simultaneous assignment

[Gary Duzan]

In article <RAN5g.2037$No6.43926 at news.tufts.edu>,
John Salerno  <johnjsal at NOSPAMgmail.com> wrote:
>bruno at modulix wrote:
>
>> Now if I may ask: what is your actual problem ?
>
>Ok, since you're so curious. :)
>
>Here's a scan of the page from the puzzle book:
>http://johnjsalerno.com/spies.png
>
>Basically I'm reading this book to give me little things to try out in 
>Python. There's no guarantee that this puzzle is even conducive to (or 
>worthy of) a programming solution.

   Exhaustive search is quite practical for this problem:

[(x,y,z,w) for x in (True, False)
	   for y in (True, False)
	   for z in (True, False)
	   for w in (True, False)
	   if spy(x,y,x,w)]

Given the appropriate spy() function, this will return a set of
values for the truthful (logically coherent) spy and nothing for
the other spy. The details are left as an exercise for the reader.
:-)

					Gary Duzan
					Motorola CHS