qscgz wrote:I found 46656 solutions ("rcc9s") , to place 9 queens
(or whatever) into a 9x9 square , such that no two queens are in
the same row,column or cell.
Two such rcc9s are called disjoint , if all their 18 queens are
on different squares.
A solved NPP (number place puzzle) is nothing but a set of 9 mutually
Now I wrote a program that tried to generate solved NPPs in 9 steps:
On each step s :
count the number n(s) of rcc9s that are disjoint to all the other
previously selected rcc9s ,
and select one of those disjoint rcc9s at random.
some typical outcomes for the n(s) were:
Now I multiplied the n(s) , divided by 9! since the order doesn't
matter and got 1.5*10^16 in average.
Yes this was in 1998 , "rcc9s" = "templates", and he certainly understood.
Maybe this was refered to indirectly in the early days....
is reading this....