Deformer.cpp
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/* Frobby: Software for monomial ideal computations.
Copyright (C) 2010 University of Aarhus
Contact Bjarke Hammersholt Roune for license information (www.broune.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 2 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/.
*/
#include "stdinc.h"
#include "Deformer.h"
#include "Term.h"
#include "TermPredicate.h"
#include "Ideal.h"
#include "TermPredicate.h"
#include "error.h"
#include "IdealOrderer.h"
#include <map>
namespace {
void deform(Ideal& ideal,
vector<Exponent>& undeform,
size_t var,
bool stronglyGeneric) {
ASSERT(undeform.empty());
map<Exponent, vector<Exponent*> > exps;
Ideal::const_iterator end = ideal.end();
for (Ideal::const_iterator it = ideal.begin(); it != end; ++it) {
Exponent& e = (*it)[var];
if (e == 0)
continue;
exps[e].push_back(*it);
}
Term tmp(ideal.getVarCount());
undeform.push_back(0); // zero always maps to zero
for (map<Exponent, vector<Exponent*> >::iterator it = exps.begin();
it != exps.end(); ++it) {
vector<Exponent*>& block = it->second;
typedef vector<Exponent*>::iterator BlockIt;
if (stronglyGeneric) {
for (BlockIt blockIt = block.begin(); blockIt != block.end();
++blockIt) {
undeform.push_back((*blockIt)[var]);
(*blockIt)[var] = undeform.size() - 1;
}
} else {
undeform.push_back(block.front()[var]);
Exponent sharedDeformedExponent = undeform.size() - 1;
for (BlockIt blockIt = block.begin(); blockIt != block.end();
++blockIt) {
bool canUseShared = true;
for (BlockIt other = blockIt + 1; other != block.end(); ++other) {
tmp.lcm(*blockIt, *other);
if (!ideal.strictlyContains(tmp)) {
canUseShared = false;
break;
}
}
if (canUseShared)
(*blockIt)[var] = sharedDeformedExponent;
else {
undeform.push_back((*blockIt)[var]);
(*blockIt)[var] = undeform.size() - 1;
}
}
}
}
}
}
Deformer::Deformer(Ideal& ideal,
const IdealOrderer& orderer,
bool stronglyGeneric):
_undeform(ideal.getVarCount()) {
orderer.order(ideal);
for (size_t var = 0; var < ideal.getVarCount(); ++var)
deform(ideal, _undeform[var], var, stronglyGeneric);
ASSERT(!stronglyGeneric || ideal.isStronglyGeneric());
ASSERT(ideal.isWeaklyGeneric());
}
void Deformer::undeform(Term& term) const {
ASSERT(term.getVarCount() == _undeform.size());
for (size_t var = 0; var < term.getVarCount(); ++var) {
ASSERT(term[var] < _undeform[var].size());
term[var] = _undeform[var][term[var]];
}
}
Deformer.h
IdealOrderer.h
Ideal.h
TermPredicate.h
Term.h
Deformer::Deformer
Deformer(Ideal &ideal, const IdealOrderer &deformationOrder, bool makeStronglyGeneric=true)
Apply a generic deformation to ideal such that it becomes generic.
Definition Deformer.cpp:85
Deformer::_undeform
vector< vector< Exponent > > _undeform
var^e undeforms to var^(_undeform[var][e]).
Definition Deformer.h:53
Deformer::undeform
void undeform(Term &term) const
Apply the reverse transformation on term than that applied to the Ideal passed to the constructor.
Definition Deformer.cpp:99
IdealOrderer
Definition IdealOrderer.h:23
IdealOrderer::order
void order(Ideal &ideal) const
Definition IdealOrderer.h:27
Ideal
Represents a monomial ideal with int exponents.
Definition Ideal.h:27
Ideal::const_iterator
Cont::const_iterator const_iterator
Definition Ideal.h:43
Ideal::strictlyContains
bool strictlyContains(const Exponent *term) const
Definition Ideal.cpp:73
Ideal::end
const_iterator end() const
Definition Ideal.h:49
Ideal::begin
const_iterator begin() const
Definition Ideal.h:48
Ideal::isWeaklyGeneric
bool isWeaklyGeneric() const
Definition Ideal.cpp:121
Ideal::isStronglyGeneric
bool isStronglyGeneric()
Definition Ideal.cpp:106
Ideal::getVarCount
size_t getVarCount() const
Definition Ideal.h:56
Term
Term represents a product of variables which does not include a coefficient.
Definition Term.h:49
Term::getVarCount
size_t getVarCount() const
Definition Term.h:85
error.h
stdinc.h
This header file includes common definitions and is included as the first line of code in every imple...
Exponent
unsigned int Exponent
Definition stdinc.h:89
ASSERT
#define ASSERT(X)
Definition stdinc.h:86