Xixi Logic Seminars #29

Speaker: Prof. Hans van Ditmarsch (LORIA / CNRS; IMSc)
Date & Time: 29 March 2016 (Tuesday), 15:55 – 17:30
Place: 1A-214, East Teaching Building, Zijingang campus, Zhejiang University

Logic puzzles

In this seminar I will introduce some logic puzzles having to do with knowledge and ignorance. People talking to each other can see contradictory things. That is not so surprising. But what is puzzling is that this may after all not be contradictory. An example is the following puzzle:

Anne and Bill are each going to be told a natural number. Their numbers will be one apart. The numbers are now being whispered in their ears. They are aware of this scenario. Suppose Anne is told 2 and Bill is told 3. The following conversation between Anne and Bill now takes place:
Anne: “I do not know your number.”
Bill: “I do not know your number.”
Anne: “I know your number.”
Bill: “I know your number.”

I will explain in this lecture why Anne and Bill can be saying the truth all the time and still are not contradicting themselves. I will also give other logic puzzles. For more information on such puzzles, please see http://personal.us.es/hvd/lightbulb.html