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Handicap
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    Keywords: Go term

If two players differ in strength (see rank), the weaker player gets a handicap to compensate for the difference. That way, both players have a chance to win. In general, the ideal handicap is equal to the difference in kyu or dan ranks. Traditionally, handicap stones are placed on the star points, but one can also play with free placement of the handicap stones.

[Diagram]
The spots for the handicap stones

The traditional placement of handicap stones, from Black's viewpoint, is (see diagram):

  • One stone: The weaker player plays Black without komi
  • Two stones: ab
  • Three stones: abc
  • Four stones: abcd
  • Five stones: abcdi
  • Six stones: abcdef
  • Seven stones: abcdefi
  • Eight stones: abcdefgh
  • Nine stones: abcdefghi



Bill Spight: The traditional scheme gives an advantage to White. In an even game Black gives komi. If Black is 1 stone weaker, the proper handicap is for Black to put 2 stones and give komi. Alternatively, Black could play first and White could give komi, since komi is worth 1/2 stone. Simply having Black play first is inadequate compensation for the difference in strength.


Also, the equivalence between one stone and one rank is inexact. Is the fifth handicap stone worth the same as the fourth? However, through 9 stones the deviation appears to be quite small. This could be the topic of a good statistical study. :-)

Jasonred Gotta agree with this one. Not only that, but the size of the board has gotta make a difference too. IMHO, the strength of the players also makes a difference, as even 3 stones on a 19x19 is not much help to a 30 kyu, but is a HUGE difference to a 9 Dan... Especially if you're following French handicap, or whatever you call the "free placement of handicap stones" thing.

Instead of statistics though, I would ask a top Dan pro how much komi he'd be willing to give an equally strong opponent for a 1 stone handicap, for a 2 stone, and so forth.

I DO know that the 26th stone isn't worth as much as, say, the 5th stone... and on a 9x9, anything over 5 is probably a liability. More than 10 stones is just silly on a 9x9, you're just wasting your own territory, so I can safely say that the 10th stone should have a NEGATIVE value.


Dieter Verhofstadt: Let me get this straight:

A and B are of equal strength. A takes Black and B White. B gets 5,5 points of komi. Second game: B takes Black and A White. A gets 5,5 points of komi. We expect the same result. This means that the difference between having the first move or not is equivalent to 11 points. Removing komi is only worth 5.5 points. The next step we add a stone to Black's handicap. If one stone is worth 11 points, then this is a bigger leap than the first one, and so White consistently receives 5.5 points more than he deserves. If one stone is worth 5.5 points, then this system is OK.

So, Bill, your assumptions are:

  • Each successive stone has the same value (which I know you disagree with)
  • This value is 11 points

?


Bill: Each handicap stone (up to 9) has approximately the same value. Playing White (sans komi) is equivalent to having a handicap of 0 stones (i.e., of playing first but passing on the first play). Receiving (proper) komi makes the game even. So (proper) komi is worth approximately half a stone.

About 25 years ago I did some statistics on pro-pro handicap games and concluded that each handicap stone was worth around 13.5 points (territory scoring). (Of course, the estimate was not very precise. I was surprised to find, however, that the relationship was nearly linear. My initial assumption had been that it was not.) Since that implied a proper komi of 6.75, I predicted that the Japanese komi would increase to 6.5 by the turn of the century. Wrong again! ;-) (Nearly: In October 2002, the Nihon Ki-in announced it would start using 6.5 komi).

Somebody else published an article in the AGA journal (Summer, '77, I think) based on over 2,000 Japanese pro games, that indicated a proper komi of around 7.

In the late '70s in New Mexico I ran 4 tournaments a year (around 20 players showed up for each tournament). We divided our ranks into two half ranks. If there was a 1/2 rank difference, the lower ranked player took Black (White winning jigo); if there was a 1 rank difference, he took Black and White gave komi; etc. Komi was 6.5.

After a few years game statistics indicated that White had a slight advantage. However, most games were decided by such large margins that a small change in the komi would not have mattered. Besides, in our small pool of players, the better players (who were more often White) tended to advance more than the weaker players. They were probably more interested in learning the game. :-)


Before the adoption of komi, a different handicap system was in use among top players. See: tagai-sen, sen-ai-sen and josen.


In my experience various Go clubs in Tokyo use a similar point ranking scheme to track players' results and determine the handicap in games. Dave Sigaty


How were handicap games invented?

Frs: A theory: Ancient gobans were smaller than 19x19. One could easily claim territory by starting at tengen, making games rather uninteresting. To prevent this, handicap stones placed at the corners were invented.


See also:



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This is a copy of the living page "Handicap" at Sensei's Library.
(OC) 2003 the Authors, published under the OpenContent License V1.0.