How does Lichess go about collecting puzzles from player games? Do players submit their game situation to Lichess for consideration as a puzzle? Or does Lichess automatically select positions from player games where tactics are available?
I have some good puzzles from my games and I would like to send them to moderators for consideration. How should I go about it?
It doesn't work like that. The puzzles are automatically generated, I mean, an engine pick them up from real games.
What Giri said, the puzzles are taken from real Lichess games. I assume they have to be analysed. When a game has a forced continuation that wins material or delivers checkmate it may be added to the training section.
I have solved around 10,000 puzzles and I feel safe to claim that most of them don't have a forced continuation.
Say you play the first best move, then the computer has the option to play either one of many moves which have almost an equal disadvantage. So you select the second best move. And then again the computer has some non-forced moves to choose from.
NOTE that there is only one best move each time, but still different lines of play.
So in essence, most of the time, it's not a forced sequence.
Moreover, consider a situation where black plays a move, say Nd4. Now this Nd4 may give white a sudden advantage of +2. But how does the computer determine whether it's a puzzle or just a positional advantage?
Think about it.
Now you may say that if White has a sudden advantage AND the possibility to gain material immediately, it's a puzzle. Otherwise it's not.
There's a refutation for this too.
I've seen puzzles which do not lead to material advantage or mate. Like an exchange of a rook and pawn for knight and bishop(I got this puzzle recently).
A position can only qualify for a puzzle if there is one clearly best move in the initial position and one clearly best move after the first best move from both sides. The solution can continue for more than two moves, but is always at least two moves long.
There is a whole article made by the developers and well writtten that answer to your question
@Aza94 :
lichess.org/blog/U4sjakQAAEAAhH9d/how-training-puzzles-are-generated I think you will find everything you want.
PS: Additionnal infos here
fr.lichess.org/blog/WDY6cCEAALYi5Xg2/puzzles-update