When Grandmasters Blunder: Even the best make mistakes • Hacker News Board

Re: When Grandmasters Blunder: Even the best make mistakes

#31

Post by verteu » Tue, Feb 17, 2015, 4:41 AM UTC

jdoliner wrote: post #19

verteu wrote: post #18

> Due to cost limitations we had to limit crafty to 2 seconds of analysis time per move A grandmaster with standard time controls could defeat a 2-second limited Crafty. So how do you know you're finding true blunders, and not simply positions that the engine evaluates incorrectly?

This is definitely the biggest limitation of our approach right now and there are certainly some things that we counted as blunders that aren't true blunders. We're working on rectifying this by doing another pass with a better engine and more time to analyze. That said we tested this on a smaller set of games by comparing it to results from better engines and found that only a very small number of moves tricked craf…

Thanks the response -- I really enjoyed your article.

The results of the cross-validation you mentioned would be interesting as well.

Re: When Grandmasters Blunder: Even the best make mistakes

#32

Post by jdoliner » Tue, Feb 17, 2015, 4:55 AM UTC

komaromy wrote: post #23

stolio wrote: post #12

Earlier quoted context omitted.

What time controls were you looking at? I'm half-jokingly wondering if the big dip of correct moves in the upper 2800 range is Nakamura's crazy opening style :) (He's rated upper 2800's in blitz and rapid)

My guess: the only one that has been rated in that bucket in the last year was Caruana, post-Saint Louis. At that point, he suffered (and is still going through) a big decline with several bad blunders.

This was the leading hypothesis on r/chess. I'm pretty sure it's right Naka didn't hit this rating in 2014 as far as I know.

Re: When Grandmasters Blunder: Even the best make mistakes

#33

Post by gamegoblin » Tue, Feb 17, 2015, 5:00 AM UTC

dfan wrote: post #24

Using "number of pawns of evaluation lost" as a proxy for the severity of the blunder has some fundamental problems. The main one is that the relationship between evaluation in "pawns" and expected result (expected value of the game result, from 0 to 1) is not linear. (It couldn't be, since one of them maxes out at one.) It's actually more of a sigmoid curve. This means that a player may easily make a horrific "3-paw…

Somewhat agreed. I'm a decent-ish amateur player and if I'm playing bullet or blitz chess with very low time left on the clock (<10 seconds), and its king pawn vs king ending and I'm about to convert my pawn, I will almost always choose to under promote to a rook instead of promoting to a queen because I am 100% sure I can mechanically checkmate my opponent without accidentally stalemating (due to a blunder under extreme time pressure) while spending virtually no clock time. I could almost certainly do it with a queen, but it's for my own peace of mind that I use a rook instead. Safe and easy victory, but it'd count as a blunder.

Re: When Grandmasters Blunder: Even the best make mistakes

#34

Post by komaromy » Tue, Feb 17, 2015, 5:01 AM UTC

jdoliner wrote: post #32

komaromy wrote: post #23

Earlier quoted context omitted.

My guess: the only one that has been rated in that bucket in the last year was Caruana, post-Saint Louis. At that point, he suffered (and is still going through) a big decline with several bad blunders.

This was the leading hypothesis on r/chess. I'm pretty sure it's right Naka didn't hit this rating in 2014 as far as I know.

The only other candidate would be Carlsen when he dipped to the high 2850s.

Re: When Grandmasters Blunder: Even the best make mistakes

#35

Post by Someone » Tue, Feb 17, 2015, 7:31 AM UTC

mcherm wrote: post #16

It seems to me that the article overlooks one glaringly obvious issue: that the two blunders may not be independent events. In this case, it seems quite likely that the second player's blunder was made much more likely by the fact that the first player had just blundered. To be more specific, white moved the king which appeared (at first glance) to prevent black from using a check threat to attack white's rook. The b…

"He assumed that such a top-level player would never make such a mistake"

But if top-level players make such mistakes in about 1% of their moves, that assumption is utterly wrong (1% per move translates to (ballpark) once in every five games that an similarly ranked opponent essentially gives you victory, if you yourself manage not to blunder), so one could call making the assumption a blunder.

Re: When Grandmasters Blunder: Even the best make mistakes

#36

Post by hudibras » Tue, Feb 17, 2015, 7:47 AM UTC

fsk wrote: post #8

One thing I know from playing serious Bridge: An expert player makes far fewer mistakes than the average player. He does not make zero mistakes. I read one tournament report, where an expert player revoked. When an expert plays good or average players, he does not need to be brilliant to win. He just has to play competently, and wait for his opponents to make mistakes.

A revoke at a bridge tournament is the closest thing to a crime scene that I've ever seen. I half-expected the tournament directors to cordon off the table in yellow plastic tape while they recreated what happened.

Re: When Grandmasters Blunder: Even the best make mistakes

#37

Post by iwwr » Tue, Feb 17, 2015, 10:05 AM UTC

dfan wrote: post #24

Using "number of pawns of evaluation lost" as a proxy for the severity of the blunder has some fundamental problems. The main one is that the relationship between evaluation in "pawns" and expected result (expected value of the game result, from 0 to 1) is not linear. (It couldn't be, since one of them maxes out at one.) It's actually more of a sigmoid curve. This means that a player may easily make a horrific "3-paw…

Nope, "number of pawns" is only a notional number, it's a score calculated by a chess engine. Being 1 pawn ahead may just mean a particular position where one side has an equivalent advantage though not necessarily being a physical pawn ahead. Another aspect is sometimes you're a physical pawn short, but the position evaluation may only show -0.3 pawns against you, meaning you've got positional or counter-play advantages to compensate. Often players will sacrifice pieces for counter-play and activity.

Chess engines also implement a heuristic called 'contempt' where they may make a sacrifice in order to avoid a drawn position, when faced with an inferior opponent.

Re: When Grandmasters Blunder: Even the best make mistakes

#38

Post by sogjis » Tue, Feb 17, 2015, 10:52 AM UTC

What exactly is blunder? Watch this game: http://www.chessgames.com/perl/chessgame?gid=1032537

Tal sacrificed horse and queen.

Re: When Grandmasters Blunder: Even the best make mistakes

#39

Post by sireat » Tue, Feb 17, 2015, 11:25 AM UTC

mcherm wrote: post #16

It seems to me that the article overlooks one glaringly obvious issue: that the two blunders may not be independent events. In this case, it seems quite likely that the second player's blunder was made much more likely by the fact that the first player had just blundered. To be more specific, white moved the king which appeared (at first glance) to prevent black from using a check threat to attack white's rook. The b…

I was expecting the article to focus on this and dis/prove hypothesis of double blunder.

Most top players would comment (as Anand and Carlsen did after the game) that double blunders are relatively common in top level play.

Here is one famous case: http://www.chess.com/article/view/the-amazing-chess-illusion

In my personal experience this has been common too, when I mix playing against 2500 players and 1900 players in blitz (I am 2350fide), it is relatively easy to skip over simple hanging pieces for a move or two.

In a regular tournament game it has happened a few times as well (one player commiting a gross blunder and other not noticing).

The big question whether it is out of ordinary statistically speaking.

Re: When Grandmasters Blunder: Even the best make mistakes

#40

Post by rockdoe » Tue, Feb 17, 2015, 11:53 AM UTC

iwwr wrote: post #37

dfan wrote: post #24

Using "number of pawns of evaluation lost" as a proxy for the severity of the blunder has some fundamental problems. The main one is that the relationship between evaluation in "pawns" and expected result (expected value of the game result, from 0 to 1) is not linear. (It couldn't be, since one of them maxes out at one.) It's actually more of a sigmoid curve. This means that a player may easily make a horrific "3-paw…

Nope, "number of pawns" is only a notional number, it's a score calculated by a chess engine. Being 1 pawn ahead may just mean a particular position where one side has an equivalent advantage though not necessarily being a physical pawn ahead. Another aspect is sometimes you're a physical pawn short, but the position evaluation may only show -0.3 pawns against you, meaning you've got positional or counter-play advant…

Your response has absolutely nothing to do with the point the parent poster makes and completely and utterly misses the point.

He is arguing that "percentage of winning" is not linearly related to "pawn or equivalent advantage". That has got nothing to do with whether those pawns are physical ones or positional advantages that have equivalent value.