Which Alice?

Case 1—Both said yes
Solutions to the Puzzles
TABLE 1
Case 2—A said no and B said yes
Case 3—A said yes and B said no
Case 4—Both said no
Now, we are given that after A and B answered the judge's
questions, the judge knew that C was not the spy. If Case 3 were the
one that occurred, then the judge couldn't know whether C was a
spy or a knight. If Case 4 occurred, the judge couldn't know
whether C was a spy or a knave. But the judge did know that C
wasn't the spy. Therefore, Case 3 and Case 4 are ruled out; so it was
either Case 1 or Case 2.
Now, the judge knows that A spoke the truth when he said that C
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