Life In 19x19

Handicapping in Tournaments
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Author:  BlindGroup [ Sun Apr 23, 2017 7:11 am ]
Post subject:  Handicapping in Tournaments

My local club just held a tournament this weekend. When chatting with the person who was generous enough to organize everything, he mentioned that the pairings were set to "handicap minus one". I might have the terminology wrong, but I think the idea was that the handicap was set as one less than the difference in ranks. Any game between players within one rank of each other would be even, and if the difference was 2 or more, the handicap would be the difference minus one. So, 5k v 8k would yield a 2 stone handicap.

Two questions:

1. Do I have this right?

2. What is the logic of using this system? Why not just use the actual handicaps? As long as everyone is equally likely to play both weaker and stronger players no one is disadvantaged at the level of the tournament. However, it seems like there are two issues:

(a.) the weaker (stronger) player faces a disadvantage (advantage) in any individual game.

(b.) to ensure that every player actually has an equal number of strong and weak opponents, there needs to be both a large number of rounds and a large number of players, no?

Author:  alphaville [ Sun Apr 23, 2017 11:49 am ]
Post subject:  Re: Handicapping in Tournaments

BlindGroup wrote:
My local club just held a tournament this weekend. When chatting with the person who was generous enough to organize everything, he mentioned that the pairings were set to "handicap minus one".

I have seen this system too, it is not something peculiar for your local club.
First of all: any tournament using handicap is "just for fun" nowadays, it is meant to popularize the game and get more people to come to the club and play, not meant as serious/official competitive go. So as long as it achieves this goal, it is fine.

Why handicap-1? Because handicaps and kyu/dan levels are not one-to-one. Probably, using full handicap you will have the stronger players lose more, which is not a nice outcome given that they "do a favor" to the weaker player by giving them handicap, to start with.

I don't see "-1" as a perfect system, but I can see some reasons for it.

Author:  BlindGroup [ Sun Apr 23, 2017 12:46 pm ]
Post subject:  Re: Handicapping in Tournaments

alphaville wrote:
I have seen this system too, it is not something peculiar for your local club.

The system was an option in the software used to do the pairings -- apparently, you can even go to "-2". So, it is definitely "standard" and not unique to our club. I'm also not opposed to it. I was just wondering what the considerations are for reducing the handicaps when does "-1" make more sense than "-2" or no adjustment.

Your suggestion that it benefits the stronger players was not born out. And logically, the strongest player is advantaged in all games, but everyone else has to at least play him at a disadvantage. So, it's not clear to me that this is a boon to the stronger players in general. Plus, I doubt that these players cared too much about winning at such a small tournament.

Author:  dfan [ Sun Apr 23, 2017 1:09 pm ]
Post subject:  Re: Handicapping in Tournaments

People regularly play at "handicap minus two" around here, and I like it. It creates more even games, which I like, and I am fine with giving the stronger player a bit of an advantage. (This may be partially due to my chess background, where it is a fact of life.)

One other non-obvious thing that it "fixes" has to do with the fact that in AGA tournaments people can generally enter at a stronger rank than their actual rating. Since this is popular, entering at your real rank can almost be like "playing down"; you are getting easier handicaps than you're really entitled to, and the AGA rating system isn't as impressed with your performance (if you care about that). This can lead to an inflationary behavior where everyone is implicitly encouraged to play up. Playing at handicap minus two mostly removes any concerns about that sort of thing; in a tournament of decent size, you'll just play 4 even games against people near your rank.

Author:  Pio2001 [ Sun Apr 23, 2017 1:44 pm ]
Post subject:  Re: Handicapping in Tournaments

In France, we use this system a lot.

Go is a game where each game can last more than two hours. That's a long time, compared to backgammon for example. If a tournament takes place during a week-end, usually, we can play 5 games and no more.

According to the pairing, some players may have no luck and have to play against strong opponents most of the time. Using handicaps allows to make the tournament an enjoyable experience for everyone even in this case.

Real handicaps are calculated so that there is an equal chance of winning from both players. That's why handicaps are reduced during tournaments. Otherwise, the strong players would have no more chance to win than any beginner, and the final rankings would make little sense.

In France, we use the software OpenGotha, written by Luc Vannier. By default, it does not use handicap for ranks above 1 dan. The handicaps are set according to the McMahon score rather than the rank, and since the McMahon floor is usually set to 20 kyu, it follows that players below 20 kyu play between them without handicap.
For example, a 9-dan playing versus a 1-dan will play with no handicap.
5 kyu vs 10 kyu = 4 stones handicap
20 kyu vs 30 kyu = no handicap.

If one of the players is above or below the bar, the handicap is calculated as if the player's ranking was equal to the bar.
15 kyu vs 30 kyu = 4 stones handicap (20-15-1)
9 dan vs 5 kyu = 4 stones handicap (1-(-4)-1)

It allows the dan players to compete seriously. And also, the handicap values are said to be inaccurate in the dan levels. So it may be better not to use them.

The effect on the rating used in France is a bit complicated. The rating variation of each player is multiplied by a coefficient equal to (1-H/10) where H is the handicap, except if the strongest player loses. In this case, his variation is again multiplied by (1-H/10).
It means that the games played with a handicap count less than the others. With 9 stones, the rating variation is ten times less than it would have been without handicap, and if white looses, his variation is one hundred times less (but his opponent's variation is still 10 times less).
Basically, strong players can't loose (many) points if they give handicap stones to their opponents.

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