Opening Books

Method: Openings in each book come from the Caissabase database of 5.4M human games. All unique PGN move sequences were extracted and counted for a given ply, then filtered to remove less common move sequences resulting in the same final position (FEN). The resulting openings were tested for imbalance with 100 nodes of a large Leela net (net 65100) or 1000 nodes of a small net (703810). All opening books appear in order of human popularity, with most popular first. Because the source is so broad, later entries in each book are very odd but you can readily edit them by hand to cut off wherever you want.

First set of books are raw, in the form of FEN; PGN moves; Q. Anyone with a little programming or spreadsheet experience can turn those into books of your choice.

Approximate Q guide:

1. openings with abs(Q) 0.0 to 0.25 are balanced (roughly between -30 and 30 centipawns on the Stockfish scale)
2. openings with abs(Q) 0.25 to 0.4 are unbalanced
3. openings with abs(Q) and over 0.4 are very unbalanced

Main lines of common openings are typically about Q 0.1 to 0.2.

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Raw books:
FEN; PGN moves; Q

• 4-ply book raw

• 6-ply book raw

• 8-ply book raw

• 10-ply book raw

• 12-ply book raw [truncated to 200k most common openings]

• 14 pieces left raw

• 16 pieces left raw

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Tiered books:
Q ranges are absolute value (black or white advantage), standard 7 header PGN format with one added header that gives the Q value, which you can ignore if you wish.

• 4-ply book Q 0.0 to 0.25 [5,432 openings]
• 4-ply book Q > 0.25 [1,393 openings]
• 6-ply book Q 0.0 to 0.25 [27,772 openings]
• 6-ply book Q 0.25 to 0.40 [4,485 openings]
• 6-ply book Q > 0.40 [3,005 openings]
• 8-ply book Q 0.0 to 0.25 [82,713 openings]
• 8-ply book Q 0.25 to 0.40 [14,852 openings]
• 8-ply book Q > 0.40 [10,184 openings]

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Tiered endgame books:

• 16 piece Q < 0.6 [725,678 "openings"]