91 lines
2.9 KiB
C++
91 lines
2.9 KiB
C++
// Copyright 2010-2022 Google LLC
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef OR_TOOLS_BOP_BOP_UTIL_H_
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#define OR_TOOLS_BOP_BOP_UTIL_H_
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#include <vector>
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#include "ortools/base/basictypes.h"
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#include "ortools/base/integral_types.h"
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#include "ortools/bop/bop_base.h"
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#include "ortools/bop/bop_solution.h"
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#include "ortools/sat/sat_solver.h"
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namespace operations_research {
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namespace bop {
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// Loads the problem state into the sat_solver. If the problem has already been
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// loaded in the sat_solver, fixed variables and objective bounds are updated.
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// Returns the status of the load:
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// - CONTINUE: State problem successfully loaded.
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// - OPTIMAL_SOLUTION_FOUND: Solution is proved optimal.
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// If a feasible solution exists, this load function imposes the solution
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// to be strictly better. Then when SAT proves the problem is UNSAT, that
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// actually means that the current solution is optimal.
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// - INFEASIBLE: The problem is proved to be infeasible.
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// Note that the sat_solver will be backtracked to the root level in order
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// to add new constraints.
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BopOptimizerBase::Status LoadStateProblemToSatSolver(
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const ProblemState& problem_state, sat::SatSolver* sat_solver);
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// Extracts from the sat solver any new information about the problem. Note that
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// the solver is not const because this function clears what is considered
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// "new".
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void ExtractLearnedInfoFromSatSolver(sat::SatSolver* solver, LearnedInfo* info);
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void SatAssignmentToBopSolution(const sat::VariablesAssignment& assignment,
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BopSolution* solution);
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class AdaptiveParameterValue {
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public:
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// Initial value is in [0..1].
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explicit AdaptiveParameterValue(double initial_value);
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void Reset();
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void Increase();
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void Decrease();
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double value() const { return value_; }
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private:
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double value_;
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int num_changes_;
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};
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class LubyAdaptiveParameterValue {
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public:
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// Initial value is in [0..1].
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explicit LubyAdaptiveParameterValue(double initial_value);
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void Reset();
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void IncreaseParameter();
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void DecreaseParameter();
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double GetParameterValue() const;
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void UpdateLuby();
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bool BoostLuby();
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int luby_value() const { return luby_value_; }
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private:
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int luby_id_;
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int luby_boost_;
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int luby_value_;
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std::vector<AdaptiveParameterValue> difficulties_;
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};
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} // namespace bop
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} // namespace operations_research
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#endif // OR_TOOLS_BOP_BOP_UTIL_H_
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