Another math puzzle!
We are on the island of knights and burglars. Knights always tell the truth, and burglars always lie. However, there is a spy. Someone who sometimes tells the truth, and sometimes lies. Three people (Alfred, Bertram, and Cedric) have been taken to court, to find out who the spy is. We know that one of them is a knight, one of them is a burglar, and one of them is the spy, we just don't know who's who.
Alfred was called to testify first. He either said that Cedric is a burglar, or he said that Cedric is the spy. Sadly, we don't know exactly what he said.
Then, Bertram was called. He either said that Alfred is a knight, or he said that Alfred is a burglar. Again, we don't know what he said.
Lastly, Cedric was called. He said that Bertram is a knight, or he said that Bertram is a burglar, or he said that Bertram is a spy. Again, we don't know what to said. The court transcriber has been fired, and someone who's better of hearing has taken up the position.
Luckily, the judge *did* hear exactly what everyone said, and was able to determine who the spy is.
The story as I've posted it so far, has also been told to a recreational mathematician. He started pondering on the problem, but could not determine who the spy is. Then an insider told him what Alfred's exact words were. With this additional knowledge, he was able to find out who the spy is.
And now to you: who is the spy? Alfred, Bertram, or Cedric.
Alfred was called to testify first. He either said that Cedric is a burglar, or he said that Cedric is the spy. Sadly, we don't know exactly what he said.
Then, Bertram was called. He either said that Alfred is a knight, or he said that Alfred is a burglar. Again, we don't know what he said.
Lastly, Cedric was called. He said that Bertram is a knight, or he said that Bertram is a burglar, or he said that Bertram is a spy. Again, we don't know what to said. The court transcriber has been fired, and someone who's better of hearing has taken up the position.
Luckily, the judge *did* hear exactly what everyone said, and was able to determine who the spy is.
The story as I've posted it so far, has also been told to a recreational mathematician. He started pondering on the problem, but could not determine who the spy is. Then an insider told him what Alfred's exact words were. With this additional knowledge, he was able to find out who the spy is.
And now to you: who is the spy? Alfred, Bertram, or Cedric.