BTW, Howard, I've been through your permutation code, and found something's missing!

I extracted all but the code to generate the permutations and turned it into this independent script:

code:
BREAK ON
 
Dim $a, $b, $c, $d, $, $x, $y
 
$a = 'a'
$b = 'b'
$c = 'c'
$d = 'd'
 
for $y=1 to 4
  for $x=1 to 4
    ? ""+$a+$b+$c+$d
    $ = $b
    $b = $c
    $c = $d
    $d = $
  next
  $ = $a
  $a = $b
  $b = $
next
I thought it would only do 16 of the 24 permutations, but it does even less!!
It only does 12 "diferent" permutations, as 4 are repeated!!
This means that you test only HALF the valid permutations!!!

code:
It.  Permutation
 01  abcd
 02  acdb
 03  adbc
 04  abcd
 05  cadb
 06  cdba
 07  cbad
 08  cadb
 09  dcba
 10  dbac
 11  dacb
 12  dcba
 13  bdac
 14  bacd
 15  bcda
 16  bdac
Putting it another way, where the number(s) in front are
the iteration number(s) where that sequence is visited:

code:
abcd 01 04
abdc 
acbd
acdb 02
adbc 03
adcb
bacd 14
badc
bcad
bcda 15
bdac 13 16
bdca
cabd
cadb 05 08
cbad 07
cbda
cdab
cdba 06
dabc
dacb 11
dbac 10
dbca
dcab
dcba 09 12
This means, or so I think, that you never test the
following permutations:

abdc acbd adcb badc bcad bdca cabd cbda cdab dabc dbca dcab

So, it's very likely that your code would fail on things like: 6143 and 6451.

[ 24. September 2002, 00:41: Message edited by: Fernando Madruga ]
_________________________
Later,   [b]Mad[/b]ruga