From: Stephan Kepser
Subject: Partitioning a set
Date: 
Message-ID: <3n8npv$hid@sunserver.lrz-muenchen.de>
Hello!

I'm faced with the problem to calculate all possible partitionings of a  
given set. This sounds like quite a general problem to me, so someone may  
have solved it already.

It is not too difficult to write a function that computes and outputs all  
partitionings all at once. Now, because the number of partitionings is  
incredibly large even for small sets (an 8 elements set has 4140 different  
paritionings!), this approach becomes quickly untractable. Thus the task  
is to write a function that computes the partitionings incrementally. By  
that I mean a function which computes the partitionings one by one.  
Starting with the first, the function calcultates the next partitioning  
given the current one as input WITHOUT explicit storing which  
partitionings have already been calculated.

I hope someone solved this problem already or has otherwise useful hints.

Stephan.
--
Stephan Kepser           ······@cis.uni-muenchen.de
CIS   Centrum fuer Informations- und Sprachverarbeitung
LMU Muenchen, Wagmuellerstr. 23/III, D-80538 Muenchen,  Germany
Tel: +49 +89/2110666     Fax: +49 +89/2110674