> < ^ From:

^ Subject:

Dear GAP Forum members,

On Feb. 22. Aaron Mackey asked:

I would be grateful for any references or pointers regarding the

enumeration algorithm used by NrArrangements.

I apologize that it has taken until now to contact Martin Schoenert

who had written that function, but anyhow here is his reply:

The algorithm is indeed rather straightforward. Basically the same

algorithm is used to compute the number of combinations, except that

NrCombinations does not take ordering into account. Of course this

algorithm is only used for arrangments of multi-sets. The number of

arrangments of a proper set uses a well known closed formula.

A description of the algorithm can be found in

>Concrete Mathematics: A Foundation For Computer Science

> Ronald L. Graham, Donald E. Knuth, Oren PatashnikMartin Schoenert

Joachim Neubueser

> < [top]