Chess opening are so complex and theoretical that amateur players will have trouble understanding them. An example is the Perenyi Attack of the Sicilian Defense (see diagram) which yields an immensely complicated and tactical position that even strong players have difficulty handling, and that is beyond the comprehension of most amateurs. Major changes in the rules of chess in the late fifteenth century increased the speed of the game, consequently emphasizing the importance of opening study. Thus, early chess books, such as the 1497 text of Luis Ramirez de Lucena, present opening analysis, as does Pedro Damiano (1512), and Ruy López de
World Chess Championship 2014 an easily drawn endgame. The ninth game was played on 20 November 2014. The opening was the Berlin Defence of the Ruy Lopez. The game was drawn due to threefold repetition on the 20th move. This game included no original moves. The draw meant that Carlsen was closer to converting his 1-point lead to a match win, though Anand seemed satisfied to draw early and focus on his two remaining games with the white pieces. Although a short draw at 20 moves, this game is far from the shortest in match history; a pair of 10-move draws sealed Petrosian's match