84. 

Suppose the prosecutor from the previous problem made the following two statements in court:

1) Either $\mathrm{X}$ is guilty, or $\mathrm{Y}$ is guilty.
2) $X$ is not guilty.

What conclusion would you draw based on these statements?
84. If the accuser were a liar, then
1) X and Y would both be guilty;
2) X would be guilty.

And in this case, we would again arrive at a contradiction. Therefore, the accuser is a knight, X is not guilty, and Y is guilty.