Author: Ed Schröder
Date: 20:50:06 05/27/04
Go up one level in this thread
On May 27, 2004 at 18:41:53, Volker Böhm wrote:
>On May 27, 2004 at 11:59:43, Ed Schröder wrote:
>
>>On May 26, 2004 at 13:34:23, Robert Hyatt wrote:
>>
>>>On May 26, 2004 at 12:30:33, Tord Romstad wrote:
>>>
>>>>On May 26, 2004 at 12:13:03, Robert Hyatt wrote:
>>>>
>>>>>On May 26, 2004 at 10:53:16, Stefano Gemma wrote:
>>>>>
>>>>>>I've used an recursive-iterative deepening. I try to explain in my poor english.
>>>>>>At any N plyes i've applyed iterative deepening as for the root. Suppose to
>>>>>>start with 2 plies. The next iterations you should search 4 then 6 then 8 plies
>>>>>>etc, form the root. But, when you're searching 8 plies depth, and you are at a
>>>>>>position located at ply 2, why don't use iterative deepening starting from ply
>>>>>>2, instead to do a full search of the remaining 6 plies? So i've tried to
>>>>>>consider positions at ply 2 (and 4 and 6...) as they were at the root, and start
>>>>>>a search to ply 4, then 6, then 8. Sometimes works better, sometimes worse...
>>>>>>
>>>>>>I have tried different schemas, in Raffaela. The best seems the schema 2-4. You
>>>>>>increment the iterative deepening by 2 plies (one chess move by colour) and, for
>>>>>>any ply, you make an iterative deepening with increment 4. In some position, 2-2
>>>>>>was better.
>>>>>>
>>>>>>I've abandoned this idea, for now, because i'm working on a new engine and i've
>>>>>>little time for my hobby, but i think that could be interesting.
>>>>>>
>>>>>>Ciao!!!
>>>>>>
>>>>>>Stefano Gemma
>>>>>
>>>>>
>>>>>That sounds like an interesting idea that is worth testing. IE at _any_ ply
>>>>>where you want to do a depth=N search, you iterate and do a depth=1, 2, ..., N
>>>>>to work your way up to that point. With luck the depth 1 to n-1 searches will
>>>>>be cheap with hash information, if there is none, move ordering will probably be
>>>>>broken anyway and this might improve things.
>>>>
>>>>This is exactly what I always thought was called "internal iterative
>>>>deepening", but I have recently learned that others use this term to refer
>>>>to something different.
>>>>
>>>>I use something similar to Stefano's technique (if I understood it correctly)
>>>>at all internal nodes where the remaining depth is high (currently 5 plies or
>>>>more) and I expect a fail high.
>>>>
>>>>Tord
>>
>>>I have used "IID" for years, but in a very restricted way, namely to handle the
>>>case along the PV where I have no hash move. I've never tried it _everywhere_
>>>before, so have no data. But I intend to try to see if it is something that
>>>could work, or if it is a waste...
>>
>>Try to use IID in another way. Actually I found 2 ways that perform better than
>>the original IID idea.
>>
>>Preamble: RD = remaining depth
>> R = reduction depth
>>
>>1) if (RD >= 3) search all moves with R=(RD-2)+(RD/2) then search all moves
>>again with the full depth. The principle applies only once in an unsorted tree,
>>thus is not recursive.
>>
>>2) if (RD >= 3) search a move with R=(RD-2)+(RD/2) and when finished research
>>that move again with the full depth. The principle applies only once in an
>>unsorted tree, thus is not recursive.
>>
>>I have tried RD>=2 too but found that normal move ordering is superior.
>>
>>Ed
>
>Sorry if my question is silly.
>For example with RD == 10 R gets (10-2) + (10 / 2) == 8 + 5 == 13. What to do
>with "13"? It cannot be the new remaining depth and it cannot be R - 13 as this
>is negative.
>Is there a bug in the formular or do I miss something?
I have not been careful enough. Actually I do: R=table[RD];
static char table[]= {
0, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
9, 9,10,10,11,11,12,12,13,13,14,14, etc. }
So an RD of 10 becomes a reduction of 6.
Ed
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