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Fred: John is lying

Bob: Fred is lying

John: Fred is lying or Bob is lying

"or" is inclusive

I got that John and Bob are saying the truth while Fred is lying, but i'm not sure if it's correct (someone else that did it also got the same).


marked as duplicate by PerpetualJ, rhsquared, QuantumTwinkie, Quintec, MikeQ Oct 18 '18 at 3:29

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  • $\begingroup$ @RobertS. no, as Fred says JOHN is lying $\endgroup$ – PotatoLatte Oct 17 '18 at 15:23
  • 1
    $\begingroup$ @RobertS. slightly different, I think $\endgroup$ – Hugh Oct 17 '18 at 15:24
  • $\begingroup$ @JonMarkPerry it's the same question but the statements are different. People already answered it and I only realised that I wrote the statements wrong a few hours ago. $\endgroup$ – xKetjow Oct 17 '18 at 15:47

In these sort of questions, if someone says that someone else is lying, then between the two, exactly one is lying (a truth teller wouldn't accuse another truth teller of lying, because that would be a lie, and a liar wouldn't accuse a liar of lying, because that would be telling the truth). Since Bob says that Fred is lying, exactly one of them is lying. Either way, John is telling the truth, which means that Fred is lying, and Bob is telling the truth.

  • $\begingroup$ So in other words, Bob and John are saying the truth while Fred is lying? $\endgroup$ – xKetjow Oct 17 '18 at 18:13

Your conclusion is



If Bob is telling the truth, then John is also telling the truth, which is correct.


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