Re: Fruit and History Reductions
Posted: Sat Jul 21, 2007 7:01 pm
I don't keep all data. There's simply too much. But the "pattern" was that reductions work, but using history information is not helpful. And simply disabling it completely but still doing everything else in the reduction algorithm normall produces results just as good and less random.Uri Blass wrote:It may be interesting to see the results that you say that there is no pattern.bob wrote:For example, I took fruit and varied the history threshold from 0 to 100% of max. 0 effectively turns it off and that was worse. But once I turned it on, there was no "pattern" that said 10 is better than 0, 20 is better than 10, 30 is better than 20, ..., 60 is worse than 50, 70 is worse than 60, etc. The results showed that for Fruit (and for Crafty) varying this threshold (and fruit and crafty did not quite compute it the same way either) had no quantifiable influence on playing strength. I played 10K games per value, to get rid of almost all the randomess of the results.Uri Blass wrote:I disagree that history counters are nothing more than a good source of random numbers.bob wrote:Source will be available soon. But simply we look at each individual move to decide whether to reduce it or not. At today's depths, the history counters are essentially nothing more than a good source of random numbers...Cardoso wrote:Could you please tell me about those methods?
It has been some time I don't read the latest crafty's source.
Are those implemented in the latest version of crafty?
I did some experimentation with Crafty/Glaurung/Fruit a while back, and discovered that varying the history threshold for fruit has no significant impact on its overall game results, _IF_ one plays enough games to eliminate the inherent randomness in computer chess games.
Maybe experiment suggest that they are not productive for you but if it is the case it suggests that maybe you should count in a different way and you may decide to memset the history counters every time that the remaining depth is high enough so history counters will be based only on results of small depth search.
"varying the history threshold for fruit has no significant impact on its overall game results"
I do not understand what is the experiment that you did.
Note that based on my knowledge history threshold in fruit means conditions for late move reductions when history threshold of 0 mean no late move reduction.
I believe that late move reduction help fruit so changing the history threshold clearly change the playing strength of fruit.
I then removed it and still produce the same results as when I had 'em in. And when I say "I removed it" I mean I simply removed the history counter restriction on what gets reduced...
It is possible that the optimal value is 55 and the difference betwen 40 and 50 and 60 and 70 is simply too small but even in that case I will say that there is a pattern if all values of 40-70 are clearly better than 10.
Note also that results may be dependent on the time control.