In the Land of Knights and Knaves [LKK], Knights told the truth,
and Knaves always lied. When the rare averitas flu virus infected
some of the inhabitants, their behavior was reversed: sick Knights
began to lie, and infected Knaves had to tell the truth!
Your job is to find out the ones who have been infected so they can
be given the costly AFV vaccine. You've just dealt with six of them,
and now a group of ten LKK citizens is brought to your
office, and they venture the following information:
Who are the sick ones? and who are the Knights?
01. Alan: Jack is lying, or he's a Knight; but not both.
02. Bervin: Jack is lying, or I am a Knave; but not both.
03. Clarence: Harry might be a Knave, but only if he is well. Harry is well.
04. David: Harry might be a Knave, but only if he is sick.
05. Evan: Alan might be a Knave, but only if he is well.
06. Bervin: Alan might be a Knave, but only if he is sick. Alan is sick.
07. Fred: If Harry is sick, then Jack is lying.
08. Fred: Alan is lying.
09. George: Fred is lying.
10. George: No fewer than 4 of us are lying.
11. Evan: No more than 4 of us are Knights.
12. Alan: I am a Knight.
13. Harry: I am a Knave.
14. Ingolf: None of our statements is a paradox.
15. Jack: If 2+2=5, then New York is a small city.
Edit #1: Numbering the statements, to make discussion easier.
Edit #2: Bervin and Clarence change their stories, slightly. [thx to s54 and wb!]
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If you like this type of puzzle, here are some others, recently posted to this forum.
Knights and Knaves get the flu [bononova]
Honestants and Swindlecants: The Delegation [octopuppy]
Knights, Commoners & Knaves [roolstar]
Four Knight and Knave problems [bonanova]
knights and liars [2] [bonanova]
knights, knaves and liars [bonanova]
3 Princess Puzzle [O'Beckon]
The Barber of Honestants and Swindlecants [spoxjox]
The liar, the truth teller....and the random answerer [Martini]