[HN Gopher] How some common material imbalances affect your win-...
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How some common material imbalances affect your win-rate
Author : Luc
Score : 154 points
Date : 2023-06-12 21:20 UTC (1 days ago)
(HTM) web link (lichess.org)
(TXT) w3m dump (lichess.org)
| AdamH12113 wrote:
| Neat results! I am very much a rank amateur, but it looks like
| these results roughly align with the traditional 1-3-5-9 point
| values for the pieces, with a couple exceptions. Advantages of a
| single pawn, minor piece, or rook have proportionate values
| similar to what you'd expect. In particular, bishops and knights
| are very close with bishops being worth a tiny bit more. Winning
| the exchange is a sizeable advantage. Trading a rook for two
| minor pieces is an advantage except at the lowest skill levels.
|
| Two rooks turn out to be significantly worse than a queen instead
| of slightly better. But the most surprising thing to me is that
| having the two bishops seems to be worth almost nothing -- close
| to 50% odds across skill level. A single pawn advantage is more
| valuable! (The article says "4-5% more likely to win" at Elo
| 1200-1400, but that doesn't match the graph.) These surprising
| results were also more consistent across skill level, while the
| well-known advantages are worth significantly more to skilled
| players.
| rmetzler wrote:
| > In particular, bishops and knights are very close with
| bishops being worth a tiny bit more.
|
| I don't think so, and I would like to see the author look in
| the data for 2 knights vs 2 bishops. My gut feeling is that
| knights are hard to block and can attack every square, while
| bishops can only attack their color, so half the board. They
| can't protect each other and rely on pawns for this.
|
| I'm happy to trade my knights for the pawns, but I would like
| to see if I'm wrong.
| compiler-guy wrote:
| Bishops have a great deal more mobility than knights. A
| knight in the wrong corner takes several moves to catch up to
| a distant passed pawn. A bishop needs far fewer.
|
| Generally the trade off is a bishop pair, where you do have
| all the squares covered, vs the slower knights, who are also
| the only pieces that can threaten a piece without being
| threatened back.
|
| The advantages are highly position dependent, with closed
| games largely going to the knights and open games going to
| the bishops pair.
|
| But most games turn into open games at some point, so
| statistically the bishops end up better.
| lordnacho wrote:
| What does "clean" mean in this context? What makes you up a pawn
| "cleanly"?
| PeterisP wrote:
| Contrary to the definitions in the other answers, I'd assume
| that this refers to selecting positions from the database where
| that's the only difference in material - so "clean up a pawn"
| means that all the other figures are the same, that there isn't
| also a bishop vs knight difference, for example.
|
| I really doubt if there was any attempt to check if there's
| some "strategic compensation" - how would you do that at a
| large scale? I doubt that even running a solid chess engine
| evaluation on all these positions is feasible, you need
| something where you can simply/cheaply filter positions from
| the database and then just count the winrate.
| [deleted]
| beyondCritics wrote:
| I agree, this is the first annoying question to ask. As a
| seasoned club player, i believe to know that "clean Pawn up"
| means chess wise roughly what you think it means, namely: a)
| You are in a position, where it really does make sense to count
| pawns, a so called "quiet" position would be one of those. b)
| Your opponent has no pawn compensation of any kind, not even in
| the form of a nuisance. I personally learned this expression
| from GM Nakamura. Clean pawns were unknown before the "golden
| era of chess", you could utilize the idiom "ceteris paribus"
| instead, this was used by the old german vice WM Tarrasch.
|
| Hence it should be clear to anyone that without engine
| assistance it is totally impossible to determine for 10^6 games
| if a certain material difference was "clean" or not. Most
| likely he just checked for a stability over n consecutive
| moves, at least this is the usual way. Others have noted more
| problems, that might help put his highly deviating, washed out
| results in order.
| [deleted]
| iib wrote:
| I think it means that the opponent does not gain a strategic
| advantage from an exchange. You both have good enough positions
| and you are simply a pawn up.
| WJW wrote:
| From the other imbalances listed (like being up "the
| exchange"), I take it that they mean being up a pawn without
| having to give up anything in return. For pawns that is kinda
| obvious, but for more valuable pieces like a rook you can win
| it "cleanly" or maybe you take it with a pawn and then
| immediately lose the pawn.
|
| You can of course give up material for positional advantages as
| well, but from the article I don't think the author analyzed
| that. It would be difficult to accurately measure that anyway,
| some positions can be up +5 points according to the computer
| but only if you find 20 perfect moves in a row. Needless to
| say, most humans would not find those moves especially in the
| lower ELO brackets that the article analyzed.
| C-x_C-f wrote:
| Apart from what WJW said, it's not an objective criterion but
| it essentially means that you don't lose out in terms of
| initiative or position. A counterexample might be accepting the
| queen's gambit with black (i.e. 1. d4d5 2. c4cxd4), that way
| you win a pawn but you arguably give white an advantage in
| development (an in many cases white will be able to recapture
| the pawn as a result)
| mtlmtlmtlmtl wrote:
| "Cleanly" in chess parlance means you're up a pawn, and there
| is no "compensation" for the other player. I.e there are no
| other advantages in the opponents position that make up for the
| fact they're down a pawn(things like an attack on your king,
| piece activity, pawn structure).
|
| In simple mathematical terms a clean material advantage is:
|
| Overall eval >= material eval
|
| If overall eval < material eval, then compensation(other
| player) > 0 = "the opponent has some compensation for the pawn"
| EricMausler wrote:
| I agree with this question. How was clean determined in the
| dataset?
|
| Knowing how the word is used in chess is not enough to know
| where the line was drawn in the data here, which is the basis
| for the entire analysis shown.
| ifdefdebug wrote:
| I guess you put the game position right after the pawn
| capture into a good chess engine and check if you're one
| point up a a result.
| bitshiftfaced wrote:
| This would mean that, in the case of "up 2 rooks for a
| queen," the board would evaluate to a player's advantage
| even though that player would tend to lose at the highest
| level. I think something weird must be going on.
| nebulous1 wrote:
| Should have been defined (along with more information about the
| data set), but I assume it means that the opponent has no
| tactic that wins them material. For instance if I just take
| their protected bishop with my bishop then I'm briefly up a
| bishop. So it would not include that situation or where the
| trade is more complicated.
| janalsncm wrote:
| Would be interesting to see material imbalances as a function of
| plies into the game. As in, we know an extra pawn is more
| important in the endgame than in the opening, but how much more?
| KingOfCoders wrote:
| (Please Lichess, this is not ELO)
| nebulous1 wrote:
| Honestly "Elo" is commonly used to denote most Elo-like
| systems. I don't think it's confusing here.
|
| Also, it's "Elo" not "ELO".
| evandale wrote:
| One of my favourite things on the internet is when someone
| tries to make a pedantic correction and someone else comes
| along with something that's even more pedantic.
|
| Thanks for giving me a good start to the morning!
| smatija wrote:
| This is, if I see correctly, not official Lichess blog, but
| personal blog of marcusbuffett (hosted on lichess). Lichess
| offers personal blogs for some months now.
| shawabawa3 wrote:
| What does this mean?
| jackmott42 wrote:
| OP is making an unimportant pedantic point.
| [deleted]
| czx4f4bd wrote:
| Quoting Wikipedia because I'm lazy:
|
| > The Elo rating system is a method for calculating the
| relative skill levels of players in zero-sum games such as
| chess. It is named after its creator Arpad Elo, a Hungarian-
| American physics professor.
|
| https://en.m.wikipedia.org/wiki/Elo_rating_system
|
| There are other rating systems that are similar, but people
| commonly call any similar rating system "Elo". In this case,
| Lichess uses
| https://en.m.wikipedia.org/wiki/Glicko_rating_system, so the
| GP is arguing against calling it "Elo". I think it's kind of
| a pedantic point given that more people will understand "Elo"
| than "glicko-2", but I suppose "rating" would be clearer than
| either term.
|
| https://en.m.wikipedia.org/wiki/Chess_rating_system
| nebulous1 wrote:
| lichess uses glicko 2
| ladberg wrote:
| Am I misunderstanding something or is there a glaring statistical
| error here? I think this analysis works if the matches are all
| between two players of _truly_ identical skill that will roughly
| win 50% of the time against the other, but that 's not really the
| case here. They attempt to do that by controlling for Elo but I'm
| decently sure that you could pick any two players of the same Elo
| on lichess and one will win the majority of games.
|
| Now if we assume there is often a slightly better player in these
| games, the better player will more likely get into an
| advantageous position early in the game _and_ win more often, but
| not entirely because they got into the more advantageous
| position. What I 'm trying to say is that someone who is up a
| rook will win partially because they're up a rook and partially
| because they are likely a better player in the first place and
| will continue to play better than their opponent.
|
| I think to do this study correctly you'd need to place new
| players in a random position drawn from the dataset and actually
| evaluate the win rate without the confounding factor of having
| gotten into that position in the first place.
| spoonjim wrote:
| > I'm decently sure that you could pick any two players of the
| same Elo on lichess and one will win the majority of games.
|
| I think that's true at 2000+ but at my rating (500) it's just a
| comedy of blunders
| fairity wrote:
| > I'm decently sure that you could pick any two players of the
| same Elo on lichess and one will win the majority of games.
|
| Interesting hypothesis, but my intuition is that this effect is
| small. It should be easy to measure. Just take random matches,
| and study winrate when a player has beaten their opponent once
| before.
| yamazakiwi wrote:
| Players can also swap back and forth between winning a
| majority of games, so it depends on the amount of games we're
| talking about.
| queuebert wrote:
| That's exactly what Elo controls for: all things, being equal,
| what is the skill component. Now there could be a second-order
| effect in which a higher Elo player is _even better_ at winning
| from an advantageous position, but given large enough samples
| this should be in the mix.
| ladberg wrote:
| Yeah I guess my claim is that two people of the same Elo on
| lichess are likely to not be perfectly equal. If the average
| winrate of any random two players with the same Elo is
| something like 60/40 (random speculation) then you'd bias the
| results in the article enough to create the kind of graphs
| shown.
|
| The problem is that this doesn't really average out with more
| samples.
| BurningFrog wrote:
| I accept that players with the same ELO can have unequal
| strength.
|
| But I don't see how that wouldn't average out over lots of
| games?
| ladberg wrote:
| The probability of player A being up a rook over player B
| is higher when player A is better than player B, even if
| their Elo is the same. So the author has picked scenarios
| where player A is already more likely to be better than
| player B but assumed they were of equal skill, which will
| cause the results to be biased.
|
| If I have time later I'll try to whip up a small coin-
| tossing demo in Python that demonstrates what I mean, I'm
| definitely not the best explainer!
| fairity wrote:
| I'd love to see the winrate data for Stockfish against Stockfish,
| for each data set. To get a sense of what the objective winrate
| is.
| queuebert wrote:
| Once a computer gets to an advantage of +/-1.0 or so, the win
| is virtually assured in all positions, barring a few weird
| theoretical draws and misevaluations of the score of the
| position (e.g. closed positions with no way to make progress),
| although the latter problem has gotten a lot better with NN
| engines.
|
| (I used to play computer correspondence chess.)
|
| Edit: I should add that +/-1.0 is roughly a pawn's worth of
| material. So a computer up a knight or bishop -- nominally 3
| points of material -- should virtually always win.
| d_burfoot wrote:
| This thread makes me want to build a simple chess-practice tool
| that works like this: 1) Get a big database of positions
|
| 2) Use StockFish to evaluate all the positions
|
| 3) Pick a position at random, show it to the user, and ask for
| their evaluation
|
| 4) User gets a score based on the difference b/t their eval and
| StockFish's.
|
| The idea being that this could allow you to rapidly hone your
| position-evaluation skill. That might be a faster way to improve
| at chess than just grinding through many games.
| swader999 wrote:
| Chess engines already do this.
| JHonaker wrote:
| The problem I see with this is that it's not very useful for
| people to know if something is a +3 or +4.1 position. The
| qualitative descriptions that underlie that rating is what's
| important. How does my pawn structure compare to my opponents?
| What is the balance of minor pieces (knight and knight vs
| bishop knight, BB vs KK, etc.)? That's how you get to
| understand chess.
| EchoAce wrote:
| Yeah, this is probably better for a game like Go where
| evaluating raw point differentials is a common thing that
| professionals (and even strong amateurs) do.
| ginnungagap wrote:
| A guy on reddit made a website that does exactly that, but I
| cannot find anymore at the moment
| rmetzler wrote:
| I just play often 10min games on lichess, then look at all the
| mistakes I made and try to memorize simple rules of thumb for
| better moves.
| POiNTx wrote:
| Sort of like this (but without guessing the best move):
|
| https://makotoe.github.io/guess-the-eval/
| disambiguation wrote:
| like this? https://lichess.org/training
| frakt0x90 wrote:
| Not to rain on your fun, but this already exists. I watched
| Hikaru Nakamura play it online once. It just gives a random
| position and you have to guess the centipawn loss of the
| position. Kinda like Geoguessr for chess.
| whoisthis12 wrote:
| Do you know what the site is?
| ebiester wrote:
| Stockfish eval is often misleading because some positions are
| very sharp - if you see mate in 15 you're ahead, but otherwise
| you're far behind at the most pathological case.
| shawabawa3 wrote:
| You could do some basic filtering on e.g. top 3 moves are all
| within 0.5 or something
| 6D794163636F756 wrote:
| I think the problem then is a position where there is only
| one winning move that is 8+moves away. If one is mate in 10
| and the others are mate in 3 for your opponent how do you
| reconcile those into one evaluation?
| light_hue_1 wrote:
| There are endless tactics trainers out there.
|
| But it takes far more to build something useful for humans than
| just asking stockfish to give you the best move.
|
| For one thing you don't want to learn to play like machines.
| Often the moves that machines make are terrible human moves.
| Machines walk into extremely dangerous positions all the time;
| positions where you need to make a series of only moves to gain
| a small advantage. Humans shouldn't be doing this.
|
| Machines also rely on tactics heavily. Unless you understand
| the tactics in play it will make your play much worse. It might
| appear to you take a piece can't be taken, but stockfish says
| it can. Ok? Unless you understand the reason why, you aren't
| going to gain anything from this exercise.
| TechBro8615 wrote:
| I wonder how true this will be over the next decade or so
| when the top humans are people who have trained with machines
| their whole career.
| billfruit wrote:
| "1200 Elo players don't know how to take advantage of having the
| bishop pair."
|
| How exactly does one take advantage of having a bishop pair? Why
| is that not obvious to players under 1200?
| wonnor wrote:
| Generally the advantage of a bishop over a knight is its
| increased mobility. The bishop pair is more mobile than N+N or
| B+N and can control both color complexes. To exploit the
| mobility advantage, good players tend to try to "open up" the
| position more to increase the scope of the bishops. A classic
| example of a strategic goal if you want to play for an open
| position is to keep the pawn structure fluid (as opposed to
| locked up), which can be too subtle for weaker players.
| red_admiral wrote:
| I'm surprised that in the higher ELO ranges, being up a clean
| pawn has only a comparatively minor impact - I thought that one
| clean pawn ahead and no other major positional or structural
| disadvantages was more or less "GG" among top players.
| tux1968 wrote:
| Just a friendly pedantic point, it's "Elo", not "ELO". Rather
| than an acronym, it's a person's name; that being the rating
| system creator, Arpad Elo.
| xxs wrote:
| For years the guy calculated the FIDE ratings by hand...
| Olipro wrote:
| If you want to be fully pedantic, it's Elo, not Elo - the way
| in which you pronounce the former is dramatically different
| from the latter.
| neaden wrote:
| if you want to be fully fully pedantic its Glicko-2 rating
| system on Lichess, while FIDE uses Elo.
| digging wrote:
| Rather, players have a FIDE rating within FIDE, and a
| unique rating in each system, because no organization
| follows the exact, original Elo system.
| shawabawa3 wrote:
| To be correctly pedantic, it's named after Elo but it is
| called the Elo rating system
| zeteo wrote:
| You are correct, but this uses Lichess ratings, which are a bit
| inflated, and probably a variety of time controls including
| blitz. At levels of play below super-grandmaster with full time
| control the accuracy of play can be rather low, and picking a
| suboptimal move will often cost you half a pawn (or more) in
| engine evaluation. Add this up over an entire game and a one
| pawn advantage is easily lost in the variability of both
| players making compounding errors.
| [deleted]
| erostrate wrote:
| I suspect the author only counts raw material. So players who
| lose a pawn but gain compensation reduce the perceived impact
| of losing a pawn. Including many openings where you temporarily
| give up a pawn (queen's gambit, benko, etc).
| nomilk wrote:
| I was thinking the same. It could be true for higher ELO
| players being down a pawn is a good thing, since your
| opponent took the bait.
| yuvadam wrote:
| Many pawn-up endgames are still technically a draw (king and
| pawn vs. king [1] in the most extreme example)
|
| [1] -
| https://en.wikipedia.org/wiki/King_and_pawn_versus_king_endg...
| xxs wrote:
| That depends both on the position of the pawn and the king...
| smatija wrote:
| Take care that not all of king and pawn versus king are
| drawn. Their result depends on relative position of kings.
|
| Nice example of more extreme imbalance is that sometimes
| King+Queen vs King+Pawn is drawn - that is when pawn is on
| seventh rank of bishop or rook file with defending king in
| front of it, while attacking king is not close enough to
| force checkmate.
|
| See: https://en.wikipedia.org/wiki/Queen_versus_pawn_endgame#
| Quee...
| mtlmtlmtlmtl wrote:
| Yeah. More commonly rook endings are notoriously hard to win.
|
| I gained a lot of rating once I started really studying the
| ins and outs of all the different rook and pawn vs rook
| endings. Because no matter what the tablebase might say, you
| have to be very precise with or without the pawn.
|
| So I started getting a lot of wins out of equal positions,
| and got a lot better at saving a draw in bad positions.
|
| Pawn and minor piece vs minor piece is also fraught with
| drawing chances, especially with bishops. Because you can
| just sac the piece for the pawn and there's insufficient
| material for mate.
|
| Queen and pawn vs queen is basically a 3 result game at the
| club level. So many ways to blunder your queen. And at GM
| level it tends towards a draw I think. Though it's so
| stupidly complicated I never even tried to properly study it.
| littlestymaar wrote:
| > Yeah. More commonly rook endings are notoriously hard to
| win.
|
| Oh, so it's not just me.
| mtlmtlmtlmtl wrote:
| There's a famous saying in chess: "all rook endings are
| drawn".
|
| Of course, this isn't actually true. But it's a useful
| rule of thumb to just assume it's a draw unless you're
| sure it's a win, because it probably is, fucking somehow.
| wmsiler wrote:
| I wonder how this would change if you only looked at highly rated
| chess engines. For example, is a rook pair really not as good as
| a queen or is it just that _humans_ aren't as good at using the
| rooks effectively?
| KingOfCoders wrote:
| Really nice insights.
|
| Though
|
| "Even at lower Elo ranges like 1200-1400, you're 4-5% more likely
| to win if you have the only bishop pair. 1200 Elo players don't
| know how to take advantage of having the bishop pair, and yet it
| helps them win all the same [...] A 1000-1200 Elo player is only
| about 8% more likely to win when up two minors for a rook."
| tech_ken wrote:
| Maybe I'm just a choke artist but if I win the exchange I'm
| probably losing the game. Opponent always seems to "turn on" and
| I just get blown away
| rauljara wrote:
| Honestly, two rooks for a queen being a disadvantage is kind of a
| relief.
|
| I've always been taught the two rooks are better and who can
| argue with 5 + 5 > 9? But also, I've also lost almost every game
| where I've had the rooks. I always thought that I just needed to
| be a better player to take advantage of it. Glad to know it
| wasn't just me.
|
| Just goes to show that these shortcuts, like the point system,
| are only heuristics, and pretty shallow ones at that. Knowing
| that being up a bishop gives you slightly more of an advantage
| than a knight is better than nothing. But learning in which sorts
| of positions a knight is actually better than a bishop will give
| you a much deeper understanding (and correspondingly more wins).
| mtlmtlmtlmtl wrote:
| Yeah, agreed. 2 rooks vs queen is much easier to play for the
| queen in most cases, I've found.
|
| The queen can be good as a single piece whereas the rooks have
| to coordinate, which is hard when there's a queen on the board
| ready to fork. Often the rooks end up having to defend
| eachother, and if this happens suboptimally they can become
| very immobilised on a useless file or rank whereas the queen
| can fly around the board attacking stuff at will.
|
| Like you said, material imbalance is very difficult to evaluate
| and understand. I generally recommend not to incorporate them
| into one's play until ~1700 FIDE elo. Though sometimes you're
| forced into it of course.
|
| It's also a matter of style. I personally love materially
| imbalanced positions, and I'm pretty good at them, so I
| incorporate a fair bit of exchange sacrifices into my play.
| Because then I often get positions I understand better than my
| opponent and that makes up for the material on its own, I find.
|
| But other players just prefer a different style of play and
| maybe shouldn't go for it even if objectively it's the best
| move, because they'll end up misplaying the position.
| Enginerrrd wrote:
| As someone low in rating, there are few things in chess more
| satisfying to me than when the engine confirms I was correct
| in sacrificing an exchange or a full piece for some sort of
| positional advantage. The opportunity itself comes up very
| rarely for me, so recognizing it just makes me giddy.
| mtlmtlmtlmtl wrote:
| Yeah, there's nothing that feels better in chess than that.
| I still remember my first win in the norwegian
| championships(in the noob category, not bragging, they let
| anyone play in it) almost 20 years ago(yikes); found,
| correctly calculated and played a rook sacrifice leading to
| mate(it was like a 3 move combination, all checks, nothing
| too fancy but I did consciously threaten it the move
| before). I also remember walking into mate in 1 in another
| game that tournament, the rest is a blur.
|
| And in fact most of the wins I remember the most clearly
| involved some kind of well-found sacrifice. The others tend
| to blend together too much in my mind. And most of the
| losses I remember most clearly involved horrible blunders.
| superhuzza wrote:
| edit: my comment was silly, removed.
| jpmoral wrote:
| I don't think being up a full piece counts as material
| imbalance.
| superhuzza wrote:
| You are absolutely right, I deleted my comment as it was
| misleading.
| theonemind wrote:
| The pieces definitely vary in value by position. Chess engines
| that people have no chances of beating will occasionally
| sacrifice a rook to take an enemy knight on a good outpost
| square (past ability to get attacked by enemy pawns and
| attacking enemy space). Hard to argue they don't know what
| they're doing when they can beat all humans.
| im3w1l wrote:
| The author doesn't list which time control he studied (maybe a
| mishmash of bullet, blitz and rapid?), but I'm thinking that
| shorter time controls favor the queen.
| alexmolas wrote:
| Nice article!!
|
| But this is not what you're testing. You're not determining the
| effect of imbalance alone, but imbalance + particular position of
| pieces. To determine the effect of imbalance you should study how
| does not having a certain piece since the beginning affect the
| result of the game.
|
| Also, being a pawn up in the opening is much more different than
| being a pawn up in the end game. It would be interesting to redo
| this analysis but splitting by opening, middle game, and end
| game.
| moi2388 wrote:
| If you take into account all variables aren't you just writing
| a chess engine at that point?
| jackmott42 wrote:
| I am amazed that you think the author doesn't already
| understand that.
| alexmolas wrote:
| Well, I don't know if the author understands that or not, but
| I guess they do. I'm just pointing to the fact that the
| analysis can be misleading, and I just shared a proposal that
| I think it would make it more interesting :)
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