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

Re: When Grandmasters Blunder: Even the best make mistakes

#41

Post by dfan » Tue, Feb 17, 2015, 12:45 PM 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…

Yes, I know how computer evaluations work. The fact that they take positional as well as material considerations into play doesn't change the point, which is that playing a +5 sure-win move instead of a +8 sure-win move is not a horrific magnitude-3 blunder the way that playing a -2 move instead of a +1 move is, whatever your units of magnitude are, because what really matters is the change in the expected result of the game.

Re: When Grandmasters Blunder: Even the best make mistakes

#42

Post by Igglyboo » Tue, Feb 17, 2015, 2:25 PM 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 agree that they are probably not independent, but I have a different idea as to why. From my personal experience of playing many competitive games, when your opponent makes an obvious mistake you might get too excited or carried away about capitalizing on the mistake and make a subpar move. Consider a situation like this:

"Wow he just left his queen right open! I can't believe he did that! I'll take it with my rook."

Rook takes queen, rook is wide open, could have taken queen with some other piece and had it protected.

It's possible this doesn't apply to chess as much but in more fast paced games if you see an opening, you take it, because even if you don't capitalize 100% on it you're better off than not doing anything about the blunder.

Re: When Grandmasters Blunder: Even the best make mistakes

#43

Post by paulftw » Tue, Feb 17, 2015, 2:45 PM UTC

OK, so they've analyzed 4.9 million moves. How many double blunders did they find in the set? If the hypothesis of independent events is true there should be about (4.9e6 / 10,000) = 490 doubles in the data set. An obvious way to test accuracy of the model is to compare that to the actual number.

Why hasn't that comparison been done/mentioned?

Re: When Grandmasters Blunder: Even the best make mistakes

#44

Post by sprkyco » Tue, Feb 17, 2015, 3:24 PM UTC

Not relevant to chess, but in Japanese there is a saying: saru mo kikara ochiru. Not sure if I spaced that correctly but it amounts to "Even monkeys fall from trees"

Re: When Grandmasters Blunder: Even the best make mistakes

#45

Post by fsk » Wed, Feb 18, 2015, 12:55 AM UTC

hudibras wrote: post #36

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.

Some of the rules are awkward and confusing to someone who doesn't understand them.

For example, you can convey information to your partner, based on how long you take to bid. Technically, you aren't allowed to have that information.

Me - Left Opponent - Partner - Right Opponent

1NT - x - xx - pass

pass - 2C (after long pause) - x - pass (after long pause)

pass - 2D

Explaining:

I played a weak 12-14 HCP NoTrump opening

opponent on my left doubled, showing a good hand

my partner redoubled, saying he also has a good hand (i.e., we got them now)

Rather than letting us make 1NT redoubled, the opponent on the left ran out to 2 Clubs.

My partner doubled, because he had good clubs (i.e., we got them).

The opponent on the right passed, but he waited a long time before passing, illegally conveying to his partner that he was not sure if they should stay in 2 Clubs or run.

Taking advantage of that (illegally obtained) information, the opponent on the left decided to run to 2 Diamonds.

So, someone who does not understand the concept of unauthorized information would not understand why I would be disadvantaged.

At a local club game, I would let it slide. At a regional tournament, I'd expect the director to get it right.