Additional info:
Also, I changed the "late move reduction" algorithm to make it more
"correct." Here is exactly what I do:
1. At any node - I first must try 3 moves before considering
anything else.
2. Additionally, I try captures even if I've already tried 3 moves.
3. Otherwise, I reduce the depth 2 ply.
4. If 2 ply search returns a score > alpha, I re-search to full depth.
5. If a reduction produces a 0 ply search or less, I simply call
the evaluation function.
I reduce 2 ply to deal with the parity problem. However there is still
a parity issue in some cases when the reduction parity doesn't match the
re-search parity - so this may not be my final formula. I generally
test everything I try so I usually don't get answers for at least a day
or two.
- Don
Don Dailey wrote:
>
>> DF: how many ply is your usual search? I'm getting 3 to 6 ply in the main
>> search, but the quiescence search often adds another 3 to 8 ply. The Q
>> search has almost all the nodes.
>>
>> Right now I use weak patterns to "veto" moves from the tree. If a
>> move is below a given rating I don't even try it if I am on the last 4
>> ply of the search
>>
>>
> I want to clarify this. FooBar is currently doing fixed 3 ply
> search and not looking at the time clock on CGOS time-controls.
> BUT, this is for 9x9 games. It occurred to me that you might be
> talking about 19x19 games which I haven't tested.
>
> I don't currently use any form of quies because my evaluation function
> consists of N play-outs, where N might be around 100 - 200 play-outs
> or so. It might still be useful to have a layer that deal with
> difficult to resolve situations but with play-outs you don't need
> quiescence the same way you would with a static evaluation function
> that is relatively naive about tactics such as a chess style
> evaluation function.
>
> Sometimes FooBar has 2 or more minutes left at the end of a totally
> played out game doing fixed 3 ply searches. A lot of the time is
> taken up by just 3 or 4 early moves and most of the 3 ply searches
> return very quickly - so FooBar would be doing a fair number of 4 ply
> searches in the middle game if I had time-control. I'll fix this
> soon, hopefully it will give a nice improvement - I hope to get about
> 50 ELO or more for this. To get even time management I may have to
> sacrifice 2 or 3 of the 3 ply searches to get a more 4 ply searches.
>
> I can do 5 ply searches in about 85 seconds per move on average - it
> varied from about 40 seconds to 200. I did this estimate with 10
> middlegame positions. The branching factor seems to be about 3.5 per
> iteration. I'm going to test this to 7 ply later.
>
> *DEPTH TIME BF
> ----- ----- -----
> 2 2.2 -
> 3 7.9 3.6
> 4 24.3 3.1
> 5 84.7 3.5
>
> *
>
>
>
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