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Database storage methods
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Ronald de Man



Joined: 28 Feb 2012
Posts: 908
PostPost subject: Re: Database storage methods    Posted: Sat Mar 10, 2012 11:45 pm Reply to topic Reply with quote
Edmund wrote:
Furthermore I disagree with Bob regarding the "Most just store a huge file of zobrist hash signatures.". When talking about engines here I suppose you are describing opening books and not databases in general. The problem with this method here is that it invites unwanted transpositions.
e.g. after 1. e4 e5 2. Nf3 a6 3. Bb5 the opening book would suggest the transposition into the well known line with Nc6.
The most streight forward countermesure is to not only calculate hash values of positions but also add the move into the equation.

From rgcc (10/5/96):
hyatt wrote:
To solve your problem above, in tournament mode Crafty uses a short search
of all non-book positions to look for this. It happens lots of times, and
has been the subject of discussion for years. Example:

1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 Ba4

game goes:

1. e4 e5 2. Bb5 a6 4. Nf3 and black promptly plays Nc6 rather than
ripping the bishop, because Nc6 goes back into book. The short search
solves this completely because it would notice that there's a move that
seems to win material at a fairly quick depth, so crafty ignores the
transposition back into book and does a normal search. If the move wins
the piece after a long search, it rips it...

Whether this is still accurate after more than 15 years, I do not know Wink
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Subject Author Date/Time
Database storage methods david nash Thu Mar 08, 2012 10:56 am
      Re: Database storage methods Ed Schroder Thu Mar 08, 2012 11:59 am
            Re: Database storage methods Julien MARCEL Thu Mar 08, 2012 12:33 pm
                  Re: Database storage methods david nash Thu Mar 08, 2012 12:43 pm
                  Re: Database storage methods Martin Sedlak Thu Mar 08, 2012 1:00 pm
                        Re: Database storage methods Julien MARCEL Thu Mar 08, 2012 1:13 pm
                              Re: Database storage methods david nash Thu Mar 08, 2012 1:32 pm
                              Re: Database storage methods Martin Sedlak Thu Mar 08, 2012 1:45 pm
                                    Re: Database storage methods Julien MARCEL Thu Mar 08, 2012 1:51 pm
                        Re: Database storage methods Ed Schroder Thu Mar 08, 2012 3:42 pm
                  Re: Database storage methods Ed Schroder Thu Mar 08, 2012 3:46 pm
                  Re: Database storage methods Robert Hyatt Thu Mar 08, 2012 10:54 pm
                        Re: Database storage methods Julien MARCEL Thu Mar 08, 2012 11:53 pm
                              Re: Database storage methods Robert Hyatt Fri Mar 09, 2012 12:18 am
                              Re: Database storage methods Edmund Moshammer Fri Mar 09, 2012 12:51 am
                                    Re: Database storage methods H.G.Muller Fri Mar 09, 2012 9:29 am
                                          Re: Database storage methods Don Dailey Sat Mar 10, 2012 10:25 pm
                                                Re: Database storage methods Edmund Moshammer Sun Mar 11, 2012 12:27 am
                                                      Re: Database storage methods Don Dailey Sun Mar 11, 2012 5:25 am
                                    Re: Database storage methods Don Dailey Sat Mar 10, 2012 10:44 pm
                                    Re: Database storage methods Ronald de Man Sat Mar 10, 2012 11:45 pm
            Re: Database storage methods david nash Thu Mar 08, 2012 12:40 pm
      Re: Database storage methods H.G.Muller Thu Mar 08, 2012 4:36 pm
            Re: Database storage methods david nash Thu Mar 08, 2012 5:03 pm
                  Re: Database storage methods H.G.Muller Thu Mar 08, 2012 5:28 pm
                        Re: Database storage methods david nash Thu Mar 08, 2012 8:48 pm
      Re: Database storage methods Harald Lüßen Thu Mar 08, 2012 8:45 pm
            Re: Database storage methods david nash Thu Mar 08, 2012 8:51 pm
      Re: Database storage methods Nguyen Pham Thu Mar 08, 2012 10:39 pm
      Re: Database storage methods Vincent Diepeveen Sun Mar 11, 2012 6:41 am
            Re: Database storage methods david nash Sun Mar 11, 2012 4:49 pm
                  Re: Database storage methods Vincent Diepeveen Sun Mar 11, 2012 4:58 pm
                        Re: Database storage methods david nash Sun Mar 11, 2012 5:51 pm
      Re: Database storage methods Vincent Diepeveen Sun Mar 11, 2012 7:03 am
            Re: Database storage methods Vincent Diepeveen Sun Mar 11, 2012 7:21 am
            Re: Database storage methods Edmund Moshammer Sun Mar 11, 2012 9:21 am
                  Re: Database storage methods Vincent Diepeveen Sun Mar 11, 2012 3:41 pm
                        Re: Database storage methods david nash Sun Mar 11, 2012 5:08 pm
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