A researcher in computer science and artificial intelligence, professor DennisShasha teaches at the Mathematics Institute at the University of New York. He is the author of Jeux d'Esprit et enigmes mathematiques and Les adventures du Dr. Ecco (Ed. Odile Jacob, 1995).Here is the next chapter in the great adventures of Dr. Ecco.Jacob Ecco has disappeared. His friends, the beautiful philosophy professor Evangeline Goode and the mathematician Justin Scarlett, are hot on the trail. An ever-compounding adventure rich in enigmas ensues, from bullfights in Uruguay, a bank hold-up in Ireland and bacteriological warfare in Africa to the theft of an American ballistic nuclear submarine. Will the heros succeed in locating Ecco and above all in stopping the wicked Baskerhound in his insane plots?The reader is invited to help solve the mystery: each enigma that is resolved advances the story. The book counts forty five conundrums in all, inspired by modern mathematics and computer science. No prior knowledge is necessary-- a paper and pencil will suffice. And, of course, intuition and imagination. Answers may be compared with the solutions provided at the end of the book-- it's your turn to play!