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/* Copyright (c) 1997-2024
Ewgenij Gawrilow, Michael Joswig, and the polymake team
Technische Universität Berlin, Germany
https://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 PURPOSE. See the
GNU General Public License for more details.
--------------------------------------------------------------------------------
*/
#pragma once
#include "polymake/Array.h"
#include "polymake/Set.h"
#include "polymake/PowerSet.h"
#include "polymake/graph/Lattice.h"
#include "polymake/graph/Decoration.h"
namespace polymake { namespace matroid {
Array<Set<Int>> bases_from_lof_impl(const graph::Lattice<graph::lattice::BasicDecoration, graph::lattice::Sequential>& LF, Int n)
{
const Int rank = LF.rank();
if (rank == 0) {
return Array<Set<Int>>(1);
}
std::vector<Set<Int>> bases;
for (auto bit = entire(all_subsets_of_k(sequence(0, n), rank)); !bit.at_end(); ++bit) {
const Set<Int> basis(*bit);
bool dependent = false;
for (Int k = rank-1; k >= 0; --k) {
for (auto fi = entire(LF.nodes_of_rank(k)); !dependent && !fi.at_end(); ++fi) {
if (incl(basis, LF.face(*fi)) <= 0)
dependent = true;
}
}
if (!dependent) bases.push_back(basis);
}
return Array<Set<Int>>(bases.size(), entire(bases));
}
} }
// Local Variables:
// mode:C++
// c-basic-offset:3
// indent-tabs-mode:nil
// End:
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