IMPORTANT: Please do not post solutions, hints, or other spoilers until at least 60 hours after the date of this message. Thanks. IMPORTANTE: Por favor, no enviéis soluciones, pistas, o cualquier otra cosa que pueda echar a perder la resolución del problema hasta que hayan pasado por lo menos 60 horas desde el envío de este mensaje. Gracias. IMPORTANT: S'il vous plaît, attendez au minimum 60 heures après la date de ce message avant de poster solutions, indices ou autres révélations. Merci. WICHTIG: Bitte schicken Sie keine Lösungen, Tipps oder Hinweise für diese Aufgabe vor Ablauf von 60 Stunden nach dem Datum dieser Mail. Danke. BELANGRIJK: Stuur aub geen oplossingen, hints of andere tips in de eerste 60 uur na het verzendingstijdstip van dit bericht. Waarvoor dank. VNIMANIE: Pozhalujsta ne shlite reshenija, nameki na reshenija, i voobshe lyubye podskazki v techenie po krajnej mere 60 chasov ot daty etogo soobshenija. Spasibo. Qing3 Zhu4Yi4: Qing3 Ning2 Deng3Dao4 Jie1Dao4 Ben3 Xin4Xi2 Zhi1Hou4 60 Xiao3Shi2, Zai4 Fa1Biao3 Jie3Da2, Ti2Shi4, Huo4 Qi2Ta1 Hui4 Xie4Lou4 Da2An4 De5 Jian4Yi4. Xie4Xie4. ---------------------------------------------------------------- Here's something I've wondered about for several years, but never finished looking into. Consider the 'guess-the-animal' program of regular QOTW #10. Suppose the question tree looks like this: Does it fly? /\ yes / \ no / \ Does it have salmon feathers? /\ yes / \ no / \ carrot fruit bat For some reason, the database records the 'fact' that carrots fly and have feathers. Back around 1994, I had a CGI guess-the-animal program, and people put in all sorts of nonsense like this. If the user is thinking of a sparrow, then the carrot is a little silly, because the game will go like this: COMPUTER HUMAN Does it fly? yes Does it have feathers? yes Is it a carrot? (huh? whatever...) no I give up. What animal were you thinking of? sparrow What is a question that Is it orange? would distinguish a carrot from a sparrow? For a sparrow the answer would be? no And now the tree looks like this: Does it fly? /\ yes / \ no / \ Does it have salmon feathers? /\ yes / \ no / \ Is is fruit orange? bat /\ yes / \ no / \ carrot sparrow But now suppose someone comes along who knows a little bit more about carrots: COMPUTER HUMAN Does it fly? no Is it a salmon? no I give up. What animal carrot were you thinking of? What is a question that ... would distinguish a carrot from a salmon? ... ... Now there will be two carrots in the tree. What I'd like to see is for the computer to recognize that it now has contradictory information about carrots: I give up. What animal carrot were you thinking of? Someone told me before that yes carrots do fly, but you said they didn't. Are you sure? And then the program should amend the database as appropriate, perhaps resulting in: Does it fly? /\ yes / \ no / \ Does it have Is it crunchy? feathers? /\ /\ yes / \ no yes / \ no / \ / \ carrot salmon sparrow fruit bat