OR-Tools  8.2
cp_model_postsolve.h
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1// Copyright 2010-2018 Google LLC
2// Licensed under the Apache License, Version 2.0 (the "License");
3// you may not use this file except in compliance with the License.
4// You may obtain a copy of the License at
5//
6// http://www.apache.org/licenses/LICENSE-2.0
7//
8// Unless required by applicable law or agreed to in writing, software
9// distributed under the License is distributed on an "AS IS" BASIS,
10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11// See the License for the specific language governing permissions and
12// limitations under the License.
13
14#ifndef OR_TOOLS_SAT_CP_MODEL_POSTSOLVE_H_
15#define OR_TOOLS_SAT_CP_MODEL_POSTSOLVE_H_
16
17#include <vector>
18
20#include "ortools/sat/cp_model.pb.h"
21
22namespace operations_research {
23namespace sat {
24
25// Postsolves the given response using information filled by our presolver.
26//
27// This works as follow:
28// - First we fix fixed variables of the mapping_model according to the solution
29// of the presolved problem and the index mapping.
30// - Then, we process the mapping constraints in "reverse" order, and unit
31// propagate each of them when necessary. By construction this should never
32// give rise to any conflicts. And after each constraints, we should have
33// a feasible solution to the presolved problem + all already postsolved
34// constraints. This is the invariant we maintain.
35// - Finally, we arbitrarily fix any free variables left and update the given
36// response with the new solution.
37//
38// Note: Most of the postsolve operations require the constraints to have been
39// written in the correct way by the presolve.
40//
41// TODO(user): We could use the search strategy to fix free variables to some
42// chosen values? The feature might never be needed though.
43void PostsolveResponse(const int64 num_variables_in_original_model,
44 const CpModelProto& mapping_proto,
45 const std::vector<int>& postsolve_mapping,
46 CpSolverResponse* response);
47
48} // namespace sat
49} // namespace operations_research
50
51#endif // OR_TOOLS_SAT_CP_MODEL_POSTSOLVE_H_
SharedResponseManager * response
int64_t int64
void PostsolveResponse(const int64 num_variables_in_original_model, const CpModelProto &mapping_proto, const std::vector< int > &postsolve_mapping, CpSolverResponse *response)
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