I met two natives on an island - Benny and Lenny. They are either a knight, a liar or a knave. Knights always tell the truth, liars always lie and knaves alternate between truth and lie. They tell me this:
Benny : We are both of the same type.
Lenny : I am a knave.
Benny : Lenny is a liar.
A knight then tells me what Lenny is. From this I was able to work out what they were.
What are Benny and Lenny?
Most apparent is that Lenny's statement precludes him from being a knight, which in turn precludesBenny from being a knight by his first statement, so we're dealing with knaves and liars only. Assume Lenny is a liar, this means since Benny's second statement is true, he must be a knave and therefore his first statement would have to be true. However this yields a contradiction because Benny states he is of the same type as Lenny, a liar. Thus it must be that Lenny is a knave, which means Benny's second statement is false, if Benny were a liar then it would be a contradiction because his first statement would be true, therefore Benny is a knave also.
Couple of Knaves
