diff --git a/hw4-pybind/pypart.cc b/hw4-pybind/pypart.cc
index 6b9e8c94..1d821a6a 100644
--- a/hw4-pybind/pypart.cc
+++ b/hw4-pybind/pypart.cc
@@ -1,83 +1,85 @@
 #include <functional>
 #include <iostream>
 #include <pybind11/pybind11.h>
 
 #include "material_points_factory.hh"
 #include "ping_pong_balls_factory.hh"
 #include "planets_factory.hh"
 
 #include "compute.hh"
 #include "compute_temperature.hh"
 #include "compute_gravity.hh"
 #include "compute_verlet_integration.hh"
 #include "compute_interaction.hh"
 
 #include "csv_writer.hh"
 
 #include "system.hh"
 #include "system_evolution.hh"
 
 namespace py = pybind11;
 
 PYBIND11_MODULE(pypart, m) {
     m.doc() = "pybind pypart plugin"; // optional docstring
     // The member functions of the various classes (used in main.py) are exposed to pybind
 
     // Exercise 1 - Question 1, 2, 3
     py::class_<ParticlesFactoryInterface>(m, "ParticlesFactoryInterface")
         .def("getInstance", &ParticlesFactoryInterface::getInstance, py::return_value_policy::reference)
+        .def("createSimulation",(SystemEvolution & (ParticlesFactoryInterface::*)(const std::string &, Real))
+            &ParticlesFactoryInterface::createSimulation, py::return_value_policy::reference)
         .def("createSimulation",py::overload_cast<const std::string &, Real,
                 py::function>(&ParticlesFactoryInterface::createSimulation<py::function>),
                 py::return_value_policy::reference)
         //.def("createSimulation", &ParticlesFactoryInterface::createSimulation,py::return_value_policy::reference)
         //.def("createSimulation",py::overload_cast<const std::string &, Real,py::function>(&ParticlesFactoryInterface::createSimulation<py::function>),py::return_value_policy::reference)
         .def_property_readonly("system_evolution", &ParticlesFactoryInterface::getSystemEvolution);
     py::class_<MaterialPointsFactory, ParticlesFactoryInterface>(m, "MaterialPointsFactory")
         .def("getInstance", &MaterialPointsFactory::getInstance, py::return_value_policy::reference)
         .def("createSimulation",py::overload_cast<const std::string &, Real,
                 py::function>(&ParticlesFactoryInterface::createSimulation<py::function>),
                 py::return_value_policy::reference);
         //.def("createSimulation",(SystemEvolution & (MaterialPointsFactory::*)(const std::string &, Real))&MaterialPointsFactory::createSimulation, py::return_value_policy::reference);
         //.def("createSimulation",py::overload_cast<const std::string &, Real,py::function>(&MaterialPointsFactory::createSimulation<py::function>), py::return_value_policy::reference);
     py::class_<PingPongBallsFactory, ParticlesFactoryInterface>(m, "PingPongBallsFactory")
-        .def("getInstance", &PingPongBallsFactory::getInstance, py::return_value_policy::reference)
-        .def("createSimulation",py::overload_cast<const std::string &, Real,
-                py::function>(&ParticlesFactoryInterface::createSimulation<py::function>),
-                py::return_value_policy::reference);
+        .def("getInstance", &PingPongBallsFactory::getInstance, py::return_value_policy::reference);
+        //.def("createSimulation",py::overload_cast<const std::string &, Real,
+        //        py::function>(&ParticlesFactoryInterface::createSimulation<py::function>),
+        //        py::return_value_policy::reference);
         //.def("createSimulation", &PingPongBallsFactory::createSimulation,py::return_value_policy::reference);
     py::class_<PlanetsFactory, ParticlesFactoryInterface>(m, "PlanetsFactory")
-        .def("getInstance", &PlanetsFactory::getInstance, py::return_value_policy::reference)
-        .def("createSimulation",py::overload_cast<const std::string &, Real,
-                py::function>(&ParticlesFactoryInterface::createSimulation<py::function>),
-                py::return_value_policy::reference);
+        .def("getInstance", &PlanetsFactory::getInstance, py::return_value_policy::reference);
+        //.def("createSimulation",py::overload_cast<const std::string &, Real,
+        //        py::function>(&ParticlesFactoryInterface::createSimulation<py::function>),
+        //        py::return_value_policy::reference);
         //.def("createSimulation", &PlanetsFactory::createSimulation,py::return_value_policy::reference);
 
     // Exercise 2 - Question 1, 2, 3
     py::class_<Compute, std::shared_ptr<Compute>>(m, "Compute");  //To try: for memory conflict problem maybe: std::shared_ptr<Compute> :NO
     py::class_<ComputeInteraction, Compute, std::shared_ptr<ComputeInteraction>>(m, "ComputeInteraction");
     py::class_<ComputeTemperature, Compute, std::shared_ptr<ComputeTemperature>>(m, "ComputeTemperature") // (tried: py::dynamic_attr())
         .def(py::init<>())
         .def_property_readonly("conductivity", &ComputeTemperature::getConductivity)
         .def_property_readonly("capacity", &ComputeTemperature::getCapacity)
         .def_property_readonly("L", &ComputeTemperature::getL)
         .def_property_readonly("deltat", &ComputeTemperature::getDeltat);
     py::class_<ComputeGravity, Compute, std::shared_ptr<ComputeGravity>>(m, "ComputeGravity")
         .def(py::init<>())
         .def("setG", &ComputeGravity::setG);
     py::class_<ComputeVerletIntegration, Compute, std::shared_ptr<ComputeVerletIntegration>>(m, "ComputeVerletIntegration")
         .def(py::init<Real>())
         .def("addInteraction", &ComputeVerletIntegration::addInteraction);
 
     // Exercise 3 - Question 1
     py::class_<CsvWriter>(m, "CsvWriter")
         .def(py::init<const std::string&>())
         .def("write", &CsvWriter::write);
     py::class_<SystemEvolution>(m, "SystemEvolution") // no heritage but referenced : strange ! system_evolution in main.py !?
         .def("evolve", &SystemEvolution::evolve)
         .def("addCompute", &SystemEvolution::addCompute)
         .def("getSystem", &SystemEvolution::getSystem)
         .def("setNSteps", &SystemEvolution::setNSteps)
         .def("setDumpFreq", &SystemEvolution::setDumpFreq);
     py::class_<System>(m, "System"); // not necessary but added for clarity
 
 }