I don't use database of 2500-2700 people because there are database of 3500+ rated machine available now. Actually these books are built with very deep analysis, the rating and accuracy is probably 3700- 3800+. The good point is they are free and currently updating.
chess opening book ctg free download
Here are the free HIARCS Chess Opening Books. We will be updated periodically as new books are released. To access the latest and strongest HIARCS Chess Opening Books please purchase to our opening book update product.
HIARCS professional books in our chess opening book download product are many times larger with the latest human, correspondence and computer games. They are the strongest available opening books and are at least 100 Elo stronger than the free chess opening books hosted here.
iPhone, iPod Touch or iPad customers can now download custom books from this page for their device. Book customers should refer to the customer download page for our full tournament book in HBG format.
Please note for top performance in play you should allow HIARCS to use its own engine book which is included in the HIARCS installation and updated via the book access product. To ensure HIARCS is using its own engine book, you should turn off or unload any GUI books being used by the chess GUI you are using.
CTG, (ChessBase Opening Tree of Games)an opening book format by ChessBase, supported by their Fritz GUI and ChessBase GUI, and therefore used by all chess engines compatible with these commercial user interfaces. While the book format is proprietary, a partial specification was leaked for the purpose of interoperability [1]. Each Chessbase book consists of four files, the binary CTG file contains the real data, the INI text file provides auxilliary information, the CTB file some kind of bitmap over free pages in the CTG file, and the CTO file, containing a lookup table into the CTG file for fast indexed access. Only White to move positions along with its moves, annotations and engine recommendations, and statistics are stored, probing black positions requires color flipping, of course including en passant square and castling rigths. Further, if the white king is on files a-d, and neither side has any castling rights remaining, the board is mirrored horizontally. The CTG file is organized in 4KiB pages, the first page contains header information such as the number of games, followed by consecutive data pages. Each data page starts with an header specifying the number of positions and bytes per page, followed by a list of a variable length position entries.
I have the up-to-date Mega Database 2020 and I filter all games with an B20-B99 ECO, which gave me roughly 1.2M games. Then I followed -kb/content/details/725/Creating%20your%20own%20opening%20books (You create a database, and then you import the games from this database in the blank opening book, et voilà.)
I first included variations and set length to 30 (gave me three ct* files summing up to 3GB) for then choosing not to include variations and set length to 20 (gave me three ct* files summing up to 2GB). (The 926 number is from the ChessBase tutorial.) Regarding the size (2-3GB) of the set of produced ct* files, it is for instance comparable to the size of the ChessBase Sicilian Najdorf 2020 opening book (which has only 3M games though), so that the problem that I have is not caused by a potentially too big opening book nor an opening book tree base on a number of game that is way too big.
The problem that I have is that so far, I only used official chessbase opening books (with Fritz on PC or DroidFish on android) and when I load such an official opening book, whatever may its size be, the engine plays instantaneously (because browsing the opening book is extremely fast for the GUI they're it, or for them).
With the opening books I created using ChessBase advices above, the engine don't play instantaneously, hence browsing though the opening book tree takes quite a long time. (For instance 1.e4 took half a minute when I play as black and the engine as white.)
How different are official ChessBase opening books from the one created with the ChessBase tutorial ? I guess that for opening books from the first category, the trees are somehow "optimized" when they aren't for opening books from the second category. 2ff7e9595c
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