Kasparov-Karpov 1987 riddle solutions

In the fourth world championship match between Garry Kasparov and Anatoly Karpov, played in Seville in 1987, the score was 12–11 in Karpov’s favor, putting Kasparov in a must-win situation to retain his title. This game was the subject of our previous article. We invited our readers to analyze with us, to solve a historical riddle. Here are the results.