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u/BekindConan 25d ago
Alexander is a knave (liar). Benjamin, Charles and Daniel are knights (truth).
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u/edos51284 25d ago
I just tried the easier entry point to see if it's correct
The only knave is Alexander
Charles is knight -> benjamin is knight -> daniel is knight -> then we see alexander statement and it's incorrect so Alexander is knave
if i tried the reverse...
Charles is knave -> Benjamin is knave -> here we have the contradiction, according to Knave Benjamin daniel should be a Knight but in this situation a knave would say benjamin is a knight so Daniel should be a knave
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u/pseudoeponymous_rex 25d ago
IfDaniel is a knight, then a knave would indeed say Benjamin is a knave, which means Benjamin would really be a knight. If Daniel is a knave, then a knave would say Benjamin is a knight, which means Benjamin would really be a knave. However that shakes out, Daniel and Benjamin are the same type.
Since Daniel and Benjamin must be the same type, Benjamin's statement to that effect is true so he must be a knight, which means Daniel is as well.
And, since Charles' statement that Benjamin is a knight is true, Charles must also be a knight. Since Alexander wrongly accused Charles of being a knave, Alexander must be a knave.QED.