winter 0.9.5 by Winter by Jonathan Rosenthal (Switzerland)
https://github.com/rosenthj/Winter
It is the top rated chess engine from Switzerland and has competed at top invite only computer chess events such as the Top Chess Engine Competition and the Chess.com Computer Championships. Its level of play is super human, but below the state of the art reached by the large, distributed and resource intensive open source projects Stockfish and Leela Chess Zero.
Winter has relied on many machine learning algorithms and techniques over the course of its development. This includes certain clustering methods not used in any other chess programs, such as Gaussian Mixture Models and Soft K-Means.
As of Winter 0.6.2, the evaluation function relies on a small neural network for more precise evaluations.