Plus draws

[ildjarn]

Rules for a plus draw (taken from http://www.wkdammen2011.nl/index.php?op ... 34&lang=en) :

14. "Plus Draw"
1. When the result of a game is a draw and when there is a difference of 3 men or more (a king counting for two men, e.g. 2 kings and 1 man against 1 king) then the player with the majority gets a plus draw and his opponent receives a minus draw. This rule holds for the draw by mutual consent (see Annex 1 article 7) and for the regulatory draw (See Annex 1, article 6: three times the same position, the 25 moves rule, the 16 moves rule and the 5 moves rule). The players write a 1+ or a 1- on their notation forms.
2. If a position of a king plus 2 men against a King is reached then, as given in Annex 1 article 6.3, a maximum of 16 moves may be played. If the game is not yet ended the result is a plus draw for the player with the 3 pieces, unless 2 of the 3 pieces are not yet King and their promotion can be prevented by the player with one King.
3. If it is clear for both players that the game will end in a plus draw they may agree upon such a draw even if the difference of three men is not yet reached on the board.
4. If it is clear for both players that the game will end in an equal draw they may agree upon such a draw even if there is a difference of three men or more on the board.

Has anyone created an endgame database generator which includes these plus draws?

[Ed Gilbert]

Has anyone created an endgame database generator which includes these plus draws?

I have not. It is probably not necessary, as I think some simple search heuristics should sufficient for most purposes. Are plus draws going to be used in most tournaments now? If so then I will probably modify the draw heuristics in kingsrow to properly identify them. It presently weights a king as equal to 3 men for the purpose of scoring draws as either 1, 3, or 5, so that would have to change. Equating a king to 2 men in an ending seems small to me. Does anyone know why those weights were chosen?

-- Ed

[BertTuyt]

Also Damage does not have Databases which make a difference between all types of draw scores. To be honest I doubt if there is any program so far with this option. I'm not 100% sure if simple heuristics will be able to differentiate draws. But I might be wrong. In case there is a draw , we don't have included mechanism to detect if the stronger side can gain material which yield a plus score. It is possible but then we need some additional searches. At least in my program the search stops at interior draw nodes, so no additional captures are considered.

Bert

[Ed Gilbert]

Bert, yes the other part of the heuristic solution is to not truncate the search at interior db draw nodes.

-- Ed

[Ed Gilbert]

As an experiment, I modified kingsrow to return a +5 or -5 scores at db draw nodes where there is a plus draw, and I also stopped it from truncating the search at draw nodes. Bert, your instict was right, I was wrong about the usefullness of this kind of solution. It works if the plus draw can be forced within about 30 plies or so, but in too many positions the distance to forcing a plus draw is much further than that. I decided that it is not really very useful, and since it requires giving up the cutoffs that normally occur at db draw nodes, it is not worth this overhead.

-- Ed

[TAILLE]

Hi,

Rules for a plus draw (taken from http://www.wkdammen2011.nl/index.php?op ... 34&lang=en) :

14. "Plus Draw"
1. When the result of a game is a draw and when there is a difference of 3 men or more (a king counting for two men, e.g. 2 kings and 1 man against 1 king) then the player with the majority gets a plus draw and his opponent receives a minus draw. This rule holds for the draw by mutual consent (see Annex 1 article 7) and for the regulatory draw (See Annex 1, article 6: three times the same position, the 25 moves rule, the 16 moves rule and the 5 moves rule). The players write a 1+ or a 1- on their notation forms.
2. If a position of a king plus 2 men against a King is reached then, as given in Annex 1 article 6.3, a maximum of 16 moves may be played. If the game is not yet ended the result is a plus draw for the player with the 3 pieces, unless 2 of the 3 pieces are not yet King and their promotion can be prevented by the player with one King.
3. If it is clear for both players that the game will end in a plus draw they may agree upon such a draw even if the difference of three men is not yet reached on the board.
4. If it is clear for both players that the game will end in an equal draw they may agree upon such a draw even if there is a difference of three men or more on the board.

Has anyone created an endgame database generator which includes these plus draws?

I already generated the 5-pieces draw+ egdb but it was just for experimentation and I did not keep it because I was not satisfied with the format I used. I planned to work on a new format in order to generate up the 7 pieces draw+ egdb but at the same time I decided to work and generate the "standard" 8 pieces egdb.
For the moment I have not (yet) decided to work again on this draw+ egdb but it is somewhere in my brain.