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NAME

       Gfan - program for computing with Groebner fans

DESCRIPTION

       This  is  a  program  for  computing all reduced Groebner bases of a polynomial ideal. It takes a generating set for the ideal as input. By
       default the enumeration is done by an almost memoryless reverse search. If the ideal is symmetric the symmetry option is useful and enumer-
       ation  will be done up to symmetry using a breadth first search. The program needs a starting Groebner basis to do its computations. If the
       -g option is not specified it will compute one using Buchberger's algorithm.

       Usage:

	      /usr/bin/gfan [options]

       Options:

       -g     Tells the program that the input is already a Groebner basis (with the initial term of each polynomial being the first ones listed).
	      Use  this  option  if it takes too much time to compute the starting (standard degree lexicographic) Groebner basis and the input is
	      already a Groebner basis.

       --symmetry
	       Tells the program to read in generators for a group of symmetries (subgroup of $S_n$) after having read in the ideal.  The  program
	      checks that the ideal stays fixed when permuting the variables with respect to elements in the group. The program uses breadth first
	      search to compute the set of reduced Groebner bases up to symmetry with respect to the specified subgroup.

       -e     Echo. Output the generators for the symmetry group.

       --subspace
	      Only do breadth first search on cones with their interior intersecting a specified subspace. The subspace is  given  by  a  list	of
	      hyperplane  normals  at the end of the input. The intersection of the hyperplanes is the subspace being specified. Note that the set
	      of Groebner cones intersecting the subspace could be disconnected and that only one connected  component	is  computed.  Works  only
	      together with --symmetry.

       --disableSymmetryTest
	      When  using  --symmetry  this option will disable the check that the group read off from the input actually is a symmetry group with
	      respect to the input ideal.

Gfan Groebner fan package   Version 0.3 			     May 2008								   GFAN(1)