Two knights vs two same-colored bishops

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Nordlandia
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Two knights vs two same-colored bishops

Post by Nordlandia » Fri Sep 06, 2019 8:00 pm

Is it possible to quantify the advantage of two knights over two bishops of same color.

The power of the two bishops is often because one can reach the squares the other cannot. With a mostly empty board, one of the two bishops can often control any square on the chessboard in one move. But if the two bishops are the same color, they lose this property. The two same-colored bishops can't do much that one bishop couldn't do, and really can't do much that a bishop plus another minor piece couldn't do.

Two knights is less redundant than two bishops of same color. But how much does the this advantage constitute - half a pawn or more?

Let use this position. How big is white's edge here?



I know about this engine game


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hgm
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Re: Two knights vs two same-colored bishops

Post by hgm » Fri Sep 06, 2019 8:08 pm

With all material present two same-colored Bishops (the 'anti-pair') are equally strong as two Kights or Knight + Bishop, and about half a Pawn weaker than two Bishops on different shades. To measure it for this end-game position you woul have to do a few hundred games of engine self-play.

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Re: Two knights vs two same-colored bishops

Post by Nordlandia » Sat Sep 07, 2019 6:57 am

hgm wrote:
Fri Sep 06, 2019 8:08 pm
With all material present two same-colored Bishops (the 'anti-pair') are equally strong as two Kights or Knight + Bishop, and about half a Pawn weaker than two Bishops on different shades. To measure it for this end-game position you woul have to do a few hundred games of engine self-play.
What time control do you recommend. And what contemt value should i use, default?

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Re: Two knights vs two same-colored bishops

Post by hgm » Sat Sep 07, 2019 8:08 am

It shouldn't depend on TC which side is better, so you can use a fast TC to quickly play many games. I would expect contempt to be detrimental against an equally strong opponent (as in self-play). Furthermore, if both engines would play with the same non-zero contempt, it would not really be self-play, as they would differ in opinion about the (white POV) score for repetitions. To be consistent they would need opposite contempt. And under those conditions the value of the contempt would not matter that much, as there would always be one side that thinks a draw is a poor result.

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Nordlandia
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Re: Two knights vs two same-colored bishops

Post by Nordlandia » Sat Sep 07, 2019 9:39 am

So in case using stockfish developmental version of Mon Aug 26. One side use +24 while the other use -24. TC of 15s+ 0.85s may be suffient i suppose.

What time control do you usually use when generating selfplay games in large numbers?

Raphexon
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Re: Two knights vs two same-colored bishops

Post by Raphexon » Sat Sep 07, 2019 10:10 am

I just read this article about bishop vs knight.

http://blog.abrok.eu/bishop-vs-knight/

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Re: Two knights vs two same-colored bishops

Post by Uri Blass » Sat Sep 07, 2019 10:51 am

hgm wrote:
Sat Sep 07, 2019 8:08 am
It shouldn't depend on TC which side is better, so you can use a fast TC to quickly play many games. I would expect contempt to be detrimental against an equally strong opponent (as in self-play). Furthermore, if both engines would play with the same non-zero contempt, it would not really be self-play, as they would differ in opinion about the (white POV) score for repetitions. To be consistent they would need opposite contempt. And under those conditions the value of the contempt would not matter that much, as there would always be one side that thinks a draw is a poor result.
How do you know that it should not depend on TC which side is better?

I think that the only way to know is by playing games at different time control and see that you get similiar results.
Without games between engines you cannot know.

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Re: Two knights vs two same-colored bishops

Post by Nordlandia » Sat Sep 07, 2019 11:45 am

Raphexon wrote:
Sat Sep 07, 2019 10:10 am
I just read this article about bishop vs knight.

http://blog.abrok.eu/bishop-vs-knight/
Thanks for the link. He didn't should examine Queen + Knight tandem against Queen + Bishop.

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