Author: Koundinya Veluri
Date: 00:42:47 09/28/01
Go up one level in this thread
On September 28, 2001 at 00:58:15, Dann Corbit wrote: >On September 27, 2001 at 23:44:19, Robert Hyatt wrote: > >>On September 27, 2001 at 19:05:43, Dann Corbit wrote: >> >>>On September 27, 2001 at 17:48:32, Peter Fendrich wrote: >>>[snip] >>>>Yes, I buy all that. My intention was to oppose to the "it's impossible" >>>>statement. You are talking about some general case. There is no reason why each >>>>move has to be 20% because the first one is. That's why I'm talking about >>>>isolating cases where the other move might be better. Another question is what >>>>happens if the ponder move has only 10% or 5% probability. >>>>I have no proofs that these cases are possible to identify but I'm still open >>>>for it, until I know better... >>> >>>Also, it does not have to be either/or. >>> >>>We could ponder the root for 1/2 of the extrapolated opponent time slice, and at >>>that point, change to the pm and ponder that. >>> >>>It seems to me that there are many possibilities. >>> >>>Something that is puzzling me... >>>If one move is really much better than the others, then we would think that it >>>would fail high, re-search, and gobble most of the time anyway. If that does >>>not happen, then some of the alternatives must be pretty good. >>> >>>So, why does pondering root yield only a 2% gain, and pondering the pm give an >>>enormous one? >>> >>>It still does not make sense to me. >>> >>>I guess I'm just having a hard time understanding why it is so much better to >>>ponder the pm instead of the root. >> >>If by "root" you mean the position _before_ any opponent move, then the reason >>is obvious... you will spread your time over N moves, which means that when >>the opponent moves, you will have looked at the _right_ move only 1/N of the >>time. You still have a long time to search to meet the target time for this >>search. > >By the root, I mean "the root move for the opponent -- after I have made my move >but before the opponent returns the response. In other words, the opponent's >current position. > >If the search is so even that time is distributed over N moves, then the chance >of picking the right one is only 1/N anyway. > >If two or three moves are far better than the others, then most of the time will >have been spent searching them. Let's say white was searching and found several moves to be about equal so it decided to ponder the root instead of a particular move. I think in most of these positions, Black will also have a hard time to single out just one or two moves. Since white had a hard time picking one or two outstanding moves out of its list, most probably the position is stable and black will find that most of its moves are also exchangable. Therefore, pondering the root won't help much (in my opinion) because most probably a lot of the reply moves will also be near equal and a search from the root can't single out a couple of moves that it will spend most its time on. So the time will be more or less distributed evenly across the N moves. Koundinya > >If one move is dominatingly better, then most of the time will have been spent >searching that time anyway (because of fail-highs). > >Now, that's on the one hand. On the other hand, picking the right move to >ponder probably has a big kick of extra value. That's because I often see test >positions that computers cannot solve in a long search, but once they get the >key move, they solve it immediately.
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