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Threat detection
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Rasmus Althoff



Joined: 30 Aug 2016
Posts: 478

PostPost subject: Re: Threat detection    Posted: Wed Sep 13, 2017 10:54 pm Reply to topic Reply with quote

hgm wrote:
The fact that the null-move refutation was a non-capture implies that all captures failed low. So it seems that you would only have to try new captures here


Mh yeah, but that would require quite some rewrite, especially since there is no kind of tracking of moving piece vs. null move. I'm not sure whether this tracking would break even. And SEE isn't there anyway right now.

Quote:
And a mistake in move ordering is never fatal.


Yes, it's just about itching out a bit more performance.

Quote:
(You take the first that happens to work.)


Not in the pre-sorting, which is pretty important because it influences the move ordering also in the "real" search at depth level root-1. Since also the root null move refutation is scanned with full window, the null move refutation is actually the best move with depth 2 plies.

Quote:
So perhaps it would be better to bet on the normal killer


That is also in place, though I'm not yet completely clear what has more influence. It's a bit hacky.. Smile For the moment, it seems to me that the null move refutation was overvalued, ranking it always to the top after hash and PV move.

Quote:
Well, if it is a capture in the null-move search, and not now, it means you are moving to a square attacked by the piece that was there after the null move (which can move back to capture you). This does not soud very advisable.


Good point. Just tried to only ramp up the null move refutation if it has been a quiet move both in the null move search and also in the actual occuring move list, but that doesn't seem to have noticeable influence on the node count.

Quote:
Basically you want to search everything that is within ~50cP from the best move, to get a good sorting of the early part of the move list.


OK, so the basic idea to limit the window isn't that bad. The issue is that I don't know the "best" move when starting the sorting, but I can use mini-pre-pre-search of 1 ply plus QS to get an idea what the current eval should be.

I'll have to check out how that interacts with the optional CPU throttling, which only kicks in after the pre-sorting; the pre-sorting in itself already gives a semi-decent move along with a mini-PV in that mode. But I guess there won't be that many winning moves in the same position, usually it's only one anyway.

Thanks. Smile
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Display posts from previous:   
Subject Author Date/Time
Threat detection H.G.Muller Sat Sep 09, 2017 2:55 pm
      Re: Threat detection Evert Glebbeek Sat Sep 09, 2017 5:06 pm
            Re: Threat detection H.G.Muller Sat Sep 09, 2017 6:04 pm
      Re: Threat detection H.G.Muller Sun Sep 10, 2017 10:19 am
      Re: Threat detection Rasmus Althoff Sun Sep 10, 2017 12:53 pm
            Re: Threat detection H.G.Muller Sun Sep 10, 2017 8:00 pm
                  Re: Threat detection Rasmus Althoff Sun Sep 10, 2017 9:55 pm
                        Re: Threat detection H.G.Muller Sun Sep 10, 2017 10:25 pm
                  Re: Threat detection Rasmus Althoff Wed Sep 13, 2017 8:21 pm
                        Re: Threat detection H.G.Muller Wed Sep 13, 2017 9:10 pm
                              Re: Threat detection Rasmus Althoff Wed Sep 13, 2017 10:54 pm
      Re: Threat detection Dennis Sceviour Mon Sep 11, 2017 8:37 pm
      Re: Threat detection Thomas Kolarik Mon Sep 11, 2017 9:39 pm
            Re: Threat detection H.G.Muller Tue Sep 12, 2017 9:29 am
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