A very high average Elo of at least 2450 was used as a basis. A total of 780,000 games with the ECO codes D30-D42 as well as D50-D69 form the basis for the Powerbook. The Queen's Gambit Declined is one of the openings with which Black has very good chances of equal play. Hence, it has been used in many world championship matches. It is also popular for the opening books in the engine room of Schach.de for the same reason, which is what gives us so many games with this opening. Statistics are therefore all the more meaningful.
Desktop PC or Notebook, 2 GB RAM, Windows 11, 10 or 8.1, DVD-ROM drive (if ordered with Postal Delivery), ChessBase 16 or 15, Internet access (downloads).
Rarely does a powerbook “show the way” in the actual opening moves themselves, but this is an exception. After 1.d4 d5 2.c4 e6 3.Nc3 Nf6 it is a matter of personal taste whether to play 4.Bg5, 4.cxd5 or 4.Nf3 (and then e.g. 5.Bf4). Discoveries have to be made far along the opening tree. For example, look at the exchange variation 4.cxd5 exd5 5.Bg5 c6 6.e3. Here the endgame after 6...Bf5 7.Qf3 Bg6 8.Bxf6 Qxf6 9.Qxf6 gxf6 poses a problem for White - how can they gain some advantage? After 10.Nf3, The Powerbook gives Nd7.
11.Be2 is then the most played move (instead of 11.Nh4 in the Mega database) - with solid scoring and statistics based on over 600 games.