Cardoso wrote:Hi,
I've been thinking about this. Is there any real benefit to extend a line at ply 2 or 3 or 4... if we ave a remaining depth of say 15 plies?
Shouldn't we only do extensions if we have remaining depth > 4 plies?
Because that is where we are running out of remaining depth and horizon problems occur.
What do you think about this?
Alvaro
I've tried a ton of different ideas over the past 6 months or so. What I found, in general, was that anything that reduced the number of extensions seemed to help, with the exception of the check extension. Now that I have all other extensions removed, I am going to go back and try some runs to see if limiting the check extension, either closer to the root or closer to the tips makes any significant difference...
I wonder if you tried pv extensions.
It means extending the line of the pv of the previous iteration.
based on my memory toga does it.
Uri
Yes. In my testing that was worse. I don't recall exactly and could do the test again, but it was worse than any of the other extensions I tried... The idea doesn't make any particular sense to me either.
I am surprised that the idea does not make sense to you
The point is that it is logical to extend logical moves and the pv has logical moves.
I do not see why reducing late move make sense when extending first moves in some cases does not make sense(and the pv moves are certainly the first moves to search).
Maybe this idea needs limitation like extending the pv only if the pv moves are singular and it is possible that the first pv move is wrong but it leads to some forced line that only extending it can help the computer to see the problem.
bob wrote:I've tried a ton of different ideas over the past 6 months or so. What I found, in general, was that anything that reduced the number of extensions seemed to help, with the exception of the check extension. Now that I have all other extensions removed, I am going to go back and try some runs to see if limiting the check extension, either closer to the root or closer to the tips makes any significant difference...
Have you tried extending checks by just half a ply, like I do in Glaurung? When I watch my engine play, it looks faster and stronger with check extensions limited to half a ply, but as usual, I can't back it up with statistics. I could be wrong.
Tord
I extend half a ply, but the first iteration is really iteration 1.5, so that the first half ply extension triggers a true depth increase.
The other issue is how you "pre-load" the search depth when you start. I tested with 0, 1/4, 1/2 and 3/4, which means the first iteration is depth+N where N is one of those 4 values. not surprisingly, 0 was best (it doesn't affect the check extensions and delays the extensions caused by the others by at least a ply or two.
Hmm, I may have to revisit this. I see to do better when I start the search with a half ply extension.
