The Betrayal

[sljohn04]

my mind is rusty, help... i dont get the "but only AFTER the second stop they all know that there are three marked helmets in the train... (because no one got off the train on this stop)" can i have further explanation please..?

[Strutter]

Hmmm long time since I explained this one but here it goes:

Let's say there are three traitors. We call them:

A
B
C

What you must remember is that they see themselves as not guilty as long as possible as they don't know about being traitors.

When the train leaves:

The soldiers either see 2 or 3 red crosses. "A" sees 2 red crossed helmets. "A" thinks that "B" thinks that he's no traitor and sees only one helmet. "A" thinks that "B" thinks that "C" thinks that he must be the traitor because he sees no other red crosses.

Same line of thinking goes for "B" and "C".

First stop:

No one goes off at the first stop. "A" now thinks that "B" realized that he's the other traitor because "C" didn't go off the train so there must be at least one more red crossed helmet. "A" thinks that "B" and "C" will go off at the next stop.

Same line of thinking goes for "B" and "C".

Second stop:

"B" and "C" don't get off at this stop either. So "A" now realizes that he's the third traitor because there must be at least one more helmet and he only sees 2.

Same line of thinking goes for "B" and "C".

Third stop:
All the traitors get off the train.