Advances in artificial intelligence 4th Hellenic Conference on AI, SETN 2006, Heraklion, Crete, Greece, May 18-20, 2006 proceedings - Antoniou, G. (Grigoris); Ποταμιάς, Γιώργος; Σπυρόπουλος, Κωνσταντίνος (Springer, 2006)