#  Copyright (c) 1997-2018
#  Ewgenij Gawrilow, Michael Joswig (Technische Universitaet Berlin, Germany)
#  http://www.polymake.org
#
#  This program is free software; you can redistribute it and/or modify it
#  under the terms of the GNU General Public License as published by the
#  Free Software Foundation; either version 2, or (at your option) any
#  later version: http://www.gnu.org/licenses/gpl.txt.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPSE.  See the
#  GNU General Public License for more details.
#-------------------------------------------------------------------------------

REQUIRE graph::compare.rules

object Matroid {

    rule AUTOMORPHISM_GROUP.PERMUTATION_ACTION(new).DEGREE, AUTOMORPHISM_GROUP.PERMUTATION_ACTION(new).GENERATORS : BASES, N_ELEMENTS {
        # Make sure the IncidenceMatrix has the right number of cols
        my $total_matrix = new IncidenceMatrix(@{$this->BASES}, $this->N_ELEMENTS);
        my @gens = map { $_->second } @{automorphisms($total_matrix)};
        if (@gens == 0) {
           # The identity is not returned by automorphisms
           push @gens, [0 .. $this->N_ELEMENTS-1];
        }

        $this->AUTOMORPHISM_GROUP->PERMUTATION_ACTION->DEGREE = $this->N_ELEMENTS;
        $this->AUTOMORPHISM_GROUP->PERMUTATION_ACTION->GENERATORS = \@gens;
        $this->AUTOMORPHISM_GROUP->PERMUTATION_ACTION->description = "permutation action of automorphism group";
        $this->AUTOMORPHISM_GROUP->description = "Automorphism group of ".$this->name if $this->name;
        $this->AUTOMORPHISM_GROUP->name = "Aut";
    }
    weight 5.10;
}

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