Mastermind GM Larry Kaufman introduces Dragon 2 by Komodo Chess

December 20, 2021

[December 20, 2021]  We have released Dragon 2 at komodochess.com. Dragon uses NNUE (Neural Network Updated Efficiently) technology, originally developed for the game of shogi. Komodo has a great deal of chess knowledge in its evaluation. Training an NNUE network based on this evaluation was both an advantage and a challenge, requiring experimentation with architectures and data generation of billions of positions. The reinforcement learning phase for Dragon is in its infancy, but is already showing great promise.

Dragon 2 is a huge strength improvement over Komodo 14.1, the last pre-dragon release, about 210 elo in standard mode, at CCRL blitz time control on one thread based on 10,000 game direct matches. With four threads, the gains were 198 elo in MCTS and 184 elo in standard mode. The improvement is due to the embedded neural network providing much more accurate evaluation and also in some sense gaining an extra ply or so of search by “seeing” some tactics that a normal eval won’t spot. Our testing also shows that Dragon is especially strong in Fischerandom (960) chess, which was confirmed when Dragon won the TCEC FRC 2021 championship. Dragon also won the 2021 TCEC Swiss championship (normal chess). We believe that Dragon will play in a more human-like style than standard Komodo since it relies on learning what actually works in games rather than just on pre-assigned values for eval terms.

Although Dragon 2 is only slightly stronger than the initial dragon version in standard mode, the MCTS mode when running under Windows is dramatically improved, about a hundred elo. Also the MultiPV play of standard mode is dramatically improved from the initial dragon release, again by about a hundred elo! Based on our testing, we now believe that Dragon 2 in standard mode is the strongest engine for analysis on most computers when displaying more than four lines of play at once. A new feature with Dragon 2 is “MCTS Optimism”, which allows the user to make Dragon “trust” its own judgments more while being less confident in predicting the opponent’s moves. Other features added since Komodo 13 include Armageddon mode, more levels, Personalities, and Auto-Skill. Standard mode is usually the stronger mode objectively, while MCTS mode is usually better at setting problems for human opponents as it does not assume perfect defense. Skill levels have been adjusted to use the Dragon NNUE without much change in the strength of a given skill level; we think this makes the skill levels more "human-like".