The fourth book of the series is devoted to opening schemes, which arise after the moves 1.e4 d6, or 1.e4 g6. These systems have proved their right of existence, despite the numerous attempts to refute them once and for all. The positions are so diverse strategically and so rich tactically that they deserve a separate volume. Black avoids early clashes and narrows his sphere of influence to only three ranks. However, his harmonious development enables him to attack often Whites powerful center successfully. The 14th World Champion Khalifman recommends against the majority of the flank systems schemes with f2-f4, which provide additional control over the center. He included in this fundamental work plenty of new and original analyses which surely will cause Black a lot of trouble!