The Knightmate Challenge 2010

[Richard Allbert]

Ok, thanks.

But there was no rule broken here...?

This is more important for me at the moment... no crashes, or 50 move rule problems.

[Richard Allbert]

Hmm.

I've played through the game with Jabba here... it sees the promotion, but keeps pushing the promotion down the pv... as the game progresses, the promotion is always six moves or so into the pv, with hash tables on and off.

Any ideas what this might be?

The evaluation of the position is the same here regardless of the bishop position - could this be a factor?

Richard

[hgm]

Pure minimax does not care if you promote on the first move, or on the 6th. As long as you have the Queen in the end-leaf, you get the score for it. I guess here there is some funny kind of horizon effect in operation: If you promote early, the opponent's Royal Knight has more time to flee towards the center, which presumably increases black's score. If you promote late, he will be close to the corner in the end-leaf, as he must stay in the corner to defend against promotion.

So of all lines of equal depth that do not have the checkmate within the horizon, the ones where you postponed driving the opponent's Royal Knight out of the corner, and promote, until the last possible moment probably gets a better score. The (transient) price of promotion is that you let the Royal Knight escape to the center, and it tries to push that price over the horizon.

In my engines behavior like hat is discouraged through the delayed-loss bonus. I am not sure how others solve it.

[Richard Allbert]

Yes, I see what you mean. I think this is the case, because after reading your post, I spent most of last night digging up hash table threads on this forum, and playing through test positions to check that all was ok with the hash!!



Can I ask how you apply this score? A bonus for seeing it earlier (depth based?)


Regards

Richard

PS It would be nice if you ran another tournament

[hgm]

I will open a thread for this in the programming section, as I think this is of more general interest than just Knightmate.