Author: scott farrell
Date: 02:00:47 02/08/03
Go up one level in this thread
On February 08, 2003 at 03:25:06, Tony Werten wrote: >On February 08, 2003 at 00:50:22, scott farrell wrote: > >>My idea relies on an underlying use of PVS search (principal variation serach), >>an aspiration window, and IID (internal iterative deepening). >> >>When searching the root position, I search the first move as per normal. >> >>Then I search all remaining root moves at depth-1, basically everything gets a >>reduction. This speeds the already fast PVS search. If any of the PVS searches >>at root fail require a research, I research without the reduced depth. > >I do something like this in XiniX, but since I don't like reductions, I do it a >little different. > >I add a ply to the best move. > I think at the end of the say it is EXACTLY the same. Whether you add a ply to the 1st move, or take a ply off from every other move, its the same. thanks for your comments. I really do beleive this is a powerful idea !!! >My reason for doing this: I don't mind if the engine overlooks something, but if >it looses because the moves were played exactly as it expected then I get upset. This is exactly what prompted me to invest time in this, loosing a game when it followed half way down the PV. And later analysis showed that about 1000 nodes more were needed to see a fail low ..... > >If the first move seems good then 2 things can happen: >A It isn't good at higher depths >B Another move is better. > >B won't make you loose a game ( It just wins slower ) A can kill you. I prefer >to invest more time to avoid A than to get B > There is a big different between not loosing and trying to win !!!! thanks again Scott >Tony > >> >>If at any time I fail low at root without a PV move already, then you panic and >>add time etc, and dont do any depth reductions. >> >>If you fail high, I often just take the move if its near to the time allowed for >>this move, especially if its value is more than our last move on the board. >> >>The idea is based on a few thoughts: >>"why do you try ply 9 when you already have a nice move on ply 8" >>"are you trying to ensure the move is safe?" >>"are you trying to find a better move?" >> >>I think proving your move is safe is far more important. And that is what my >>idea above does. It spends more time on checking that your move is safe, rather >>than looking for a better move. This really helps, when there are 2 candidates >>moves, and they are very close in score, and your engine spends lots of time >>flip-flopping between them as best. My idea disregards the second, until it can >>be shown it is much better. >> >>When you have finished searching say ply8, you have really only searched ply8 >>for the best move, and ply7 for everything else, unless you found a problem with >>the best move and panicked. >> >>In positions where you have 1 clear good move, things really get an amazing >>boost. In positions with lots of traps, it takes just as long as normal (ie. no >>slower), but finds the traps more quickly, and during a game gives you the fail >>low more quickly in order to allocate more time. >> >>I implemented this in chompster, and it seems to have had no drawbacks. It has >>been averaging around 2450 on ICC in recent weeks, pretty good for Java !! >> >>This will be especially useful for 'newer' engines that arent real good on time >>management, and only search full plies at the moment - this sort of allows you >>to search partial plies when it is safe to do do. >> >>Let me know what you think, and if you might give it a try in your engine. >> >>Scott
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.