In an island peopled by Knights (who always say the truth) and Liars (who obviously always lie), two persons spoke about each other.
A said: "B would say I lie."
B said: "That is true."
Can anything be deduced as to what kind is each of them?
This is straight binary, with only two digits, and can be solved with brute force.
Say if a person is a knight, his value is 0 and a liar's value would be 1. Thus, all possible combinations are:
A B
0 0 A would know B is a knight and would not
make the first statement. FALSE
0 1 The first statement is possible, but the
second is not. FALSE
1 0 The first statement would be true, but
would not be spoken by a liar. FALSE
1 1 "B would say I lie": B is a liar and would
say otherwise, thus making the first
statement a lie and possible. "That is true"
refering to the first statement, would
be a lie. Thus for the case of both A and B
being liars, these statements are possible.
So without any further ado, I would say that A and B are both liars...
Short discussion
