Newsgroups: comp.parallel
From: pelegrin@labri.u-bordeaux.fr (Francois PELLEGRINI)
Subject: ANNOUNCING : SCOTCH Static Mapping Package v3.0
Keywords: static mapping, graph bipartitioning
Organization: NASA Ames Res. Ctr. Mtn Vw CA 94035
Date: 18 Dec 1995 19:45:39 GMT
Message-ID: <4b4gd3$lo5@onramp.arc.nasa.gov>

		    SCOTCH: Static Mapping Package

			---------------------


      We announce the release of the SCOTCH software for static mapping.
		Release 3.0 is now available via WWW and ftp.


Application domains
===================

Static mapping has extensive applications  in many areas, including scienti-
fic computing, scheduling, and VLSI layout. The problem is to map the verti-
ces of  a source  graph onto the  vertices of  a target graph  such that the
weight of the source graph vertices is  balanced with respect to the weights
of the target graph  vertices, and such that some  communication function is
minimized. Static mapping is very  important for finite element computations
on parallel machines, since good mappings significantly increase the perfor-
mance by  reducing the  communication  overhead, particularly  long-distance
communication.


What is SCOTCH
==============

SCOTCH is a project carried out at the Laboratoire Bordelais de Recherche en
Informatique (LaBRI) of the Universite  Bordeaux I, by the ALiENor (parallel
ALgorithmics and ENvironments)  team. Its goal is to study static mapping by
the means  of graph  theory, using a ``divide  and conquer''  approach. This
work  has resulted in  the development of the Dual  Recursive Bipartitioning
(or DRB)  mapping algorithm and the analysis of several graph bipartitioning
heuristics.

The SCOTCH software  package for static mapping  embodies all the algorithms
and graph bipartitioning heuristics developed within the SCOTCH project. Its
principal features are:

-> SCOTCH can map any weighted source graph onto any weighted target graph.
   The source and  target graphs may  have any topology,  and their vertices
   and edges may be weighted. Moreover, both source and target graphs may be
   disconnected. This feature allows the mapping of programs onto disconnec-
   ted subparts of a parallel architecture made up of processors and commun-
   ication links of different nature.

-> SCOTCH provides high quality mappings.
   The mappings  computed by SCOTCH  are consistently  better than  the ones
   computed  by   Recursive  Spectral   Bissection  followed   by  refinment
   algorithms such as Cyclic Pairwise Exchange.
   The graph  partitions obtained when  mapping onto the  complete graph are
   equivalent in quality to the ones obtained with MeTiS and Chaco on a wide
   variety of graphs.

-> SCOTCH is fast.
   The running time of the SCOTCH mapper is linear in the number of edges of
   the source graph and logarithmic  in the number of vertices of the target
   graph. Multi-level graph  partitioning  routines should  further speed-up
   mapping computations, and will be available soon.

-> SCOTCH can be easily interfaced to other programs.
   The programs comprising  the SCOTCH project have been  designed to run in
   command-line mode without any  interactive prompting, so that they can be
   called  easily  from  other  programs   by  means  of  ``system  ()''  or
   ``popen ()'' calls, or piped together on a single command line.
   Moreover,  vertex labeling  capabilities allow  for  easy renumbering  of
   vertices.

-> SCOTCH offers many tools to build, check, and display graphs.


How to get SCOTCH
=================

The SCOTCH  academic distribution  may be  obtained via WWW  from the SCOTCH
page at
  http://www.labri.u-bordeaux.fr/~pelegrin/scotch/
or by anonymous ftp at
  ftp.u-bordeaux.fr
in directory
  /pub/Local/Info/Software/Scotch .
It is labeled
  scotch_3.0A.tar.gz .

Most of  the documentation  regarding  SCOTCH is  available by  WWW from the
aforementioned SCOTCH web page. Should you have any questions or problems on
obtaining SCOTCH, please send e-mail to
  pelegrin@labri.u-bordeaux.fr .



