## [lit-ideas] Re: Try a Logic Problem

• From: "Phil Enns" <phil.enns@xxxxxxxxxxx>
• To: <lit-ideas@xxxxxxxxxxxxx>
• Date: Thu, 22 Jun 2006 19:30:39 -0400

Paul Stone:

The blind guy has a white hat on.

1) Prisoner 1 can see both 2 and 3's hats. He doesn't know what his hat
is, therefore, their hats have to be white and red or two whites.

2) Prisoner 2 can see both 1 and 3's hats. He doesn't know what his hat
is, therefore 1 and 3 must be wearing either W/W or R/W.

3) Since neither prisoner 1 or 2 knows which colour hat they have on,
they must BOTH be wearing red ones because, if 3 had a red hat on,
prisoner #2 would KNOW that he has a white one on -- since both 2 and 3
can't both have Reds or number 1 would know that he has a white one on.

Phil:

The problem with 3) is that they could all be wearing white hats.  3) is
also a mess grammatically.

Here is the version I emailed Walter earlier.  I am not sure if it made
it through his spam blocker.

1. Since there are only two red hats, if either P1 or P2 can see two red
hats they would know their hat is white.
2. Therefore, both P1 and P2 see a white hat.
3. If P2 can see that P3 is wearing a red hat, knowing that P1 must see
a white hat, P2 would know that he is wearing a white hat.
4. Since P2 doesn't know what hat he is wearing, P3 knows that he is
wearing a white hat.

Sincerely,

Phil Enns
Toronto, ON

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