what situation is right I have two categories of people, the reliable and the liars.The reliable telling always the truth,the liars always telling lies. One visitor meets both of them:
A declares: "I and B are the same." B declares : "From us no one is reliable."
What situation is true?
a)both are liars
b) the A is liar and the B reliable
c)both reliable
d)A is reliable and B is liar
I beleive is the b) A is liar and the B reliable
Am I right?
 A: It is not quite clear which group B is talking about when he says "From us". Perhaps "From us two, A and B"? Or "From my category"?
However, in any case: B is claiming to belong to (some) group that is all liars. If B is reliable, then his claim would need to be true, so B would need to be a liar also. Now that is surely a contradiction, isn't it? So it is not possible that B is reliable. He must be a liar.
Since B is a liar, his statement must be false, so the group is not all liars; it must contain at least one reliable person. Well, not B (he is a liar), but someone else.
Now about A. If he is reliable, then he is telling the truth, and he is of the same category as B, that is a liar. Contradiction. What about the other possibility? If A is a liar, then he is lying, and in reality he is of a different category than B; since B is a liar, A is reliable. Again a contradiction.
As it turns out the situation is impossible.
A: Now suppose $A$ is reliable then the statement "I and B are the same" is true. This implies $B$ is reliable. However, if $A$ was a liar then $A$ and $B$ are different thus $B$ is realiable. Therefore irrespective of what $A$ is $B$ is realiable. But if $B$ is reliable $B$ is also not reliable(from $B's$ declaration itself). Thus it's a contradicting situation.
