[techtalk] This talk of N-ary trees and other things...

[psyche]

On Fri, 23 Mar 2001, David Merrill wrote:

> On Fri, Mar 23, 2001 at 04:54:47PM -0800, Nancy Corbett wrote:
> > 
> > ---
> > Knights and Knaves problem. 
> > 
> > Suppose you visit a strange island with three types of people. Knights,
> > who always tell the truth, Knaves, who always lie and Normals who
> > sometimes lie and sometimes tell the truth. It is also the custom that
> > normals marry only normals, and knights marry only knaves. 
> > You meet two couples, Mr. and Mrs. Smith and Mr. and Mrs. Brown. They tell
> > you the following: 
> > 
> > Mr. Brown: Mr. Smith is a knight. 
> > Mrs. Brown: My husband is right, Mr. Smith is  a knight. 
> > Mrs. Smith: That?s true, my husband is indeed a knight. 
> > 
> > Can you determine which type each person must be? Explain.
> > ---
> 
> Hmmmmm.
> 
> Mr. and Mrs. Brown are normals. A knight and a knave would not agree.
> If Mrs. Smith were a knave, her husband would be a knight and she
> would not call him so. And if she were a knight, she would not call
> her knave husband a knight! So are they *all* normals?
> 

That's what I came up with--all normals, and all lying, too.  I love these
things. :)

psyche