Francois Maltey <[EMAIL PROTECTED]> writes:
> > [matrix [[a,b,15-a-b],[c,d,15-c-d]] _
> > for (a,b,c,d) in CartesianProduct([1..9, 1..9, 1..9, 1..9])]
> But what is the signature of this function CartesianProduct ?
Sorry, I didn't bother to think about a good way to specify the Cartesian
product itself, but I think what Bill showed was quite good.
> The concat command :
>
> concat
> [concat [[[matrix [[a,b,15-a-b],[c,d,15-c-d]] for a in 1..9]
> for b in 1..9]
> for c in 1..9]
> for d in 1..9]
>
> builds Union_{for d} (Union_{for c} (Union_{for b} set of matrix for a)
> and isn't a mathematic translation of a cartesian product.
I believe it is:
Union_{c\in C} Union_{b\in B} Union_{a\in A} F_{a,b,c}
is the same as
Union_{(a,b,c)\in A x B x C} F_{a,b,c}
Martin
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