Re: [computer-go] Anchor Player
Are you sure about this? Here is what I've seen on Wikipedia but I've also seen this before from other sources: Another departure from tradition is that ELO ratings are calibrated by winning percentage, not by stone handicaps. An extra handicap stone has much less influence on winning percentage at a low level of play than at a high level of play. Therefore, from the perspective of ELO ratings, traditional ranks are too spread out at the low level and too compressed at a high level. To put it another way, a 6-dan player has a much better chance of beating a 5-dan player than a 15-kyu player has of beating a 16-kyu player, so the ELO system must conclude either that the top players need to be further apart in rating than 100 points, or the bottom players need to be closer in rating than 100 points. - Don On Mon, 2006-12-25 at 20:23 +0100, Andrés Domínguez wrote: > 2006/12/25, Don Dailey <[EMAIL PROTECTED]>: > > > > On Sun, 2006-12-24 at 13:54 -0800, David Fotland wrote: > > > There is no fixed relationship between ELO and handicap stones. Stronger > > > players have less variation in their play, so a handicap stone is worth > > > more > > > ELO points for a stronger player than a weaker player. > > > > What you say is consistent with what I've heard from other sources. > > > > My understanding is that in ELO terms the ranks are compressed at the > > higher levels and spread out at lower levels. So there is less > > difference between 4 dan and 5 dan than 15 kyu and 16 kyu for > > instance. > > I think it's exactly the opposite. The difference between 4 dan and 5 dan is > one stone, but more ELO than between 15 and 16k (also one stone). > > Andrés ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Anchor Player
2006/12/25, Don Dailey <[EMAIL PROTECTED]>: On Sun, 2006-12-24 at 13:54 -0800, David Fotland wrote: > There is no fixed relationship between ELO and handicap stones. Stronger > players have less variation in their play, so a handicap stone is worth more > ELO points for a stronger player than a weaker player. What you say is consistent with what I've heard from other sources. My understanding is that in ELO terms the ranks are compressed at the higher levels and spread out at lower levels. So there is less difference between 4 dan and 5 dan than 15 kyu and 16 kyu for instance. I think it's exactly the opposite. The difference between 4 dan and 5 dan is one stone, but more ELO than between 15 and 16k (also one stone). Andrés ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Anchor Player
I was always taught in Chess to play the board, not the player. But in principle this is wrong if your goal is to increase your chances of winning the game. The problem with playing your opponent is that if you don't know the proper technique for doing this, it will distract you from the real game.For weaker players, it's enough to just "play the board", anything beyond this will hurt their play. What most people don't understand is that playing your opponent doesn't mean that you suddenly start playing risky unsound moves. Playing your opponent is a very careful and controlled process that should not involve a radical change of playing style. It involves waiting for mistakes, not making them. You will try to encourage these mistakes, but not at great risk to yourself. Also, you must never underestimate your weaker opponent. I mention this because there have been a few posts that imply that you should play normally, change nothing, and just wait for the mistake. In fact, this is almost correct, most of the moves should be like this.If you don't know what you are doing ALL the moves should be like this. But if you want to actually maximize your winning chances, you need to be more sophisticated than this. At least this applies in Chess. I'm sure this must apply to GO too. When books and experts say "don't play the opponent" they are giving beginner advice. Most beginners can't handle this. It should be done in very carefully measured ways.It's obviously counter-productive to start playing high risk moves and throw soundness out the window.But that doesn't mean there is nothing you can do to take advantage of a weaker opponent in a losing position. For most people, the advice to "just play the board" is going to protect them. Playing the opponent is a skill and weaker (chess players) screw up big time when attempting to do this. I'll give one example from chess: What do you do when your opponent is in time-trouble? How do you "play the opponent" and capitalize on this? The knee-jerk reaction is to play extra quickly, to deprive him of thinking on your time. This is foolish. Your opponent will be at his best with the extra adrenaline kick. If you play fast you will be at your worst. The adrenaline rush will wear out your opponent, so in such a situation it is better to play normally or even EXTRA SLOW. In fact, if I see my opponent is excited, I take my sweet time, forcing him to stay at attention a very long time. If I have a choice between complicated and simple positions, I take the complicated position IF and ONLY IF I am totally comfortable with it. After all I have more time to figure it out. I won't play unsoundly just to get a complicated position though. The better players are not really that handicapped when under time pressure - they remain highly focused and do not let themselves get too excited - no point in helping them along with rash moves.YOU are the one that must remain calm and stay 100 percent focused. I did not have to lose very many games that way to figure this out. There are many other ways to take advantage of your opponent in chess that I consider sound if applied in a very measured and careful way. None of them call for making truly unsound moves, especially when you consider that in a losing position, all moves are unsound in some sense.Now you are in a situation of "risk management", you are looking for moves that give you the best chances of winning (a lost game) and usually, it requires a move that makes it the most difficult for your opponent. This is not quite the same as moves that make it easiest for you, which is what you look for in WON positions. Weaker players cannot do this. They are best just sticking with the style that is most comfortable for them. - Don On Mon, 2006-12-25 at 15:23 +, Vlad Dumitrescu wrote: > On 12/25/06, Jacques Basaldúa <[EMAIL PROTECTED]> wrote: > > Hideki Kato wrote: > > Nevertheless, I have certain experience (not with > > MC) of computer go with handicap and I can tell: > > Waiting for the opponent to blunder is only a good > > strategy if the handicap is lower than it should. > > E.g. 7 kyu difference & Handi 3. If the handicap > > approaches its real value, that does not work. > > I have seen (many times) GnuGo not being able to > > win a H7 game to an opponent more than 10 kyu > > weaker. That happens because it had to invade > > unclear positions. The more the invasion is > > postponed, the worse. The weaker player simply > > does defensive uninteresting play and so does the > > stronger player (with better yose, but that's not > > enough). If I (manually) use two or three turns > > just to invade, GnuGo tries to save the invading > > stones and that's more than enough to win the game. > > Hi, > > This depends on your definitions. If the position is unclear and GnuGo > doesn't invade, then I'd
Re: [computer-go] Anchor Player
Hi Hideki, I think what I will do is use ELO and a simple formula for determining handicap. The formula will impose a slight curve on the value of a handicap stone, it will slightly increase with each ELO point. In other words a stronger player will benefit more from having an extra stone and the handicap will be chosen appropriately. Of course the formula will be an assumption. I will either build something in to the server to make gentle modifications over time, or I will manually adjust the parameters from time to time based on the data collected from the server. It will be easy to tell if the handicaps are too aggressive or too conservative after a lot of data is collected. The initial formula will assume the stronger players on 19x19 CGOS need 1 handicap stone to overcome 100 ELO points. This seems to be fairly standard in servers and I think it's probably a good starting point.Since computer programs do not represent very strong players at 19x19 I don't think there is a great deal of "rank compression" at these levels, so I can imagine that this will be a reasonable starting point for the stronger players. Of course 100 ELO per stone will probably not work well with the really weak players (and may even be wrong for the strong computer players) so one way or another we will have to converge on a formula that tries to be as fair as possible. There seems to be a large range of computer playing skill on CGOS, from zero ELO to 2200 without any large gaps.This may look different at 19x19, we shall see. I think our formula will require 2 constants that can be adjusted to control the shape of the curve. I will come up with something but I will be happy to take suggestions too. Like everything else that has to do with ratings, rankings, handicaps, etc this is all an estimate and will never be 100% perfect. But I think we can make the attempt to fit the data according to the results to be as fair as possible. - Don On Mon, 2006-12-25 at 14:35 +, Jacques Basaldúa wrote: > Hideki Kato wrote: > > > In Nihon Kiin's ELO system(1), 1000 ELO is 1 rank, > > The Elo rating is based on two assumptions: > > a. The performance of each player in each game is a >normally distributed random variable. > b. All players performance have the same standard >deviation. (This is controversial, and other >rating systems modify this.) > > Anything else is arbitrary! Including how many Elo > points produce a given probability. > > Elo *tradition* (from chess) has always used the > convention: > > 100 points = 1/(1+10^.25) = 0.3599 approx = 1/3 > 200 points = 1/(1+10^.50) = 0.3204 approx = 1/4 > > 1000 Elo points give a probability of 1/317 > > It is obvious that Nihon Kiin's use a different > scale (may be 1000 Nihon Kiin's = 100 traditional). > > On the handicap subject: > > I am very happy to have a 19x19 server either with > or without handicap, so I welcome it as it is. > > Nevertheless, I have certain experience (not with > MC) of computer go with handicap and I can tell: > Waiting for the opponent to blunder is only a good > strategy if the handicap is lower than it should. > E.g. 7 kyu difference & Handi 3. If the handicap > approaches its real value, that does not work. > I have seen (many times) GnuGo not being able to > win a H7 game to an opponent more than 10 kyu > weaker. That happens because it had to invade > unclear positions. The more the invasion is > postponed, the worse. The weaker player simply > does defensive uninteresting play and so does the > stronger player (with better yose, but that's not > enough). If I (manually) use two or three turns > just to invade, GnuGo tries to save the invading > stones and that's more than enough to win the game. > > As I said before, its a different game and the > more accurate you determine the handicap, the > worse. If at all, handicap should always be > underestimated by a factor of 1/2. > > Handicap is used to make the game interesting > enough to white (but usually white still wins) > to honor a lower player with a learning game. > I hope weaker bots will learn at lot from the > games played against the stronger. ;-) > > Jacques. > > > ___ > computer-go mailing list > computer-go@computer-go.org > http://www.computer-go.org/mailman/listinfo/computer-go/ ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Anchor Player
On 12/25/06, Jacques Basaldúa <[EMAIL PROTECTED]> wrote: Hideki Kato wrote: Nevertheless, I have certain experience (not with MC) of computer go with handicap and I can tell: Waiting for the opponent to blunder is only a good strategy if the handicap is lower than it should. E.g. 7 kyu difference & Handi 3. If the handicap approaches its real value, that does not work. I have seen (many times) GnuGo not being able to win a H7 game to an opponent more than 10 kyu weaker. That happens because it had to invade unclear positions. The more the invasion is postponed, the worse. The weaker player simply does defensive uninteresting play and so does the stronger player (with better yose, but that's not enough). If I (manually) use two or three turns just to invade, GnuGo tries to save the invading stones and that's more than enough to win the game. Hi, This depends on your definitions. If the position is unclear and GnuGo doesn't invade, then I'd say *that* is a blunder (especially when being behind). The idea is to play the best move available, and let the weaker player make suboptimal ones -- in the end, if the handicap is correct, the net result should be zero and the result would be the same as in an even game with an equal partner. The best move may be a somewhat risky invasion - of course one has to assume the partner will not play perfectly, but everybody does that every time anyway, right? Otherwise nobody would have any hope to win and so nobody would play ;-) best regards, Vlad ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
Re: [computer-go] Anchor Player
Hideki Kato wrote: In Nihon Kiin's ELO system(1), 1000 ELO is 1 rank, The Elo rating is based on two assumptions: a. The performance of each player in each game is a normally distributed random variable. b. All players performance have the same standard deviation. (This is controversial, and other rating systems modify this.) Anything else is arbitrary! Including how many Elo points produce a given probability. Elo *tradition* (from chess) has always used the convention: 100 points = 1/(1+10^.25) = 0.3599 approx = 1/3 200 points = 1/(1+10^.50) = 0.3204 approx = 1/4 1000 Elo points give a probability of 1/317 It is obvious that Nihon Kiin's use a different scale (may be 1000 Nihon Kiin's = 100 traditional). On the handicap subject: I am very happy to have a 19x19 server either with or without handicap, so I welcome it as it is. Nevertheless, I have certain experience (not with MC) of computer go with handicap and I can tell: Waiting for the opponent to blunder is only a good strategy if the handicap is lower than it should. E.g. 7 kyu difference & Handi 3. If the handicap approaches its real value, that does not work. I have seen (many times) GnuGo not being able to win a H7 game to an opponent more than 10 kyu weaker. That happens because it had to invade unclear positions. The more the invasion is postponed, the worse. The weaker player simply does defensive uninteresting play and so does the stronger player (with better yose, but that's not enough). If I (manually) use two or three turns just to invade, GnuGo tries to save the invading stones and that's more than enough to win the game. As I said before, its a different game and the more accurate you determine the handicap, the worse. If at all, handicap should always be underestimated by a factor of 1/2. Handicap is used to make the game interesting enough to white (but usually white still wins) to honor a lower player with a learning game. I hope weaker bots will learn at lot from the games played against the stronger. ;-) Jacques. ___ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
