The Sicilian Paulsen Powerbook was based on an Elo average of at least 2400. Thus 43,000 games from the Mega and from correspondence chess exceeded the Powerbook's input threshold, plus 426,000 games from the engine room of Schach.de. The different designations - 4...a6 for the Paulsen Variation, 4...Nc6 for Taimanov Variation - in English generally referred to as Kan Variation - do not play a role in this Powerbook, because it is based on games from the complete range B40-B49. Transitions from one range to the other are very frequent and are well represented by the Powerbook.
In the Powerbook 4...Nc6 clearly dominates. However, ...a6 is usually played immediately afterwards - if not on move 5, then on move 6. A popular move sequence is 4...Nc6 5.Nc3 Qc7 6.Be3 a6 7.Qd2 Nf6 8.0-0-0
The most played and most popular move in the engine room 8...Bb4 has lost popularity among top players (in favour of 8...Be7). After 9.f3 Ne5 White can probably also play 10.g4!? instead of the theoretical move 10.Nb3, which can be deeply studied in the Powerbook, on the basis of over 17,000 games. Instead of 7.Qd2, 7.Be2 is even more common, thanks to the games from the engine room. After 7...Nf6 8.0-0 Black must be ready for the Scheveningen with 8...Be7 (White too, of course). However, the Powerbook has over 100,000 games with 8...Bb4 (also the most popular move in human chess). And instead of the overanalysed 9.Na4, 9.Nxc6 bxc6 10.f4 comes into question. Of course, the most exciting move would be 10...Bxc3 11.bxc3 Nxe4 (11...c5 is safer, but should not equalise either).
Now 12.Bd3 is probably the strongest, after 12...Nf6 13.Qf3 Black is in for tough times.