diff --git a/Solver_interface/doc/Solver_interface/Solver_interface.txt b/Solver_interface/doc/Solver_interface/Solver_interface.txt
index 3df20d90a0c..cc021566810 100644
--- a/Solver_interface/doc/Solver_interface/Solver_interface.txt
+++ b/Solver_interface/doc/Solver_interface/Solver_interface.txt
@@ -64,11 +64,17 @@ and this solver:
 
 \section SectionSolverSparse Sparse Solvers
 
+We define 3 concepts for sparse linear algebra:
+
+- `SparseLinearAlgebraTraits_d`
+- `SparseLinearAlgebraTraitsWithFactor_d`
+- `NormalEquationSparseLinearAlgebraTraits_d`
+
 An interface to the sparse solvers from the \ref thirdpartyEigen
-library is provided through the class `Eigen_solver_traits<T>`. This
-solver traits class can be used for an iterative or a direct,
-symmetric or general sparse solvers. The specific solver to be used
-must be given as template parameter.
+library is provided as a model for these 3 concepts through the class
+`Eigen_solver_traits<T>`. This solver traits class can be used for an
+iterative or a direct, symmetric or general sparse solvers. The
+specific solver to be used must be given as template parameter.
 
 Each \cgal package using a sparse solver specifies which type of matrix
 and solver is required: