Author: Uri Blass
Date: 10:07:02 07/29/04
Go up one level in this thread
On July 29, 2004 at 11:44:39, Robert Hyatt wrote: >On July 29, 2004 at 10:18:25, Sune Fischer wrote: > >>On July 28, 2004 at 17:48:56, Robert Hyatt wrote: >> >>>On July 28, 2004 at 14:21:26, Sune Fischer wrote: >>> >>>>On July 28, 2004 at 11:02:36, Robert Hyatt wrote: >>>> >>>>>On July 28, 2004 at 03:18:52, Sune Fischer wrote: >>>>> >>>>>>On July 27, 2004 at 18:26:16, Robert Hyatt wrote: >>>>>> >>>>>>>Aha. And exactly how many times do you do the N+1 iteration and get the _same_ >>>>>>>best move? For crafty that is about 85% of the time. So I should cut the >>>>>>>search off one ply early? Or is that 15% critical? >>>>>> >>>>>>I don't understand the question. >>>>> >>>>>you said I wasted time by starting the next search which won't fail low most of >>>>>the time. I said you waste time by doing iteration N+1 that doesn't change the >>>>>best move most of the time. See the fallacy in the argument? I _know_ going to >>>>>depth N+1 won't change the best move most of the time. But it will likely >>>>>change the best move when it is important to do so... >>>> >>>>No. >>>>It's going to depend on how much time you have left. >>>>If you need 5 seconds to fail-low and you have 4 seconds left, you won't see it. >>> >>>No (I can play that game too). :) >>> >>>the game _always_ depends on time. If you run out you have to do something. >>>But again, in 85% of the cases, doing N+1 produces the same best move as N, so >>>it is "wasted" by your definition. I'm interested in that 15% where it changes >>>to something better. Starting the next iteration might produce nothing 80% of >>>the time or more. But if it fails low twice in a game, it may well save me from >>>making a bad blunder... I can't predict whether I will have enough time to get >>>any information back, so I just dive in and search, and if it fails low, I get >>>valuable information. If not, I don't. >> >>Ok it's simple and it works reasonably well. >> >>What I'm suggesting is more advanced, yes it's harder to get working, but >>probably has a higher efficiency if implemented well. > >"more complicated" != "more advanced". I don't believe it is possible to >accurately forecast the time for the next iteration. Which means when is it >appropriate to do that quick nullwindow search? And when you do it and it >returns way quicker than you expected, what do you do with the remaining time? > >There appear to be more problems this way than with what I currently do... > > >> >>>>>I never said "win-win". I said it works better for me after testing. And I >>>>>have done _lots_ of testing with various approaches. That's how I settled on >>>>>the current approach. I'm not much for tea leaves and Tarot cards. >>>> >>>>That interesting, because I was beginning to wonder how you could have such >>>>strong opinions on something you _haven't_ tested. :) >>> >>>I _have_ tested both options many times. >> >>But you have not tested what I'm suggesting. > >I have definitely tested doing a fail-low search. You can find references to >that back in 1978 which was when I finally dumped the idea of "don't start the >next iteration if I don't believe it can be finished..." What is exactly the data that convinced you that this idea is worse than what you did later. I think that the difference in elo is probably less than 20 elo. The main important things are: 1)using more time after you already know about fail low 2)Deciding about target time correctly and it is also a problem that you can solve if you decide to finish at the end of the iteration(you can decide not to start a new iteration if you expect it to be finished after twice the average time that you have for move and you can decide not to start a new iteration if you expect it to be finished after another multiplication of the target time). Note that I have another rule and if the first move of the iteration takes enough time then I decide that it is the last iteration). My logic is the following: There are 2 cases: Case 1:I spend significant time on the rest of the moves(in this case I have no time for new iteration). case 2:I do not spend a lot of time on the rest of the moves. In these cases there is a big probability that the move is forced and other replies are pruned fast thanks to null move pruning so I prefer to use less time for it. Uri
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