Computing strongly connected components
Copyright (c) 2000  2003, Wolfgang Lux See LICENSE for the full license.
The function scc
computes the strongly connected components of a list
of entities in two steps. First, the list is topologically sorted
"downwards" using the defines
relation.
Then the resulting list is sorted "upwards" using the uses
relation
and partitioned into the connected components. Both relations
are computed within this module using the bound and free names of each
declaration.
In order to avoid useless recomputations, the code in the module first decorates the declarations with their bound and free names and a unique number. The latter is only used to provide a trivial ordering so that the declarations can be used as set elements.
Author: Wolfgang Lux
scc
:: (a > [b]) > (a > [b]) > [a] > [[a]]
Computes the strongly connected components of a list of entities. 
Computes the strongly connected components of a list of entities. To be flexible, we distinguish the nodes and the entities defined in this node.
