Author: James T. Walker
Date: 16:37:23 03/28/99
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On March 28, 1999 at 14:04:00, blass uri wrote: > >On March 28, 1999 at 13:38:26, Sylvain Renard wrote: > >> >>>Fritz is using the tablebases only at the root so I do not understand what is >>>the problem to add engine thinking to the knowledge of the database. >>>It is enough to add some if then commands. >> I was not reallty talking about the difficulty of programming >>this , but about the "contortions" you have to do. >> What I wanted to say : it is rather strange that a database tells >>you : you cannot win with this move, >> but I can't tell you if it is a draw or a loss. >>In the example I gave, the losing move was obvious. But what to do >>if it is not clear? What is the advantage of using a database if the >>engine has to make himself the difference between losing and drawing >>moves? > >The database cannot tell For some endgames like KRP vs KR if it is a win for the >weaker side or a draw but can tell if it is a win for the stronger side or a >draw. > >Usually wins for the weaker side are short wins so the right winning move for >the weaker side is usually obvious. > >The usual problem is to find the right way for the stronger side to win and here >the tablebases can help > >best Regards >Uri Hello again Uri, I'm puzzled by your remarks concerning the Fritz CD ROM. You seem to be calling it a "database" and differentiating it from a "tabelbase". I'm not sure what the difference is but I can't follow your reasoning that the "database" cannot tell if it is a win for the weaker side but can tell if it is a win/draw for the stronger side. It seems to me that all of this information is in the "database". The Fritz engine is certainly not making this decision with "zero" search time. If you look at the move list in Fritz when using the CD ROM it shows (0) 50. Rd6 or something like that. Which means it's a draw when playing 50.Rd6. If you see (14) 50. Rd6 it means it's a win and conversion in 14 moves. It does not matter which side you are playing it is a win in 14 for one side and a loss in 14 for the other(Conversion in 14). This stuff is comming right off the CD ROM not from Fritz or Junior. Usually you will see something like this: (13) 50. Ra8 (12) 50. Rc7 (12) 50. Rd7 (12) 50. Kb7 (11) 50. Rb7 This is what it looks like for the losing side. The best move is at the top and gives the maximum number of moves to conversion which therefore is the best move if your intention is to last as long as possible. It's just the opposite for the winning side. The numbers in the () increase when going down the list. For example: (11) 50...Rf5 (13) 50...Re5 (14) 50...Kh6 This means it 11 moves to conversion startin with 50.... Rf5 with best play. So why would you say the "database" cannot tell if it is a win for the weaker side? Do you mean it cannot tell when there are errors on the CD ROM? In that case it can't tell for either side since the data in the "database" is wrong. Please explain to me what you mean. Jim Walker
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