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/********************* */
/*! \file tableau.h
** \verbatim
** Top contributors (to current version):
** Tim King
** This file is part of the CVC4 project.
** Copyright (c) 2009-2018 by the authors listed in the file AUTHORS
** in the top-level source directory) and their institutional affiliations.
** All rights reserved. See the file COPYING in the top-level source
** directory for licensing information.\endverbatim
**
** \brief [[ Add one-line brief description here ]]
**
** [[ Add lengthier description here ]]
** \todo document this file
**/
#include "cvc4_private.h"
#pragma once
#include <vector>
#include "theory/arith/arithvar.h"
#include "theory/arith/matrix.h"
#include "util/dense_map.h"
#include "util/rational.h"
namespace CVC4 {
namespace theory {
namespace arith {
/**
* A Tableau is a Rational matrix that keeps its rows in solved form.
* Each row has a basic variable with coefficient -1 that is solved.
* Tableau is optimized for pivoting.
* The tableau should only be updated via pivot calls.
*/
class Tableau : public Matrix<Rational> {
public:
private:
typedef DenseMap<RowIndex> BasicToRowMap;
// Set of all of the basic variables in the tableau.
// ArithVarMap<RowIndex> : ArithVar |-> RowIndex
BasicToRowMap d_basic2RowIndex;
// RowIndex |-> Basic Variable
typedef DenseMap<ArithVar> RowIndexToBasicMap;
RowIndexToBasicMap d_rowIndex2basic;
public:
Tableau() : Matrix<Rational>(Rational(0)) {}
typedef Matrix<Rational>::ColIterator ColIterator;
typedef Matrix<Rational>::RowIterator RowIterator;
typedef BasicToRowMap::const_iterator BasicIterator;
typedef MatrixEntry<Rational> Entry;
bool isBasic(ArithVar v) const{
return d_basic2RowIndex.isKey(v);
}
void debugPrintIsBasic(ArithVar v) const {
if(isBasic(v)){
Warning() << v << " is basic." << std::endl;
}else{
Warning() << v << " is non-basic." << std::endl;
}
}
BasicIterator beginBasic() const {
return d_basic2RowIndex.begin();
}
BasicIterator endBasic() const {
return d_basic2RowIndex.end();
}
RowIndex basicToRowIndex(ArithVar x) const {
return d_basic2RowIndex[x];
}
ArithVar rowIndexToBasic(RowIndex rid) const {
Assert(d_rowIndex2basic.isKey(rid));
return d_rowIndex2basic[rid];
}
ColIterator colIterator(ArithVar x) const {
return getColumn(x).begin();
}
RowIterator ridRowIterator(RowIndex rid) const {
return getRow(rid).begin();
}
RowIterator basicRowIterator(ArithVar basic) const {
return ridRowIterator(basicToRowIndex(basic));
}
const Entry& basicFindEntry(ArithVar basic, ArithVar col) const {
return findEntry(basicToRowIndex(basic), col);
}
/**
* Adds a row to the tableau.
* The new row is equivalent to:
* basicVar = \f$\sum_i\f$ coeffs[i] * variables[i]
* preconditions:
* basicVar is already declared to be basic
* basicVar does not have a row associated with it in the tableau.
*
* Note: each variables[i] does not have to be non-basic.
* Pivoting will be mimicked if it is basic.
*/
void addRow(ArithVar basicVar,
const std::vector<Rational>& coeffs,
const std::vector<ArithVar>& variables);
/**
* preconditions:
* x_r is basic,
* x_s is non-basic, and
* a_rs != 0.
*/
void pivot(ArithVar basicOld, ArithVar basicNew, CoefficientChangeCallback& cb);
void removeBasicRow(ArithVar basic);
uint32_t basicRowLength(ArithVar basic) const{
RowIndex ridx = basicToRowIndex(basic);
return getRowLength(ridx);
}
/**
* to += mult * from
* replacing from with its row.
*/
void substitutePlusTimesConstant(ArithVar to, ArithVar from, const Rational& mult, CoefficientChangeCallback& cb);
void directlyAddToCoefficient(ArithVar rowVar, ArithVar col, const Rational& mult, CoefficientChangeCallback& cb){
RowIndex ridx = basicToRowIndex(rowVar);
manipulateRowEntry(ridx, col, mult, cb);
}
/* Returns the complexity of a row in the tableau. */
uint32_t rowComplexity(ArithVar basic) const;
/* Returns the average complexity of the rows in the tableau. */
double avgRowComplexity() const;
void printBasicRow(ArithVar basic, std::ostream& out);
private:
/* Changes the basic variable on the row for basicOld to basicNew. */
void rowPivot(ArithVar basicOld, ArithVar basicNew, CoefficientChangeCallback& cb);
};/* class Tableau */
}/* CVC4::theory::arith namespace */
}/* CVC4::theory namespace */
}/* CVC4 namespace */
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