You meet four people. Their names are Gladys, Kate, Tom, and Tim. Each one is either a knight or a liar. They say the following statements.
Gladys:Kate and Tom are both liars.
Kate:Tim is a knight.
Tom:Gladys is a knight and Tim is a liar.
What are Gladys, Kate, Tom, and Tim?
If Gladys were a knight, Kate and Tom would both be liars; then per Kate's lying, Tim would be a liar; and that would make both parts of Tom's statement correct, contradicting his being a liar. So Gladys is a liar and Kate and Tom are not both liars.
Since Gladys is a liar, so is Tom, and so to make Gladys' statement false, Kate must be a knight, and therefore also Tim.
So Kate and Tim are knights, while Gladys and Tom are liars.
But if Gladys were a Knight, there'd be Pips involved.

Posted by Charlie
on 20111129 00:09:26 