Author: Peter Berger
Date: 16:51:33 03/27/04
For about a month I have waited for someone to bring this up now. Occasionally I thought I should post about it, but then I thought someone else (a much more knowledgeable guy at best) would do it anyway sooner or later. I decided to just do it now and not bother to do it very well at all. This is about Ruffian 2.1.0 I bought at Lokasoft's ( it probably applies to other Ruffian 2 versions too). Now how does Ruffian 2 ponder? Usually programs assume the second move of the PV as being played, and then think as if it were their own move in the meantime. If the expected move gets played indeed, some (loads of at times ) time has been saved - else the time is lost (despite some potentially useful entries in the hashtable). Another approach ( inferior) is to just think as if you were the opponent during ponder and rely on savings from the hashtable you achieved -you get some useful entries in the hashtable anyway, but this can't be an optimal strategy IMHO. Now Ruffian _does_ think as if it were the opponent during pondering, too, but in case the expected move is played it does the same as the usual strategy does during pondering but one ply further. The second move in the PV is the move to be played in case time has already run out, else some time has been saved of course. Again, if another move has been played, the time is lost. There have been some speculations about a potential Ruffian ponder bug recently, but this one that looks _very much_ like a design decision hasn't been discussed yet afaik. Potential advantages: if the opponent takes an extra long think to find a new move in a tough position and succeeds to do so (fail-low situation) , you are doing the same. If there is something better indeed Ruffian will probably find it too, and then have a good move in response already prepared. The disadvantages are also clear: you just lose one ply of depth at least in case you would have guessed the right ponder move anyway. From a percentage point of view this looks wrong: you will guess the right move clearly more than 50% of the time in comp-comp games. The question is if the importance of the exception cases makes up for it IMHO. I have discussed this one very briefly with Dieter Buerssner whose first reaction was: this way of pondering is even worse than no pondering at all. I hope he doesn't feel offended to see such a spontaneous first reaction posted in case he is wrong, but it might be interesting to know nevertheless. All this is based on my observation of very few Ruffian games and it is possible that my interpretation of the program output is very wrong. But what I have seen clearly goes well with it. If all this is nonsense, it will be embarrassing ;) - but why not make a fool of oneself occasionally ?! Btw, if this Ruffian ponder approach is a great idea, you need a completely symetrical evaluation of course , dunno if this is a decided issue. Peter PS: I really hope I managed to post in an understandable way languagewise - as it's 2 AM here ;)
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