A Mensa Problem

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>>>>> "caryle" == caryle clear <cpcj@sprynet.com> writes:

    caryle> | | You are in a room with two doors.  There are two men,
    caryle> one each guarding a | door. One door leads to certain
    caryle> destruction.  The other door leads to | freedom. One man
    caryle> is a liar, never telling the truth.  The other man always
    caryle> | tell the truth.  | | What ONE question can you ask each
    caryle> man and find out which way to safety.  The | same question
    caryle> is asked to both men.  | | Sis Wendy Horn

    caryle> Ok, I'll give it a shot.  Let's just say, for the sake of
    caryle> clarity that there is man A (with door A) and man B (with
    caryle> door B).

    caryle> You ask man A first..."Would person B say that door A
    caryle> leads to freedom?"  "A" says yes, person B would say
    caryle> "yes", door A leads to freedom.

    caryle> You ask man B..."Would person B (himself) say that door A
    caryle> leads to freedom?"  "B" says "yes", which means person A
    caryle> was telling the truth, and therefore, B is lying,
    caryle> ergo...Door A does NOT lead to freedom.

    caryle> **If B says "no".  Then person A was lying, B is telling
    caryle> the truth, ergo, door A still doesn't lead to freedom.

    caryle> For this scenario, door B leads to freedom.

    caryle> NOW...  If A says "no", person B would NOT say door A
    caryle> leads to freedom.  If B says "no", then A was telling the
    caryle> truth and B was lying, ergo, door A does indeed lead to
    caryle> freedom.

    caryle> If B says "yes", then A was lying, and door A still leads
    caryle> to freedom.

    caryle> For *this* scenario, door A leads to freedom.

    caryle> Since you ask each question only once, following this
    caryle> pattern, you would still come to a correct answer
    caryle> regardless of what A said first.  Is that close?
    caryle> Anneliese

What do you do if man A says "I don't know"?  You never stated that
each man knows which door he is guarding -- those nasty unstated
assumptions again!

-- 
--------  "And there came a writing to him from Elijah"  [2Ch 21:12]  --------
Robert Jay Brown III rj@eli.elilabs.com  http://www.elilabs.com 1 847 705-0424
Elijah Laboratories Inc.;  37 South Greenwood Avenue;  Palatine, IL 60067-6328
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