Koivisto
Koivisto,
an UCI compliant open source chess engine by Kim Kåhre and Finn Eggers, at times supported by Eugenio Bruno, written in C++,
and first released on GitHub in September 2020 under the GPL v3.0.
The bitboard engine provides automated evaluation tuning by logistic regression,
either using stochastic gradient descent or AdaGrad.
Koivisto 5.0 in July 2021 replaced the perceptron approach of a real-men-evaluation (RME) by an own NNUE, as of Koivisto 5.9, with two layers [2].