TT in Qsearch

Discussion of chess software programming and technical issues.

Moderators: hgm, Harvey Williamson, bob

Forum rules
This textbox is used to restore diagrams posted with the [d] tag before the upgrade.
Post Reply
lauriet
Posts: 161
Joined: Sun Nov 03, 2013 8:32 am
Contact:

TT in Qsearch

Post by lauriet » Tue Dec 05, 2017 1:27 am

Hi all,
Just a quick question: Should I try for a TT score in the Qsearch first, before generating the capture moves ?

Laurie

jdart
Posts: 3510
Joined: Fri Mar 10, 2006 4:23 am
Location: http://www.arasanchess.org

Re: TT in Qsearch

Post by jdart » Tue Dec 05, 2017 1:50 am

There is a tradeoff. Since there are a huge number of qsearch nodes, using the hash table in the qsearch can be expensive and can cause a lot of memory contention as multiple threads try to access the shared hash table. On the other hand, every time you get a hit you save possibly all of the searching from that node or at least the move generation (because you either get a cutoff, or will get a hash move to try first and it may cause cutoff).

--Jon

lauriet
Posts: 161
Joined: Sun Nov 03, 2013 8:32 am
Contact:

Re: TT in Qsearch

Post by lauriet » Tue Dec 05, 2017 6:13 am

I should have mentioned I'm only using a single thread.

phhnguyen
Posts: 278
Joined: Wed Apr 21, 2010 2:58 am
Location: Australia
Full name: Nguyen Hong Pham
Contact:

Re: TT in Qsearch

Post by phhnguyen » Tue Dec 05, 2017 6:55 am

Yes, you should try yourself since it may work for someones but not others.

For me, it did not work with my engine of a single thread when I tried long time ago. I tried both the normal hash table and a special one I had designed for qs only. The success rate was too low, making my engine be (bit) slower.

tomitank
Posts: 170
Joined: Sat Mar 04, 2017 11:24 am
Location: Hungary

Re: TT in Qsearch

Post by tomitank » Tue Dec 05, 2017 12:41 pm

lauriet wrote:Hi all,
Just a quick question: Should I try for a TT score in the Qsearch first, before generating the capture moves ?

Laurie
I added to my engine, but only at depth == 0 (first ply in Qsearch).
I just read the eval value, I do not store anything here, because that did not work better for me.
This give me ~40 elo!

Here is my full (JavaScript) code:
https://github.com/tomitank/tomitankChess
or:
http://talkchess.com/forum/viewtopic.php?t=65899

Post Reply