A traveler passing through the land of liars and knights stops in at a pub, where he meets a group of six friendly locals. Their stories all are funny, but he doesn't know which ones to believe, so he asks them (tactfully) who the liars and knights are in the group. They make one statement each:
Amery: Cuthbert and Fredo are both liars.
Brant: Everard and Fredo are both knights.
Cuthbert: Brant is a liar and Everard is a knight.
Derek: Amery and Brant are both liars.
Everard: Cuthbert and Derek are both knights.
Fredo: Derek is a liar and Amery is a knight.
Which of the men are liars, and which are knights?
Remember: only part of a logical AND statement needs to be false for the entire statement to be false.
Amery, Brant and Fredo are liars. And Cuthbert, Derek, and Everard are knights.
I basically gave it a trial and error run, by first assuming that Brant is a knight (because he pointed to two more knights). I then evaluated all the statements leading from there. He says that Everard and Fredo are knights. But they contradict eachother, so they can not both be knights, thus making Brant a liar. I then went to the next iteration in assuming that Cuthbert is a knight (because he already correctly states that Brant is a liar). C says that E is a knight, which in turn turn says that C and D are knights. So far so good. D says that A and B are liars (we know B is). A says that that C is a liar (which is false according to our assumption), making it a lie in this case. As for F saying D is a liar and A is a knight, makes him a liar.
Thus, A, B and F are liars. And C, D, and E are knights.
Possible solution
