Author: Robert Hyatt
Date: 12:44:25 11/11/02
Go up one level in this thread
On November 11, 2002 at 15:04:15, J. Wesley Cleveland wrote: >On November 10, 2002 at 21:29:43, Robert Hyatt wrote: > >>On November 10, 2002 at 21:15:07, Jim Bumgardner wrote: >> >>>Which of these strategies for "think on opponent's time" makes more sense? >>> >>>A) To only search the top-move from the principle variation. If >>>the opponent makes that move, continue searching, otherwise reset and >>>search again. >> >>This is the _only_ way to do it. I've explained this many times, but it >>is probably time to go it again... >> >>Suppose you predict your opponent's move correctly only 50% of the time. >>And it should be pointed out that this is a _low_ estimate from thousands >>of observed games (via log files). This means that 1/2 of the time, you will >>predict correctly and when your opponent moves, you have an instant response >>ready. 1/2 of the time you get to think for free. >> >>Suppose you choose to search the top three moves instead of just the first one. >>When your opponent has moved, you have spent 1/3 of the total time on each move. >>You save 1/3 of the time. And that is worse than saving 1/2. If you only >>search the top 2 moves, you will save 1/2 of the time, _if_ the move played is >>one of those two, but occasionally it won't. >> >>It is really simple to see why searching only the best move is the right >>idea. I could think of a few cases where I might vary this, such as where >>my target time is 3 minutes and my opponent searches for 12 minutes. Do I >>want to search one move for 12 minutes, or do I want to take a chance and >>use 1/2 of that time (say) to search for an alternative best move? Tough to >>say, and although I have tried such ideas many times, I have always come back >>to searching what I consider the best move only. And since 50% is a low >>prediction percentage, searching one move actually is even better than the >>above pessimistic analysis. > >This stratagy is clearly the best until the total alloted time for this move is >used, i.e. you would move instantly if the pondered move is made, as the effect >of pondering is saving time for future moves, and the greatest expected saving >is given by searching the expected moves. After this, at some point the >advantage goes to searching other moves. Maybe. But remember, the effect is just a "deep think". IE I might spot something really good in 6 minutes, but not in 3. If I stop after 3 and go on to another move, I might not find the deep sac... > A clear example of this is asymmetric >time limits, e.g. you have 1 second per move and your opponent has 1 day per >move. Here, you could easily blunder if you have not pondered the move the >opponent actually makes. The point at which to switch depends on the expected >value of searching the current move deeper compared to the expected value of >possible time saved by pondering another move. This is not easy to calculate, >and experiments would need to be done. I'd agree with that. I'm not sure what the time limit would be. But another case is when the opponent crashes. And you are pondering. I've pondered for nearly two hours in a couple of ACM events, and that might be better spent looking at more moves of course. But I am not sure where the 'break-out" point comes...
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