Puzzle https://lichess.org/training/cn0Nw

I wonder if this puzzle https://lichess.org/training/cn0Nw meets the Lichess puzzle critera.
The move itself RxN is not hard to find. Many players would find it even in blitz. It gives black two pieces for his rook. And the initiative. Then it takes black an other 8 [computer] moves to win an other pawn and thus get a 2.0 material count advantage.

In most lichess puzzles, 2.0 seems insufficient, e.g. an exchange. What I thought was needed was:

Mate
Material advantage of >=3.0 on the board, or trivially [unstoppable passer]

Of course I see the comp eval in this case (-4.2) But I find this eval rather non-trivial. Have I misunderstood the criteria?

And many thanks to the Lichess team for all the magnificent work : )

I wonder if this puzzle https://lichess.org/training/cn0Nw meets the Lichess puzzle critera. The move itself RxN is not hard to find. Many players would find it even in blitz. It gives black two pieces for his rook. And the initiative. Then it takes black an other 8 [computer] moves to win an other pawn and thus get a 2.0 material count advantage. In most lichess puzzles, 2.0 seems insufficient, e.g. an exchange. What I thought was needed was: 1. Mate 2. Material advantage of >=3.0 on the board, or trivially [unstoppable passer] Of course I see the comp eval in this case (-4.2) But I find this eval rather non-trivial. Have I misunderstood the criteria? And many thanks to the Lichess team for all the magnificent work : )

IM zwenna

Counting the material at the end of the forced line is insufficient, this is not how Lichess puzzles work. The Stockfish evaluation of the final position is around -3.5, so Stockfish is rather sure it can win this position against an equally strong opponent.

In many high rated puzzles the evaluation is actually more difficult than the calculation, but there seem to be some rules of thumb which material imbalances in middlegame positions are usually good enough.

Two minor pieces vs rook
Two bishops vs rook and pawn
Minor piece vs three pawns (Ben Finegold: "A piece is worth nine pawns.")

Counting the material at the end of the forced line is insufficient, this is not how Lichess puzzles work. The Stockfish evaluation of the final position is around -3.5, so Stockfish is rather sure it can win this position against an equally strong opponent. In many high rated puzzles the evaluation is actually more difficult than the calculation, but there seem to be some rules of thumb which material imbalances in middlegame positions are usually good enough. - Two minor pieces vs rook - Two bishops vs rook and pawn - Minor piece vs three pawns (Ben Finegold: "A piece is worth nine pawns.")

MillenniumBug

Of course Stockfish wins this. I implied that strongly in my post.

And, Of course two pieces vs rook is a great advantage. But in Lichess puzzles I dont think I ever saw the solution to be Two minor vs rook...

Of course Stockfish wins this. I implied that strongly in my post. And, Of course two pieces vs rook is a great advantage. But in Lichess puzzles I dont think I ever saw the solution to be Two minor vs rook...

IM zwenna

@MillenniumBug said in #3:

And, Of course two pieces vs rook is a great advantage. But in Lichess puzzles I dont think I ever saw the solution to be Two minor vs rook...

I saw it quite often, along with the other material differences mentioned above. The rules of thumb I gave are solely based on my own experience after solving thousands of Lichess puzzles.

@MillenniumBug said in #3: > And, Of course two pieces vs rook is a great advantage. But in Lichess puzzles I dont think I ever saw the solution to be Two minor vs rook... I saw it quite often, along with the other material differences mentioned above. The rules of thumb I gave are solely based on my own experience after solving thousands of Lichess puzzles.

nadjarostowa

The criteria is: Black is much better at the end (as you say, around -4), whereas other moves only leave an equal position.

Evaluation the position as -4 is indeed the tricky part - and the stronger engines get, the crazier the evaluation tend to be. Nowadays, you might get a position with equal material, and the engine says +3. And you have hardly any idea why it is that high... this was unthinkable a couple of years ago, when the engines were much weaker, but also much easier to understand.

Fortunately, it is not necessary to understand the evaluation (which for a perfect engine would just be a mate score or draw), but rather to see that the solution is the best move. In this concrete position, you win some material, keep active pieces, and release some pressure on your d5 pawn.

The criteria is: Black is much better at the end (as you say, around -4), whereas other moves only leave an equal position. Evaluation the position as -4 is indeed the tricky part - and the stronger engines get, the crazier the evaluation tend to be. Nowadays, you might get a position with equal material, and the engine says +3. And you have hardly any idea why it is that high... this was unthinkable a couple of years ago, when the engines were much weaker, but also much easier to understand. Fortunately, it is not necessary to understand the evaluation (which for a perfect engine would just be a mate score or draw), but rather to see that the solution is the best move. In this concrete position, you win some material, keep active pieces, and release some pressure on your d5 pawn.

PurpleInferno edited

It's a 2-pawn material advantage at the end of the puzzle: 1.5 for two pieces vs rook, 0.5 for the bishop pair. It's a little on the low end for a puzzle solution, but not by so much that I'd suspect it's not enough to qualify as a solution. It's not like white has any compensation.

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