diff --git a/src/core/pla.cpp b/src/core/pla.cpp
index a679deb..f554cd8 100644
--- a/src/core/pla.cpp
+++ b/src/core/pla.cpp
@@ -8,32 +8,13 @@ typedef storm::storage::ParameterRegion<storm::RationalFunction> Region;
 void specifyFormula(std::shared_ptr<PLAChecker>& checker, std::shared_ptr<const storm::logic::Formula> const& formula) {
     checker->specifyFormula(storm::modelchecker::CheckTask<storm::logic::Formula, storm::RationalFunction>(*formula, true));
 }
-storm::modelchecker::parametric::RegionCheckResult checkRegion(std::shared_ptr<PLAChecker>& checker, Region& region) {
-    return checker->analyzeRegion(region, storm::modelchecker::parametric::RegionCheckResult::Unknown, true);
+storm::modelchecker::parametric::RegionCheckResult checkRegion(std::shared_ptr<PLAChecker>& checker, Region& region, storm::modelchecker::parametric::RegionCheckResult initialResult, bool sampleVertices) {
+    return checker->analyzeRegion(region, initialResult, sampleVertices);
 }
 
 // Define python bindings
 void define_pla(py::module& m) {
     
-    // PLAChecker
-    py::class_<PLAChecker, std::shared_ptr<PLAChecker>>(m, "PLAChecker", "Region model checker for sparse DTMCs")
-        .def("__init__", [](PLAChecker& instance, std::shared_ptr<storm::models::sparse::Dtmc<storm::RationalFunction>> model) -> void {
-                new (&instance) PLAChecker(*model);
-            })
-        //.def(py::init<storm::models::sparse::Dtmc<storm::RationalFunction>>)
-        .def("specify_formula", &specifyFormula, "Specify formula", py::arg("formula"))
-        .def("check_region", &checkRegion, "Check region", py::arg("region"))
-    ;
-    
-    // Region
-    py::class_<Region, std::shared_ptr<Region>>(m, "ParameterRegion", "Parameter region")
-       .def("__init__", [](Region &instance, std::string const& regionString, std::set<Region::VariableType> const& variables) -> void {
-                new (&instance) Region(Region::parseRegion(regionString, variables));
-            })
-        //.def(py::init<Region::VariableSubstitutionType &, Region::VariableSubstitutionType &>(), py::arg("lowerBounds"), py::arg("upperBounds"))
-        //.def("result", &Region::getCheckResult, "Get check result")
-    ;
-
     // RegionCheckResult 
     py::enum_<storm::modelchecker::parametric::RegionCheckResult>(m, "RegionCheckResult", "Types of region check results")
         .value("EXISTSSAT", storm::modelchecker::parametric::RegionCheckResult::ExistsSat)
@@ -46,4 +27,21 @@ void define_pla(py::module& m) {
         .value("UNKNOWN", storm::modelchecker::parametric::RegionCheckResult::Unknown)
         .def("__str__", &streamToString<storm::modelchecker::parametric::RegionCheckResult>)
     ;
+
+    // Region
+    py::class_<Region, std::shared_ptr<Region>>(m, "ParameterRegion", "Parameter region")
+       .def("__init__", [](Region &instance, std::string const& regionString, std::set<Region::VariableType> const& variables) -> void {
+                new (&instance) Region(Region::parseRegion(regionString, variables));
+            })
+        //.def(py::init<Region::VariableSubstitutionType &, Region::VariableSubstitutionType &>(), py::arg("lowerBounds"), py::arg("upperBounds"))
+    ;
+
+    // PLAChecker
+    py::class_<PLAChecker, std::shared_ptr<PLAChecker>>(m, "PLAChecker", "Region model checker for sparse DTMCs")
+        .def("__init__", [](PLAChecker& instance, std::shared_ptr<storm::models::sparse::Dtmc<storm::RationalFunction>> model) -> void {
+                new (&instance) PLAChecker(*model);
+            })
+        .def("specify_formula", &specifyFormula, "Specify formula", py::arg("formula"))
+        .def("check_region", &checkRegion, "Check region", py::arg("region"), py::arg("initialResult") = storm::modelchecker::parametric::RegionCheckResult::Unknown, py::arg("sampleVertices") = false)
+    ;
 }
diff --git a/tests/core/test_pla.py b/tests/core/test_pla.py
index 03fa2bb..be48f7a 100644
--- a/tests/core/test_pla.py
+++ b/tests/core/test_pla.py
@@ -35,7 +35,7 @@ class TestModelChecking:
         #upperBounds = {pL: 0.65, pK: 0.95}
         #region = stormpy.ParameterRegion(lowerBounds, upperBounds)
         region = stormpy.ParameterRegion("0.4<=pL<=0.65,0.75<=pK<=0.95", parameters)
-        result = checker.check_region(region)
+        result = checker.check_region(region, stormpy.RegionCheckResult.UNKNOWN, True)
         assert result == stormpy.RegionCheckResult.EXISTSBOTH
         #lowerBounds = {pL: 0.1, pK: 0.2}
         #upperBounds = {pL: 0.73, pK: 0.715}