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BUG: draw assigned while still having mating potential

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javabean

Pawn

Posts: 8

Joined: Thu May 19, 2011 1:33 pm

Post Fri Jun 24, 2011 11:06 pm

BUG: draw assigned while still having mating potential

When the CC system detects two lone kings on a board, it automatically assigns a draw. This is correct, obviously.

When the CC system detects K+N vs K+B however, it also automatically assigns a draw. No mating potential is given as the reason. However, this is *not* correct. It is possible to construct a mate rather easily, e.g. Ka6, Nb6 for white and Ka8, Bb8 for black. It doesn't matter if one side has to (willingly) cooperate to make the mate possible. Also endings like K+2N vs K, which are theoretically drawn, still have mating potential. It is possible to lose these positions.

Having seen this when watching a game I assume that other combinations exist where the CC system will incorrectly assign a draw.
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xabichess

User avatar

Rook

Posts: 322

Joined: Fri Feb 04, 2011 1:50 am

Post Fri Jun 24, 2011 11:47 pm

Re: BUG: draw assigned while still having mating potential

Javabean: for mating with just a knight against a bishop and a king, is something really unlikely to happen, unless you are trying to let it happen. It is the same as 2knights vs king unless you want to get mated you won't get mated. I do not think those are incorrect draws. If you believe you can mate me in less than 200 moves with two knights against a king where there is no force mate in the first move I believe you cannot mate me.
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javabean

Pawn

Posts: 8

Joined: Thu May 19, 2011 1:33 pm

Post Sat Jun 25, 2011 7:49 am

Re: BUG: draw assigned while still having mating potential

I still not think it's up to the system to declare the draw instantly, especially not in blitz.
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xabichess

User avatar

Rook

Posts: 322

Joined: Fri Feb 04, 2011 1:50 am

Post Sat Jun 25, 2011 12:21 pm

Re: BUG: draw assigned while still having mating potential

javabean: unless it is mate in 1 when you lose your last pawn it is imposible to mate no matter if it is blitz, bullet or blind chess.
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bryan

Site Admin

Posts: 125

Joined: Thu Nov 11, 2010 3:03 pm

Location: Cape Town

Post Sat Jun 25, 2011 12:39 pm

Re: BUG: draw assigned while still having mating potential

javabean wrote:When the CC system detects two lone kings on a board, it automatically assigns a draw. This is correct, obviously.

When the CC system detects K+N vs K+B however, it also automatically assigns a draw. No mating potential is given as the reason. However, this is *not* correct. It is possible to construct a mate rather easily, e.g. Ka6, Nb6 for white and Ka8, Bb8 for black. It doesn't matter if one side has to (willingly) cooperate to make the mate possible. Also endings like K+2N vs K, which are theoretically drawn, still have mating potential. It is possible to lose these positions.

Having seen this when watching a game I assume that other combinations exist where the CC system will incorrectly assign a draw.

This is standard practice for most online servers. We need to code for the situations that are the most probable, not extreme outliers, as you mention. Basically probability trumps theory in this case. If, however, you do find yourself in such a situation where mate is FORCED, you can write to [email protected] and we can investigate it.

Overall we feel it does not make the site better (in terms of fairness or sportsmanship) to let players with K+N, K+B play on just to eventually win on time. Many users will just take advantage of this - playing MANY moves and HIGHLY annoying their opponents just to get the win on time.
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javabean

Pawn

Posts: 8

Joined: Thu May 19, 2011 1:33 pm

Post Sat Jun 25, 2011 3:02 pm

Re: BUG: draw assigned while still having mating potential

bryan wrote:Overall we feel it does not make the site better (in terms of fairness or sportsmanship) to let players with K+N, K+B play on just to eventually win on time. Many users will just take advantage of this - playing MANY moves and HIGHLY annoying their opponents just to get the win on time.


Ok fair enough. I hate it when people do that myself!
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thegreatsolar

Pawn

Posts: 4

Joined: Tue Apr 19, 2011 8:32 am

Post Sun Jun 26, 2011 9:34 am

Re: BUG: draw assigned while still having mating potential

Well, I actually see both sides of the argument, and find it hard to agree that the aforementioned scenario should be a draw based on the logic that it's "bad sportsmanship" to win on time. The rules allow plenty of ridiculous scenarios, as you can be a queen down and still easily win on time in many situations. Disappointing losses on time are a huge part of this game, and taking a win away from someone because it's an improbable win is not a fair motion.

I'll give you a realistic scenario of why it's not fair:

The lazy player has taken too much time on each move, and has just ten seconds left on his clock. His skilled opponent has two minutes on the clock, and has a sufficient lead in material. The player with ten seconds left decides to aim for a K+2N vs K by sacrificing his bishop. How does he deserve to earn a draw for this play? Assuming it's still possible to mate, and winning on time is acceptable, isn't it easier to win on time when you can deliver checks, while your opponent has to worry about avoiding mates, while often times being unable to premove?
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xabichess

User avatar

Rook

Posts: 322

Joined: Fri Feb 04, 2011 1:50 am

Post Wed Jun 29, 2011 9:32 pm

Re: BUG: draw assigned while still having mating potential

Dear Thegreatsolar and javabean,

I can't believe that you can mate with just k+2N or K+B or K+N against a sole king, thus why bother moving hopelessly if there is no way to mate, unless it is mate in 1 which I don't know if it can even be made.

I don't think it is lame if you have K+ 2N against K+pawn to just go for the draw since you won't mate with 2Ns+K against a K and you won't let the pawn get to queen and try to mate you... I don't see the posibilities you see to mate. I mean just tell me a real game were you mated with K+N or K+2N against K alone or K+N or K+2N or K+B.
Getting to a game that you have the position of mate in 1 or forced mate after getting to these material is as likely as getting hit by an asteroid or being engulged by a black hole.

I think it is a waist of time and effort having the a program looking at each game just for the unlikely case you may have a forced mate after getting to these kind of positions, since if you miss it, you can't mate.

Regards Xabier.

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