Author: Stefano Gemma
Date: 23:27:40 05/27/04
Go up one level in this thread
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... In my engine, it seems to works well in some situations and bad in others. I don't know what could happen to a program with hash-tables, because i don't have HT. The RID idea should theoretically works, but maybe it was better to use a dynamic schema, depending on the "entropia" of the ordering. If i search from ply N to ply N+2 and get an ordered list of moves, then i search to ply N+4 and get a very different ordering... well, i should try ply N+6. If the ordering remains the same, then maybe i haven't to order deeper and i can start the full search to ply MAX. This looks like quiescence, but related to recursive iterative deepening pre-ordering search. (PS: i search N+2...4...6 because i don't use quiescence) Ciao!!! Stefano Gemma
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