1. Liar liar

2. Alex says: "Cody is a knave." Brook says: "Alex is a knight."
There are three people (Alex, Brook and Cody), one of whom is a knight, one a knave, and one a spy.
The knight always tells the truth, the knave always lies, and the spy can either lie or tell the truth.
Alex says: "Cody is a knave."
Brook says: "Alex is a knight."
Cody says: "I am the spy."
Who is the knight, who the knave, and who the spy?
The way to solve one of these puzzles is to say:
‘lets suppose that alex is the knave….’
And then work through the logic statements to see if that could be true. There are only three things Alex could be and so you will find a solution fairly soon. The same strategy can be applied to the next question.
Alex is a Knight
Brook is a Spy
Cody is a Knave

3. They are brought before a judge who wants to identify the spy.
There are three people (Alex, Brook and Cody), one of whom is a knight, one a knave, and one a spy.
The knight always tells the truth, the knave always lies, and the spy can either lie or tell the truth.
They are brought before a judge who wants to identify the spy.
Alex says: "I am not a spy."
Brook says: "I am a spy."
Now Cody is in fact the spy. The judge asks him: "Is Brook really a spy?"
Can Cody give an answer so that he doesn't convict himself as a spy?
Hint: It’s a yes or no answer.
Solution:
Cody should answer "No". That means that he could either be lying or not.