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Some more work.

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This commit is contained in:
chriseth 2022-04-02 15:46:43 +02:00
parent c3583a7b01
commit aebe9753ff
2 changed files with 89 additions and 13 deletions
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99
libsolutil/LP.cpp
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@ -606,7 +606,7 @@ string SolvingState::toString() const
SimplexWithBounds::SimplexWithBounds(SolvingState _state):
m_state(move(_state))
{
size_t varsNeeded = m_state.constraints.size();
size_t varsNeeded = m_state.constraints.size();
size_t row = 0;
// TODO the new method does not need zero as lower-bound on all variables,
// but we currently assume that in the BooleanLP at some places.
@ -616,6 +616,7 @@ SimplexWithBounds::SimplexWithBounds(SolvingState _state):
for (Constraint& c: m_state.constraints)
{
// TODO duplicated in addConstraint
c.data.resize(m_state.variableNames.size() + varsNeeded);
size_t newVarIndex = m_state.variableNames.size();
m_basicVariables[newVarIndex] = row++;
@ -633,13 +634,15 @@ SimplexWithBounds::SimplexWithBounds(SolvingState _state):
}
m_assignments.resize(m_state.variableNames.size());
solAssert(m_assignments.size() == m_state.bounds.size());
}
LPResult SimplexWithBounds::check()
{
// cout << "===========================" << endl;
// cout << "===========================" << endl;
// cout << "simpl with bounds on\n" << toString() << endl;
solAssert(m_assignments.size() == m_state.bounds.size());
cout << "===========================" << endl;
cout << "===========================" << endl;
cout << "simpl with bounds on\n" << toString() << endl;
// We start with an all-zero assignment and then gradually add
// the bounds we already have.
@ -693,6 +696,40 @@ LPResult SimplexWithBounds::check()
}
size_t SimplexWithBounds::addVariable(string _name)
{
m_state.variableNames.emplace_back(move(_name));
m_state.bounds.emplace_back();
solAssert(m_state.variableNames.size() == m_state.bounds.size());
// TODO relax in the future.
m_state.bounds.back().lower = 0;
m_assignments.emplace_back(0);
size_t varsBefore = m_state.variableNames.size();
normalizeRowLengths(m_state);
solAssert(m_state.variableNames.size() == varsBefore);
m_assignments.resize(m_state.variableNames.size());
solAssert(m_assignments.size() == m_state.bounds.size());
return m_state.variableNames.size() - 1;
}
void SimplexWithBounds::addConstraint(Constraint _constraint)
{
m_state.constraints.emplace_back(move(_constraint));
Constraint& c = m_state.constraints.back();
// TODO name needed unique?
size_t slack = addVariable("_s" + to_string(m_state.variableNames.size()));
c.data.resize(m_state.variableNames.size());
m_basicVariables[slack] = m_state.constraints.size() - 1;
if (c.equality)
m_state.bounds.at(slack).lower = c.data[0];
m_state.bounds.at(slack).upper = c.data[0];
c.equality = true;
solAssert(c.data.size() > slack);
c.data[slack] = -1;
c.data[0] = 0;
solAssert(m_assignments.size() == m_state.bounds.size());
}
void SimplexWithBounds::update(size_t _var, rational const& _value)
{
rational delta = _value - m_assignments[_var];
@ -1100,6 +1137,10 @@ pair<LPResult, variant<Model, ReasonSet>> LPSolver::check()
auto&& [state, varMapping] = stateFromSubProblem(index);
problem->varMapping = move(varMapping);
// TODO if we do not use simplify, but just iteratively add constraints and bounsd
// to the simplex, we can detect "direct constraints" while adding (and compressing).
// and we might also be able to remove fixed variables.
// The simplify run is important because it detects conflicts
// due to fixed variables.
auto&& [result, modelOrReasonSet] = SolvingStateSimplifier{state}.simplify();
@ -1117,6 +1158,7 @@ pair<LPResult, variant<Model, ReasonSet>> LPSolver::check()
state.bounds.at(fixedVar).upper = value;
}
normalizeRowLengths(state);
problem->simplex = SimplexWithBounds{state};
}
@ -1232,16 +1274,47 @@ void LPSolver::addConstraintToSubProblem(size_t _subProblem, Constraint _constra
m_subProblems[_subProblem] = make_shared<SubProblem>(*m_subProblems[_subProblem]);
SubProblem& problem = *m_subProblems[_subProblem];
problem.dirty = true;
problem.simplex = nullopt;
for (auto const& [index, entry]: _constraint.data.enumerateTail())
if (entry)
{
solAssert(m_subProblemsPerVariable[index] == static_cast<size_t>(-1) || m_subProblemsPerVariable[index] == _subProblem);
m_subProblemsPerVariable[index] = _subProblem;
problem.variables.emplace(index);
}
if (problem.simplex)
{
Constraint compressedConstraint(_constraint);
compressedConstraint.data.resize(1, _constraint.data[0]);
for (auto const& [index, entry]: _constraint.data.enumerateTail())
if (entry)
{
size_t cIndex = 0;
if (problem.varMapping.count(index))
{
cIndex = problem.varMapping.at(index);
solAssert(m_subProblemsPerVariable.at(index) == _subProblem);
}
else
{
cIndex = problem.simplex->addVariable(m_state->variableNames.at(index));
problem.varMapping[index] = cIndex;
problem.variables.emplace(index);
solAssert(m_subProblemsPerVariable.at(index) == static_cast<size_t>(-1));
m_subProblemsPerVariable[index] = _subProblem;
}
solAssert(cIndex >= compressedConstraint.data.size());
compressedConstraint.data.resize(cIndex + 1);
compressedConstraint.data[cIndex] = entry;
}
problem.simplex->addConstraint(move(compressedConstraint));
}
else
{
problem.simplex = nullopt;
problem.varMapping = {};
for (auto const& [index, entry]: _constraint.data.enumerateTail())
if (entry)
{
solAssert(m_subProblemsPerVariable[index] == static_cast<size_t>(-1) || m_subProblemsPerVariable[index] == _subProblem);
m_subProblemsPerVariable[index] = _subProblem;
problem.variables.emplace(index);
}
}
// TODO if we keep the matrix, we could just add this as a new row.
problem.removableConstraints.emplace_back(move(_constraint));
}

3
libsolutil/LP.h
View File

@ -178,6 +178,9 @@ public:
explicit SimplexWithBounds(SolvingState _state);
LPResult check();
size_t addVariable(std::string _name);
void addConstraint(Constraint _constraint);
std::string toString() const;
private:
/// Set value of non-basic variable.