Grünfeld Defence Powerbase 2021 is a database and contains 10826 top-class games from Mega 2022 and the Correspondence Database 2020, of which 1136 are annotated.
The major part of the material on which the Grünfeld Defence Powerbook 2021 is based comes from the engine room of playchess.com: 232 000 games. To this imposing mass we have added another 70 000 games from Mega and from correspondence chess.
For the Slav and Semi-Slav Powerbook 2021 the ratings average was set at 2400. 1.76 million games from the engine room of playchess.com met this threshold, to which were added over 80 000 games played by humans.
Slav and Semi-Slav Powerbase 2021 is a database and contains a total of 10 610 games from Mega 2021 or the Correspondence Database 2020, of which 1030 are annotated.
