diff --git a/cartographer/pose_graph/constraint/acceleration_constraint_3d.cc b/cartographer/pose_graph/constraint/acceleration_constraint_3d.cc
index b0b36ab..87fbf6a 100644
--- a/cartographer/pose_graph/constraint/acceleration_constraint_3d.cc
+++ b/cartographer/pose_graph/constraint/acceleration_constraint_3d.cc
@@ -34,8 +34,8 @@ AccelerationConstraint3D::AccelerationConstraint3D(
       cost_(new AccelerationCost3D(proto.parameters())),
       ceres_cost_(absl::make_unique<AutoDiffFunction>(cost_)) {}
 
-void AccelerationConstraint3D::AddToOptimizer(Nodes* nodes,
-                                              ceres::Problem* problem) const {
+void AccelerationConstraint3D::AddToSolver(Nodes* nodes,
+                                           ceres::Problem* problem) const {
   FIND_NODE_OR_RETURN(first_node, first_, nodes->pose_3d_nodes,
                       "First node was not found in pose_3d_nodes.");
   FIND_NODE_OR_RETURN(second_node, second_, nodes->pose_3d_nodes,
diff --git a/cartographer/pose_graph/constraint/acceleration_constraint_3d.h b/cartographer/pose_graph/constraint/acceleration_constraint_3d.h
index 97c5b82..0321a83 100644
--- a/cartographer/pose_graph/constraint/acceleration_constraint_3d.h
+++ b/cartographer/pose_graph/constraint/acceleration_constraint_3d.h
@@ -29,7 +29,7 @@ class AccelerationConstraint3D : public Constraint {
                            const proto::LossFunction& loss_function_proto,
                            const proto::Acceleration3D& proto);
 
-  void AddToOptimizer(Nodes* nodes, ceres::Problem* problem) const final;
+  void AddToSolver(Nodes* nodes, ceres::Problem* problem) const final;
 
  protected:
   proto::CostFunction ToCostFunctionProto() const final;
diff --git a/cartographer/pose_graph/constraint/constraint.h b/cartographer/pose_graph/constraint/constraint.h
index cbbebb4..0fcda85 100644
--- a/cartographer/pose_graph/constraint/constraint.h
+++ b/cartographer/pose_graph/constraint/constraint.h
@@ -43,7 +43,7 @@ class Constraint {
 
   const ConstraintId& constraint_id() const { return constraint_id_; }
 
-  virtual void AddToOptimizer(Nodes* nodes, ceres::Problem* problem) const = 0;
+  virtual void AddToSolver(Nodes* nodes, ceres::Problem* problem) const = 0;
 
  protected:
   virtual proto::CostFunction ToCostFunctionProto() const = 0;
diff --git a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.cc b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.cc
index 0f30b15..7e8154b 100644
--- a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.cc
+++ b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.cc
@@ -33,7 +33,7 @@ InterpolatedRelativePoseConstraint2D::InterpolatedRelativePoseConstraint2D(
       cost_(new InterpolatedRelativePoseCost2D(proto.parameters())),
       ceres_cost_(absl::make_unique<AutoDiffFunction>(cost_)) {}
 
-void InterpolatedRelativePoseConstraint2D::AddToOptimizer(
+void InterpolatedRelativePoseConstraint2D::AddToSolver(
     Nodes* nodes, ceres::Problem* problem) const {
   FIND_NODE_OR_RETURN(first_node_start, first_start_, nodes->pose_2d_nodes,
                       "First node (start) was not found in pose_2d_nodes.");
diff --git a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.h b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.h
index 1260733..5635334 100644
--- a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.h
+++ b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_2d.h
@@ -29,7 +29,7 @@ class InterpolatedRelativePoseConstraint2D : public Constraint {
       const ConstraintId& id, const proto::LossFunction& loss_function_proto,
       const proto::InterpolatedRelativePose2D& proto);
 
-  void AddToOptimizer(Nodes* nodes, ceres::Problem* problem) const final;
+  void AddToSolver(Nodes* nodes, ceres::Problem* problem) const final;
 
  protected:
   proto::CostFunction ToCostFunctionProto() const final;
diff --git a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.cc b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.cc
index dc3f63e..73f31fa 100644
--- a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.cc
+++ b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.cc
@@ -33,7 +33,7 @@ InterpolatedRelativePoseConstraint3D::InterpolatedRelativePoseConstraint3D(
       cost_(new InterpolatedRelativePoseCost3D(proto.parameters())),
       ceres_cost_(absl::make_unique<AutoDiffFunction>(cost_)) {}
 
-void InterpolatedRelativePoseConstraint3D::AddToOptimizer(
+void InterpolatedRelativePoseConstraint3D::AddToSolver(
     Nodes* nodes, ceres::Problem* problem) const {
   FIND_NODE_OR_RETURN(first_node_start, first_start_, nodes->pose_3d_nodes,
                       "First node (start) was not found in pose_3d_nodes.");
diff --git a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.h b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.h
index 86c35b9..d836561 100644
--- a/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.h
+++ b/cartographer/pose_graph/constraint/interpolated_relative_pose_constraint_3d.h
@@ -29,7 +29,7 @@ class InterpolatedRelativePoseConstraint3D : public Constraint {
       const ConstraintId& id, const proto::LossFunction& loss_function_proto,
       const proto::InterpolatedRelativePose3D& proto);
 
-  void AddToOptimizer(Nodes* nodes, ceres::Problem* problem) const final;
+  void AddToSolver(Nodes* nodes, ceres::Problem* problem) const final;
 
  protected:
   proto::CostFunction ToCostFunctionProto() const final;
diff --git a/cartographer/pose_graph/constraint/relative_pose_constraint_2d.cc b/cartographer/pose_graph/constraint/relative_pose_constraint_2d.cc
index 9b7faa6..46f8264 100644
--- a/cartographer/pose_graph/constraint/relative_pose_constraint_2d.cc
+++ b/cartographer/pose_graph/constraint/relative_pose_constraint_2d.cc
@@ -32,8 +32,8 @@ RelativePoseConstraint2D::RelativePoseConstraint2D(
       ceres_cost_(absl::make_unique<RelativePoseCost2D>(proto.parameters())) {}
 
 // TODO(pifon): Add a test.
-void RelativePoseConstraint2D::AddToOptimizer(Nodes* nodes,
-                                              ceres::Problem* problem) const {
+void RelativePoseConstraint2D::AddToSolver(Nodes* nodes,
+                                           ceres::Problem* problem) const {
   FIND_NODE_OR_RETURN(first_node, first_, nodes->pose_2d_nodes,
                       "First node was not found in pose_2d_nodes.");
   FIND_NODE_OR_RETURN(second_node, second_, nodes->pose_2d_nodes,
diff --git a/cartographer/pose_graph/constraint/relative_pose_constraint_2d.h b/cartographer/pose_graph/constraint/relative_pose_constraint_2d.h
index dc76a6a..23c0bff 100644
--- a/cartographer/pose_graph/constraint/relative_pose_constraint_2d.h
+++ b/cartographer/pose_graph/constraint/relative_pose_constraint_2d.h
@@ -29,7 +29,7 @@ class RelativePoseConstraint2D : public Constraint {
                            const proto::LossFunction& loss_function_proto,
                            const proto::RelativePose2D& proto);
 
-  void AddToOptimizer(Nodes* nodes, ceres::Problem* problem) const final;
+  void AddToSolver(Nodes* nodes, ceres::Problem* problem) const final;
 
  protected:
   proto::CostFunction ToCostFunctionProto() const final;
diff --git a/cartographer/pose_graph/constraint/relative_pose_constraint_3d.cc b/cartographer/pose_graph/constraint/relative_pose_constraint_3d.cc
index dc19b8b..e688118 100644
--- a/cartographer/pose_graph/constraint/relative_pose_constraint_3d.cc
+++ b/cartographer/pose_graph/constraint/relative_pose_constraint_3d.cc
@@ -32,8 +32,8 @@ RelativePoseConstraint3D::RelativePoseConstraint3D(
       cost_(new RelativePoseCost3D(proto.parameters())),
       ceres_cost_(absl::make_unique<AutoDiffFunction>(cost_)) {}
 
-void RelativePoseConstraint3D::AddToOptimizer(Nodes* nodes,
-                                              ceres::Problem* problem) const {
+void RelativePoseConstraint3D::AddToSolver(Nodes* nodes,
+                                           ceres::Problem* problem) const {
   FIND_NODE_OR_RETURN(first_node, first_, nodes->pose_3d_nodes,
                       "First node was not found in pose_3d_nodes.");
   FIND_NODE_OR_RETURN(second_node, second_, nodes->pose_3d_nodes,
diff --git a/cartographer/pose_graph/constraint/relative_pose_constraint_3d.h b/cartographer/pose_graph/constraint/relative_pose_constraint_3d.h
index f6950cd..aadc066 100644
--- a/cartographer/pose_graph/constraint/relative_pose_constraint_3d.h
+++ b/cartographer/pose_graph/constraint/relative_pose_constraint_3d.h
@@ -29,7 +29,7 @@ class RelativePoseConstraint3D : public Constraint {
                            const proto::LossFunction& loss_function_proto,
                            const proto::RelativePose3D& proto);
 
-  void AddToOptimizer(Nodes* nodes, ceres::Problem* problem) const final;
+  void AddToSolver(Nodes* nodes, ceres::Problem* problem) const final;
 
  protected:
   proto::CostFunction ToCostFunctionProto() const final;
diff --git a/cartographer/pose_graph/constraint/rotation_constraint_3d.cc b/cartographer/pose_graph/constraint/rotation_constraint_3d.cc
index f1ed3db..b9bf6ee 100644
--- a/cartographer/pose_graph/constraint/rotation_constraint_3d.cc
+++ b/cartographer/pose_graph/constraint/rotation_constraint_3d.cc
@@ -53,8 +53,8 @@ RotationContraint3D::RotationContraint3D(
       cost_(new RotationCost3D(proto.parameters())),
       ceres_cost_(absl::make_unique<AutoDiffFunction>(cost_)) {}
 
-void RotationContraint3D::AddToOptimizer(Nodes* nodes,
-                                         ceres::Problem* problem) const {
+void RotationContraint3D::AddToSolver(Nodes* nodes,
+                                      ceres::Problem* problem) const {
   FIND_NODE_OR_RETURN(first_node, first_, nodes->pose_3d_nodes,
                       "First node was not found in pose_3d_nodes.");
   FIND_NODE_OR_RETURN(second_node, second_, nodes->pose_3d_nodes,
diff --git a/cartographer/pose_graph/constraint/rotation_constraint_3d.h b/cartographer/pose_graph/constraint/rotation_constraint_3d.h
index f681496..b0dbe24 100644
--- a/cartographer/pose_graph/constraint/rotation_constraint_3d.h
+++ b/cartographer/pose_graph/constraint/rotation_constraint_3d.h
@@ -29,7 +29,7 @@ class RotationContraint3D : public Constraint {
                       const proto::LossFunction& loss_function_proto,
                       const proto::Rotation3D& proto);
 
-  void AddToOptimizer(Nodes* nodes, ceres::Problem* problem) const final;
+  void AddToSolver(Nodes* nodes, ceres::Problem* problem) const final;
 
  protected:
   proto::CostFunction ToCostFunctionProto() const final;
diff --git a/cartographer/pose_graph/pose_graph_controller.cc b/cartographer/pose_graph/pose_graph_controller.cc
index b79b48c..bdd56d9 100644
--- a/cartographer/pose_graph/pose_graph_controller.cc
+++ b/cartographer/pose_graph/pose_graph_controller.cc
@@ -29,9 +29,9 @@ void PoseGraphController::AddConstraint(const proto::Constraint& constraint) {
   AddConstraintToPoseGraphData(constraint, &data_);
 }
 
-Optimizer::SolverStatus PoseGraphController::Optimize() {
+Solver::SolverStatus PoseGraphController::Optimize() {
   absl::MutexLock locker(&mutex_);
-  return optimizer_->Solve(&data_);
+  return solver_->Solve(&data_);
 }
 
 }  // namespace pose_graph
diff --git a/cartographer/pose_graph/pose_graph_controller.h b/cartographer/pose_graph/pose_graph_controller.h
index fd18896..33359da 100644
--- a/cartographer/pose_graph/pose_graph_controller.h
+++ b/cartographer/pose_graph/pose_graph_controller.h
@@ -18,15 +18,15 @@
 #define CARTOGRAPHER_POSE_GRAPH_POSE_GRAPH_CONTROLLER_H_
 
 #include "absl/synchronization/mutex.h"
-#include "cartographer/pose_graph/optimizer/optimizer.h"
 #include "cartographer/pose_graph/pose_graph_data.h"
+#include "cartographer/pose_graph/solver/solver.h"
 
 namespace cartographer {
 namespace pose_graph {
 
 class PoseGraphController {
-  PoseGraphController(std::unique_ptr<Optimizer> optimizer)
-      : optimizer_(std::move(optimizer)) {}
+  PoseGraphController(std::unique_ptr<Solver> optimizer)
+      : solver_(std::move(optimizer)) {}
 
   PoseGraphController(const PoseGraphController&) = delete;
   PoseGraphController& operator=(const PoseGraphController&) = delete;
@@ -35,10 +35,10 @@ class PoseGraphController {
   void AddConstraint(const proto::Constraint& constraint)
       LOCKS_EXCLUDED(mutex_);
 
-  Optimizer::SolverStatus Optimize() LOCKS_EXCLUDED(mutex_);
+  Solver::SolverStatus Optimize() LOCKS_EXCLUDED(mutex_);
 
  private:
-  std::unique_ptr<Optimizer> optimizer_;
+  std::unique_ptr<Solver> solver_;
 
   mutable absl::Mutex mutex_;
   PoseGraphData data_ GUARDED_BY(mutex_);
diff --git a/cartographer/pose_graph/optimizer/ceres_optimizer.cc b/cartographer/pose_graph/solver/ceres_solver.cc
similarity index 78%
rename from cartographer/pose_graph/optimizer/ceres_optimizer.cc
rename to cartographer/pose_graph/solver/ceres_solver.cc
index d08347d..3a7421b 100644
--- a/cartographer/pose_graph/optimizer/ceres_optimizer.cc
+++ b/cartographer/pose_graph/solver/ceres_solver.cc
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#include "cartographer/pose_graph/optimizer/ceres_optimizer.h"
+#include "cartographer/pose_graph/solver/ceres_solver.h"
 
 namespace cartographer {
 namespace pose_graph {
@@ -31,28 +31,28 @@ ceres::Problem::Options CreateCeresProblemOptions() {
   return problem_options;
 }
 
-Optimizer::SolverStatus ToSolverStatus(
+Solver::SolverStatus ToSolverStatus(
     const ceres::TerminationType& termination_type) {
   switch (termination_type) {
     case (ceres::TerminationType::CONVERGENCE):
-      return Optimizer::SolverStatus::CONVERGENCE;
+      return Solver::SolverStatus::CONVERGENCE;
     case (ceres::TerminationType::NO_CONVERGENCE):
-      return Optimizer::SolverStatus::NO_CONVERGENCE;
+      return Solver::SolverStatus::NO_CONVERGENCE;
     default:
-      return Optimizer::SolverStatus::FAILURE;
+      return Solver::SolverStatus::FAILURE;
   }
 }
 
 }  // namespace
 
-CeresOptimizer::CeresOptimizer(const ceres::Solver::Options& options)
+CeresSolver::CeresSolver(const ceres::Solver::Options& options)
     : problem_options_(CreateCeresProblemOptions()), solver_options_(options) {}
 
-Optimizer::SolverStatus CeresOptimizer::Solve(PoseGraphData* data) const {
+Solver::SolverStatus CeresSolver::Solve(PoseGraphData* data) const {
   ceres::Problem problem(problem_options_);
 
   for (const auto& constraint : data->constraints) {
-    constraint->AddToOptimizer(&data->nodes, &problem);
+    constraint->AddToSolver(&data->nodes, &problem);
   }
 
   ceres::Solver::Summary summary;
diff --git a/cartographer/pose_graph/optimizer/ceres_optimizer.h b/cartographer/pose_graph/solver/ceres_solver.h
similarity index 73%
rename from cartographer/pose_graph/optimizer/ceres_optimizer.h
rename to cartographer/pose_graph/solver/ceres_solver.h
index 3689ff3..fcaa365 100644
--- a/cartographer/pose_graph/optimizer/ceres_optimizer.h
+++ b/cartographer/pose_graph/solver/ceres_solver.h
@@ -14,19 +14,19 @@
  * limitations under the License.
  */
 
-#ifndef CARTOGRAPHER_POSE_GRAPH_OPTIMIZER_CERES_OPTIMIZER_H_
-#define CARTOGRAPHER_POSE_GRAPH_OPTIMIZER_CERES_OPTIMIZER_H_
+#ifndef CARTOGRAPHER_POSE_GRAPH_OPTIMIZER_CERES_SOLVER_H_
+#define CARTOGRAPHER_POSE_GRAPH_OPTIMIZER_CERES_SOLVER_H_
 
-#include "cartographer/pose_graph/optimizer/optimizer.h"
+#include "cartographer/pose_graph/solver/solver.h"
 #include "ceres/problem.h"
 #include "ceres/solver.h"
 
 namespace cartographer {
 namespace pose_graph {
 
-class CeresOptimizer : public Optimizer {
+class CeresSolver : public Solver {
  public:
-  explicit CeresOptimizer(const ceres::Solver::Options& options);
+  explicit CeresSolver(const ceres::Solver::Options& options);
 
   SolverStatus Solve(PoseGraphData* data) const final;
 
@@ -38,4 +38,4 @@ class CeresOptimizer : public Optimizer {
 }  // namespace pose_graph
 }  // namespace cartographer
 
-#endif  // CARTOGRAPHER_POSE_GRAPH_OPTIMIZER_CERES_OPTIMIZER_H_
+#endif  // CARTOGRAPHER_POSE_GRAPH_OPTIMIZER_CERES_SOLVER_H_
diff --git a/cartographer/pose_graph/optimizer/ceres_optimizer_test.cc b/cartographer/pose_graph/solver/ceres_solver_test.cc
similarity index 89%
rename from cartographer/pose_graph/optimizer/ceres_optimizer_test.cc
rename to cartographer/pose_graph/solver/ceres_solver_test.cc
index d4ab8e4..f86b9ae 100644
--- a/cartographer/pose_graph/optimizer/ceres_optimizer_test.cc
+++ b/cartographer/pose_graph/solver/ceres_solver_test.cc
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#include "cartographer/pose_graph/optimizer/ceres_optimizer.h"
+#include "cartographer/pose_graph/solver/ceres_solver.h"
 
 #include "absl/memory/memory.h"
 #include "cartographer/pose_graph/constraint/relative_pose_constraint_2d.h"
@@ -67,14 +67,14 @@ constexpr char kRelativePose2D[] = R"PROTO(
   }
 )PROTO";
 
-TEST(CeresOptimizerTest, SmokeTest) {
+TEST(CeresSolverTest, SmokeTest) {
   PoseGraphData data;
   AddNodeToPoseGraphData(ParseProto<proto::Node>(kStartNode), &data);
   AddNodeToPoseGraphData(ParseProto<proto::Node>(kEndNode), &data);
   AddConstraintToPoseGraphData(ParseProto<proto::Constraint>(kRelativePose2D),
                                &data);
-  CeresOptimizer optimizer(ceres::Solver::Options{});
-  EXPECT_EQ(optimizer.Solve(&data), Optimizer::SolverStatus::CONVERGENCE);
+  CeresSolver optimizer(ceres::Solver::Options{});
+  EXPECT_EQ(optimizer.Solve(&data), Solver::SolverStatus::CONVERGENCE);
 }
 
 }  // namespace
diff --git a/cartographer/pose_graph/optimizer/optimizer.h b/cartographer/pose_graph/solver/solver.h
similarity index 73%
rename from cartographer/pose_graph/optimizer/optimizer.h
rename to cartographer/pose_graph/solver/solver.h
index c6aa062..11bb2a1 100644
--- a/cartographer/pose_graph/optimizer/optimizer.h
+++ b/cartographer/pose_graph/solver/solver.h
@@ -14,15 +14,15 @@
  * limitations under the License.
  */
 
-#ifndef CARTOGRAPHER_POSE_GRAPH_OPTIMIZER_OPTIMIZER_H_
-#define CARTOGRAPHER_POSE_GRAPH_OPTIMIZER_OPTIMIZER_H_
+#ifndef CARTOGRAPHER_POSE_GRAPH_SOLVER_SOLVER_H_
+#define CARTOGRAPHER_POSE_GRAPH_SOLVER_SOLVER_H_
 
 #include "cartographer/pose_graph/pose_graph_data.h"
 
 namespace cartographer {
 namespace pose_graph {
 
-class Optimizer {
+class Solver {
  public:
   enum class SolverStatus {
     CONVERGENCE,
@@ -30,11 +30,11 @@ class Optimizer {
     FAILURE,
   };
 
-  Optimizer() = default;
-  virtual ~Optimizer() = default;
+  Solver() = default;
+  virtual ~Solver() = default;
 
-  Optimizer(const Optimizer&) = delete;
-  Optimizer& operator=(const Optimizer&) = delete;
+  Solver(const Solver&) = delete;
+  Solver& operator=(const Solver&) = delete;
 
   virtual SolverStatus Solve(PoseGraphData* data) const = 0;
 };
@@ -42,4 +42,4 @@ class Optimizer {
 }  // namespace pose_graph
 }  // namespace cartographer
 
-#endif  // CARTOGRAPHER_POSE_GRAPH_OPTIMIZER_OPTIMIZER_H_
+#endif  // CARTOGRAPHER_POSE_GRAPH_SOLVER_SOLVER_H_