It started with the tactical puzzles. They're derived algorithmically (using Stockfish analysis) from games actually played on the website. This alone is fascinating:
My favorite thing about the puzzles though is that I can easily explore suboptimal solutions using lichess's analysis tools. If I ever got a puzzle wrong, my first question wouldn't be what the right move was, but rather why my move was bad. This is trivial to answer with the analysis tools. You can even see the game that the puzzle was derived from and see what moves the players actually made.
The site is just a goldmine.
Did stumble upon a bug though. I had three puzzles which I thought were buggy. I forgot the URL and details on the first one (so it may or may not been buggy), and I was flat out wrong about the second one (a bishop was making sure a horse couldn't move which I thought could be used to take the piece supposedly causing checkmate).
My third one though is clearly buggy: https://en.lichess.org/training/61461
Its not over when the game says victory. Black has 4 (! EDIT: 3, but still) ways to avoid the checkmate, and Stockfish also suggests these moves.
Nevertheless a very nice project, including Stockfish integration. I can't repeat that enough! App of the year for me.
The goal is just to find the most optimal move given the board configuration. In that particular position, white can use its knight to simultaneously attack the black king and queen. Since the king is more important, it must be moved, effectively forcing black to sacrifice their queen. So the goal of that puzzle isn't to checkmate black, but to use a temporary check against black to capture the black queen (at the cost of a white knight -- still a worthwhile exchange, since the queen is much more powerful than a knight).
FWIW, I do not agree is (always) more powerful than a knight, but generally they are (while a queen is more powerful than a rook or bishop which is almost always better, a knight has a unique utility).
Furthermore they sympathetically state:
"Lichess mobile is developed and translated to 80 languages by volunteers. Just like the website, it's 100% free forever, and there will never be advertisements. This is humanist software, made open source for the love of chess and user freedom."
But there are two things on my wishlist 1) make the website work off-line 2) new variant to change the chess rules to accommodate a smaller board 5x6, 4x5 or 6x6 for even shorter games.
That makes no sense. You can have games as short as you want. Just play using a different time control. I play 1+2 (minute plus seconds) and those games last 2 to 3 minutes at most.
BTW with variants, you're not really playing chess anymore. You're playing a different game with chess pieces. Not all the strategy and tactics transfer well if at all.
Since security is fundamentally increasing costs enough to outweigh the prize, I feel like this makes it.
It's purely donation driven and he pulls a small salary from whatever's leftover after buying enough servers to keep the site up.
( link came from here https://en.lichess.org/patron )
Its source code is also really interesting, it makes me want to learn Scala.
It's been around at least as far back as 2010. Here is a 6 year old HN submission about it: https://news.ycombinator.com/item?id=1927188
It can be rather addicting, also. On more than one occasion, my wife has gotten annoyed with me just sitting on the couch for hours trying to solve the puzzles :P
Many players enjoy using the opening simply because it leads to dangerous and exciting games, so it makes sense that Stockfish and other engines would prefer conservative opening lines.
>>> best chess engines are still worse at analyzing openings than humans.
>> Is that actually the case, or perhaps humans try a lot of sub-optimal opening lines?
> Sub optimal from the perspective of the AI
There's no perspective involved: optimal play is perfect play, assuming the opponent also plays perfectly. If a move is sub-optimal for White that means White has a better move, no matter what the opponent plays.
Sure, in practice a non-perfect-player might do better playing a sub-optimal move A rather than a better move B, because they don't know how to continue after B or because their non-perfect opponent ends up replying even more sub-optimally to A.
But just because I can manage to pull a fool's mate on someone that doesn't make it an optimal opening. One could say I might be "optimizing" for fun or for time, but if you redefine optimality arbitrarily then the original claim might as well be "chess engines are worse than humans at analyzing openings because they play better than humans".
PS: I'm not claiming that chess engines are better or worse than humans.
And, incidentally, playing an inferior move while hoping the opponent makes a mistake is bad even if it works, as it really hinders your progress.
Restricting yourself to perfect opponents is very silly firstly, because there are no perfect opponents because chess is unsolved. So right out of the gate our definition assumes the counterfactual for all chess games every played and is both inaccurate (does not describe actual chess) and impractical (cannot be implemented)
Secondly, if there were such an opponent (which is not at all clear there ever will be), there is no way within the rules of chess to detect whether or not we face it in a given game. Imperfect opponents are allowed to play chess, and assuming they are all perfect while a defensible strategy is merely one of several.
Thirdly, it leads to very counterintuitive results. Consider the case in which chess is solved and well-balanced (e.g. a perfect opponent P can force a draw). We modify P to create opponent NP. NP behaves as follows: if NP's opponent is consistent with P, NP will implement P (e.g. force a draw), if NP's opponent deviates from P, NP will lose (forefeit or make bad moves). Therefore everyone can beat NP except "optimal" algorithm P, which can only force a draw. So now we have an "optimal" algorithm with a 0 tournament rating.
In reality the whole "perfect opponent" thing is mostly a notational convenience for Zermelo's Theorem. Which is very interesting and useful if you are writing a proof, less interesting if you are trying to win a chess tournament. A more practical definition of "optimal" is something like "wins a lot of games".
And given that you want to become a better chess player, isn't it better to start learning the best lines from the start?
For example, if chess is a win for white, you play black, and you have a halfway decent opponent, he will know what black's best defense looks like (that is: the one that takes him the most moves to win). Replaying that gives you zero chance of winning or drawing. Deviating from the beaten path cannot decrease that chance, and may increase it.
It is similar when chess, played optimally by both players, turns out to be a draw, and you want to win, but in that case, you may not want to give up your assurance of a draw, so you may play less weird moves. You still will want to play moves that lead to plays your opponent is weak at, though.
Sure, but the King's Gambit is just an opening, and you'd have to rely on lazy mistakes to guarantee a win 10 moves ahead that early in the game.
To the extent that an AI approaches perfect play more closely than a novice or masters from the 19th century, shouldn't we go learn from the AI?
One interpretation of Stockfish here is 'I don't think this is a very strong opening'. To the extent that it's correct, stronger players will not play that opening very much, so spending time to learn it seems potentially wasteful.
For perspective, Bobby Fischer created a version of chess which randomized the game because even in his day, he was annoyed that some players that he felt were far inferior at playing chess, could actually better memorize opening lines and enter the mid game with an advantage.
So the answer is that players very well have been learning from AI.
>To the extent that an AI approaches perfect play more closely than a novice or masters from the 19th century
AI has become better than even the top chess players of today.
the game engine is strong, 5d running local on my phone, no server!
here for android: https://play.google.com/store/apps/details?id=jp.co.unbalanc...
i hear it exists for iOS too
I found it worth the price. And the lower kyu AI was actually fun to play.
 - https://en.lichess.org/stat/rating/distribution/blitz
It appears this is not the case, anymore. I logged in to both servers this afternoon, and counted the number of players rated over 2350. Lichess had 50, ICC had 6. I logged in again tonight and saw roughly the same ratio.
I never used chess.com, so I cannot really compare. I'm an avid user of the linked site, and use it play both with friends and users around the world. So far it's been a great experience, and I still have lots to discover : chess studies, tournaments and alternate game modes.
Your connection is not private
Attackers might be trying to steal your information from en.lichess.org (for example, passwords, messages or credit cards). NET::ERR_CERT_AUTHORITY_INVALID
This resolves after 2-3 days and then within a week it again reappears.
Now with that said, this looks quite good and really broaches chess in a modern way in terms of learning. I sure have stacks of books that I wish were just software, mostly on studying chess tactics
Not acceptable, Mr Stockfish!
Actually, the King's Gambit has been (essentially) solved: https://en.chessbase.com/post/rajlich-busting-the-king-s-gam...
There is only one move that doesn't lose by force after 2. ... exf4, and that is the strange-looking 3. Be2. Does that mean this opening is a "mistake"? Well, maybe not, obviously a human wouldn't know the perfect lines, but personally I wouldn't play it :)
Either way, I'll certainly be using this feature a lot. Kudos to the folks at Lichess.
> There is only one move that doesn't lose by force after 2. ... exf4, and that is the strange-looking 3. Be2. Does that mean this opening is a "mistake"? Well, maybe not, obviously a human wouldn't know the perfect lines, but personally I wouldn't play it :)
It was an April Fools Prank. Apparently a good one.
Considering how much Stockfish is stronger than those masters, those moves could be really wrong despite being playable in human vs human games.
Hoowever we don't know the estimated ELO of Stockfish as used by Lichess.
For books, Beginners Mind by Jeremy Silman is pretty good, as is his endgame book. Logical Chess by Cherenev is also a great introduction to how skilled people think about games but takes a different approach than Silman.
 - http://chesstempo.com/
Or can I upload a PGN from, for example @fbchess?