lkaufman wrote: ↑Tue May 04, 2021 5:53 pm
Komodo Dragon 2 is released today at komodochess.com. As usual, it is free for subscribers, priced the same as Dragon (1), which itself will be marked down 20% as will Komoro 14.1 shortly. Anyone who bought Komodo 14 or later version gets 20% discount from these prices.
The improvements over Dragon 1 are primarily in two areas. MultiPV search (in standard mode) has been completely rewritten, and now is
about a hundred elo stronger than in Dragon 1 (or older Komodo versions). It is sufficiently improved that we no longer advocate using MCTS mode
just for the MultiPV benefits it provides. The MCTS mode is also improved in Dragon 2, dramatically so when using Windows, where the elo gain
over the original Dragon is also about a hundred elo. There is a new UCI option called MCTS Optimism, which when set to a positive number
(default is +10) makes Dragon "trust" its own internal move preferences more while exploring the opponent's choices more; a higher setting
might be appropriate for a human opponent. MCTS mode remains the best option for super-strong but human-like play and for preparing openings for
human opponents who will not have access to engines while playing. The standard mode when not using MultiPV has also been improved, but only by
an estimated ten elo. It is nearly the same as the version that won the recent TCEC Swiss, and is a slight upgrade from the version that beat
Stockfish in the fifty game final match of the TCEC chess960 (FRC) championship.
We believe that the MultiPV search is now more effective than the Stockfish MultiPV search, and that if MultiPV is set to more than 4
Dragon 2 is now the favorite against Stockfish 13 on typical modern hardware.
Dragon 2 comes with an AVX2 version (suitable for most PCs since 2013) and a standard one. The AVX2 version is quite a bit faster and
stronger, and we hope that the testing groups will limit testing to AVX2 machines if at all possible. It probably doesn't matter when running
against Stockfish 12 or later, which also gets a lot out of AVX2, but it makes a big difference against programs not using NNUE. There is no
BMI2 version for Dragon 2 as we have not found any meaningful benefit to BMI2 beyond the benefit of AVX2.
Finally, for those who bought Komodo 14 or 14.1 but not Dragon, the strength gains from Komodo 14 in either MCTS or standard mode are nearly
200 elo, only slightly less from Komodo 14.1. All estimated elo gains are at the CCRL blitz time control of 2' + 1" increment, and use Ordo rather
than BayesElo.