QSearch problem

[tvrzsky]

Hi,
recently I have encountered a problem in my QSearch.
In this position
[d]7R/4K1k1/8/5B2/8/8/8/8 b
where Alfa = 0, Beta = 1 and CurrentEvaluation = -(RookValue + BishopValue), move Kxh8 gets excluded from the search because its SEE value (RookValue) is not great enough to raise the CurrentEvaluation above Alfa. There is just a too big discrepancy between the expected evaluation after the capture (-BishopValue) and reality (Draw because of insufficient material).
So my QSearch returns -(RookValue + BishopValue) instead of Draw from this position what eventually spoiled the whole search via hashtable.
How do you deal with this problem?

[Ferdy]

Hi,
recently I have encountered a problem in my QSearch.
In this position
[d]7R/4K1k1/8/5B2/8/8/8/8 b
where Alfa = 0, Beta = 1 and CurrentEvaluation = -(RookValue + BishopValue), move Kxh8 gets excluded from the search because its SEE value (RookValue) is not great enough to raise the CurrentEvaluation above Alfa. There is just a too big discrepancy between the expected evaluation after the capture (-BishopValue) and reality (Draw because of insufficient material).
So my QSearch returns -(RookValue + BishopValue) instead of Draw from this position what eventually spoiled the whole search via hashtable.
How do you deal with this problem?

In my case, I don't prune moves with SEE >= 0

You might want to add condition related to material, like don't do this in ending stage.

[tvrzsky]

In my case, I don't prune moves with SEE >= 0

It is quite restricting, I am afraid, but I will try it.

You might want to add condition related to material, like don't do this in ending stage.

I like this proposal much more.
Anyway, thanks for ideas!

[mridul]

Just allow all winning captures ... saves a lot of headache - and the node jump is not too high.
i really dont know why people make qsearch unstable with futility !


YMMV ofcourse

Mridul

[Sergei Markoff]

Just include captures which results in having no mating material for the opponent and also use some bound to handle bad trade scores and so on. And also check only See >= captures as was stated above.

[tvrzsky]

Thanks for all your suggestions, my brain looked little bit empty this morning, but you have got me on the right track, I hope .
Filip