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/*
Cadabra: a field-theory motivated computer algebra system.
Copyright (C) 2001-2014 Kasper Peeters <kasper.peeters@phi-sci.com>
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 3 of the
License, or (at your option) any later version.
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.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
Functions to handle the exchange properties of two or more symbols
in a product. This module is only concerned with the exchange
properties of tensors as a whole, not with index permutation symmetries
(which are handled in the canonicalise class of algebra.cc).
*/
#pragma once
#include <vector>
#include "Storage.hh"
#include "properties/GammaMatrix.hh"
#include "properties/Spinor.hh"
#include "properties/Traceless.hh"
#include "properties/GammaTraceless.hh"
#include "properties/SelfCommutingBehaviour.hh"
#include "properties/CommutingBehaviour.hh"
namespace cadabra {
class exchange {
public:
struct identical_tensors_t {
unsigned int number_of_indices;
std::vector<Ex::sibling_iterator> tensors;
std::vector<int> seq_numbers_of_first_indices;
const SelfCommutingBehaviour *comm;
const Spinor *spino;
const TableauBase *tab;
const Traceless *traceless;
const GammaTraceless *gammatraceless;
int extra_sign;
};
// Obtain index exchange symmetries under tensor permutation. Returns 'false' if
// an identically zero expression is encountered.
static int collect_identical_tensors(const Properties& pr, Ex& tr, Ex::iterator it,
std::vector<identical_tensors_t>& idts);
static unsigned int possible_singlets(Ex&, Ex::iterator);
static bool get_node_gs(const Properties&, Ex&, Ex::iterator, std::vector<std::vector<int> >& );
// static void get_index_gs(Ex::iterator, std::vector<std::vector<int> >& );
struct tensor_type_t {
nset_t::iterator name;
unsigned int number_of_indices;
};
};
bool operator<(const exchange::tensor_type_t& one, const exchange::tensor_type_t& two);
}
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