Author: Robert Hyatt
Date: 06:36:42 09/05/99
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On September 05, 1999 at 04:09:58, Pauli Misikangas wrote: >On September 04, 1999 at 22:15:16, Robert Hyatt wrote: > >>The measurement I do inside crafty is to count the number of positions where I >>get a fail-high, and then count the number of positions where I get a fail high >>on the _first_ move I search. I am generally seeing this average about 94%, >>which means 94% of the times when I fail high, I fail high on the first move, >>which is pretty good. > >Have you tested what this "first-fails-high" percentage is when searching to >different depths? In other words, instead of using only one counter for >fail-highs, use one for each depth. So, if you get a fail-high in a node that >was searched to depth d, increase counter fail_high_counter[d] and if the move >was the first one, increase also first_failed_high[d]. What kind of >first-fails-high percentages (100*first_failed_high[d]/fail_high_counter[d]) do >you get for each d? > >In my understanding, finding a fail-high move quickly is much more important in >nodes near the root than in leaf nodes. If you don't count fail-highs separately >for each depth, fail highs in leaf nodes will dominate and hide possible >weaknesses in move ordering near the root. Do you agree? > >If 94% first-fails-high percentage is "pretty good" for a chess program, what >would you expect the percentage to be for a shogi program that has a good move >ordering? In shogi, you have average 80 possible moves per turn while in chess >you have "only" 35. > >All the best, > >Pauli Misikangas The only thing I have tested is fail-highs on a per-ply basis... and not surprisingly plies near the root get nearly 100% fail highs on the first move, plies near the end of the search are worse... But even they are not terribly bad... because to maintain 94% requires that 94% of all fail high positions fail high on the first move... and most of the fail high positions are in the last 1/2 of the tree...
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