diff --git a/owlapy/converter.py b/owlapy/converter.py
index 75979c9..8a8a2f8 100644
--- a/owlapy/converter.py
+++ b/owlapy/converter.py
@@ -624,10 +624,10 @@ def as_query(self,
             q = [f"VALUES {root_variable} {{ "]
             for x in values:
                 q.append(f"<{x.to_string_id()}>")
-            q.append("}} . ")
+            q.append("} . ")
             qs.extend(q)
         qs.extend(tp)
-        qs.append(" }}")
+        qs.append(" }")
 
 
         query = "\n".join(qs)
diff --git a/tests/test_owlapy_owl2sparql_converter.py b/tests/test_owlapy_owl2sparql_converter.py
index 398df23..b240cb7 100644
--- a/tests/test_owlapy_owl2sparql_converter.py
+++ b/tests/test_owlapy_owl2sparql_converter.py
@@ -8,14 +8,14 @@
 from owlapy.iri import IRI
 from owlapy.owl_property import OWLObjectProperty
 
-# from owlapy.owl_ontology_manager import OntologyManager
-# from owlapy.owl_reasoner import OntologyReasoner, FastInstanceCheckerReasoner
-# from owlapy.parser import DLSyntaxParser
-# from rdflib import Graph
+from owlapy.owl_ontology_manager import OntologyManager
+from owlapy.owl_reasoner import OntologyReasoner, FastInstanceCheckerReasoner
+from owlapy.parser import DLSyntaxParser
+from rdflib import Graph
 from owlapy.converter import Owl2SparqlConverter
 
 
-PATH_FAMILY = '../KGs/Family/family-benchmark_rich_background.owl'
+PATH_FAMILY = 'KGs/Family/family-benchmark_rich_background.owl'
 
 
 # checks whether all individuals returned by the reasoner are found in results generated by the sparql query
@@ -93,164 +93,164 @@ def test_as_query(self):
 #  )"""
         self.assertEqual(query, query_t)  # add assertion here
 
-    # def test_Single(self):
-    #     # rdf graph - using rdflib
-    #     family_rdf_graph = Graph()
-    #     family_rdf_graph.parse(location=PATH_FAMILY)
-    #     # knowledge base - using OWLReasoner
-    #     mgr = OntologyManager()
-    #     onto = mgr.load_ontology(IRI.create(PATH_FAMILY))
-    #     base_reasoner = OntologyReasoner(onto)
-    #     family_kb_reasoner = FastInstanceCheckerReasoner(onto, base_reasoner=base_reasoner, negation_default=True)
-    #
-    #     ce_str = "Brother"
-    #     ce_parsed = DLSyntaxParser(namespace="http://www.benchmark.org/family#").parse_expression(expression_str=ce_str)
-    #     actual_query = Owl2SparqlConverter().as_query(root_variable=self._root_var_, ce=ce_parsed, count=False,
-    #                                                   values=None, named_individuals=True)
-    #     expected_query = """SELECT DISTINCT ?x
-    #                         WHERE {
-    #                             ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.benchmark.org/family#Brother> .
-    #                         }"""
-    #
-    #     sparql_results_actual = family_rdf_graph.query(actual_query)
-    #     sparql_results_expected = family_rdf_graph.query(expected_query)
-    #     reasoner_results = set(family_kb_reasoner.instances(ce_parsed))
-    #
-    #     self.assertEqual(len(sparql_results_actual), len(sparql_results_expected))
-    #     self.assertEqual(len(sparql_results_actual), len(reasoner_results))
-    #     self.assertTrue(check_reasoner_instances_in_sparql_results(sparql_results_actual, reasoner_results))
-    #
-    #     ce_str = "Male"
-    #     ce_parsed = DLSyntaxParser(namespace="http://www.benchmark.org/family#").parse_expression(expression_str=ce_str)
-    #     actual_query = Owl2SparqlConverter().as_query(root_variable=self._root_var_, ce=ce_parsed, count=False,
-    #                                                   values=None, named_individuals=True)
-    #     expected_query = """SELECT DISTINCT ?x
-    #                                 WHERE {
-    #                                     ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.benchmark.org/family#Male> .
-    #                                 }"""
-    #
-    #     sparql_results_actual = family_rdf_graph.query(actual_query)
-    #     sparql_results_expected = family_rdf_graph.query(expected_query)
-    #     reasoner_results = set(family_kb_reasoner.instances(ce_parsed))
-    #
-    #     self.assertEqual(len(sparql_results_actual), len(sparql_results_expected))
-    #     self.assertEqual(len(sparql_results_actual), len(reasoner_results))
-    #     self.assertTrue(check_reasoner_instances_in_sparql_results(sparql_results_actual, reasoner_results))
-    #
-    # def test_Intersection(self):
-    #     # rdf graph - using rdflib
-    #     family_rdf_graph = Graph()
-    #     family_rdf_graph.parse(location=PATH_FAMILY)
-    #     # knowledge base - using OWLReasoner
-    #     mgr = OntologyManager()
-    #     onto = mgr.load_ontology(IRI.create(PATH_FAMILY))
-    #     base_reasoner = OntologyReasoner(onto)
-    #     family_kb_reasoner = FastInstanceCheckerReasoner(onto, base_reasoner=base_reasoner, negation_default=True)
-    #
-    #     ce_str = "Brother ⊓ Father"
-    #     ce_parsed = DLSyntaxParser(namespace="http://www.benchmark.org/family#").parse_expression(expression_str=ce_str)
-    #     actual_query = Owl2SparqlConverter().as_query(root_variable=self._root_var_, ce=ce_parsed, count=False,
-    #                                                   values=None, named_individuals=True)
-    #     expected_query = """SELECT DISTINCT ?x
-    #                         WHERE {
-    #                             ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.benchmark.org/family#Brother> .
-    #                             ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.benchmark.org/family#Father> .
-    #                         }"""
-    #
-    #     sparql_results_actual = family_rdf_graph.query(actual_query)
-    #     sparql_results_expected = family_rdf_graph.query(expected_query)
-    #     reasoner_results = set(family_kb_reasoner.instances(ce_parsed))
-    #
-    #     self.assertEqual(len(sparql_results_actual), len(sparql_results_expected))
-    #     self.assertEqual(len(sparql_results_actual), len(reasoner_results))
-    #     self.assertTrue(check_reasoner_instances_in_sparql_results(sparql_results_actual, reasoner_results))
-    #
-    # def test_Union(self):
-    #     # rdf graph - using rdflib
-    #     family_rdf_graph = Graph()
-    #     family_rdf_graph.parse(location=PATH_FAMILY)
-    #     # knowledge base - using OWLReasoner
-    #     mgr = OntologyManager()
-    #     onto = mgr.load_ontology(IRI.create(PATH_FAMILY))
-    #     base_reasoner = OntologyReasoner(onto)
-    #     family_kb_reasoner = FastInstanceCheckerReasoner(onto, base_reasoner=base_reasoner, negation_default=True)
-    #
-    #     ce_str = "Sister ⊔ Mother"
-    #     ce_parsed = DLSyntaxParser(namespace="http://www.benchmark.org/family#").parse_expression(expression_str=ce_str)
-    #     actual_query = Owl2SparqlConverter().as_query(root_variable=self._root_var_, ce=ce_parsed, count=False,
-    #                                                   values=None, named_individuals=True)
-    #     expected_query = """SELECT DISTINCT ?x
-    #                         WHERE {
-    #                             { ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.benchmark.org/family#Sister> . }
-    #                             UNION
-    #                             { ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.benchmark.org/family#Mother> . }
-    #                         }"""
-    #
-    #     sparql_results_actual = family_rdf_graph.query(actual_query)
-    #     sparql_results_expected = family_rdf_graph.query(expected_query)
-    #     reasoner_results = set(family_kb_reasoner.instances(ce_parsed))
-    #
-    #     self.assertEqual(len(sparql_results_actual), len(sparql_results_expected))
-    #     self.assertEqual(len(sparql_results_actual), len(reasoner_results))
-    #     self.assertTrue(check_reasoner_instances_in_sparql_results(sparql_results_actual, reasoner_results))
-    #
-    # def test_Complement(self):
-    #     # rdf graph - using rdflib
-    #     family_rdf_graph = Graph()
-    #     family_rdf_graph.parse(location=PATH_FAMILY)
-    #     # knowledge base - using OWLReasoner
-    #     mgr = OntologyManager()
-    #     onto = mgr.load_ontology(IRI.create(PATH_FAMILY))
-    #     base_reasoner = OntologyReasoner(onto)
-    #     family_kb_reasoner = FastInstanceCheckerReasoner(onto, base_reasoner=base_reasoner, negation_default=True)
-    #
-    #     ce_str = "¬Mother"
-    #     ce_parsed = DLSyntaxParser(namespace="http://www.benchmark.org/family#").parse_expression(expression_str=ce_str)
-    #     actual_query = Owl2SparqlConverter().as_query(root_variable=self._root_var_, ce=ce_parsed, count=False,
-    #                                                   values=None, named_individuals=True)
-    #     expected_query = """SELECT DISTINCT ?x
-    #                         WHERE {
-    #                                 ?x a <http://www.w3.org/2002/07/owl#NamedIndividual> .
-    #                                 ?x ?p ?o .
-    #                                 FILTER NOT EXISTS { ?x a <http://www.benchmark.org/family#Mother> . }
-    #                         }"""
-    #
-    #     sparql_results_actual = family_rdf_graph.query(actual_query)
-    #     sparql_results_expected = family_rdf_graph.query(expected_query)
-    #     reasoner_results = set(family_kb_reasoner.instances(ce_parsed))
-    #
-    #     self.assertEqual(len(sparql_results_actual), len(sparql_results_expected))
-    #     self.assertEqual(len(sparql_results_actual), len(reasoner_results))
-    #     self.assertTrue(check_reasoner_instances_in_sparql_results(sparql_results_actual, reasoner_results))
-    #
-    # def test_Exists(self):
-    #     # rdf graph - using rdflib
-    #     family_rdf_graph = Graph()
-    #     family_rdf_graph.parse(location=PATH_FAMILY)
-    #     # knowledge base - using OWLReasoner
-    #     mgr = OntologyManager()
-    #     onto = mgr.load_ontology(IRI.create(PATH_FAMILY))
-    #     base_reasoner = OntologyReasoner(onto)
-    #     family_kb_reasoner = FastInstanceCheckerReasoner(onto, base_reasoner=base_reasoner, negation_default=True)
-    #
-    #     ce_str = "∃hasChild.Male"
-    #     ce_parsed = DLSyntaxParser(namespace="http://www.benchmark.org/family#").parse_expression(expression_str=ce_str)
-    #     actual_query = Owl2SparqlConverter().as_query(root_variable=self._root_var_, ce=ce_parsed, count=False,
-    #                                                   values=None, named_individuals=True)
-    #     expected_query = """SELECT DISTINCT ?x
-    #                         WHERE {
-    #                             ?x <http://www.benchmark.org/family#hasChild> ?s .
-    #                             ?s a <http://www.benchmark.org/family#Male> .
-    #                         }"""
-    #
-    #     sparql_results_actual = family_rdf_graph.query(actual_query)
-    #     sparql_results_expected = family_rdf_graph.query(expected_query)
-    #     reasoner_results = set(family_kb_reasoner.instances(ce_parsed))
-    #
-    #     self.assertEqual(len(sparql_results_actual), len(sparql_results_expected))
-    #     self.assertEqual(len(sparql_results_actual), len(reasoner_results))
-    #     self.assertTrue(check_reasoner_instances_in_sparql_results(sparql_results_actual, reasoner_results))
-    #
+    def test_Single(self):
+        # rdf graph - using rdflib
+        family_rdf_graph = Graph()
+        family_rdf_graph.parse(location=PATH_FAMILY)
+        # knowledge base - using OWLReasoner
+        mgr = OntologyManager()
+        onto = mgr.load_ontology(IRI.create(PATH_FAMILY))
+        base_reasoner = OntologyReasoner(onto)
+        family_kb_reasoner = FastInstanceCheckerReasoner(onto, base_reasoner=base_reasoner, negation_default=True)
+
+        ce_str = "Brother"
+        ce_parsed = DLSyntaxParser(namespace="http://www.benchmark.org/family#").parse_expression(expression_str=ce_str)
+        actual_query = Owl2SparqlConverter().as_query(root_variable=self._root_var_, ce=ce_parsed, count=False,
+                                                      values=None, named_individuals=True)
+        expected_query = """SELECT DISTINCT ?x
+                            WHERE {
+                                ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.benchmark.org/family#Brother> .
+                            }"""
+
+        sparql_results_actual = family_rdf_graph.query(actual_query)
+        sparql_results_expected = family_rdf_graph.query(expected_query)
+        reasoner_results = set(family_kb_reasoner.instances(ce_parsed))
+
+        self.assertEqual(len(sparql_results_actual), len(sparql_results_expected))
+        self.assertEqual(len(sparql_results_actual), len(reasoner_results))
+        self.assertTrue(check_reasoner_instances_in_sparql_results(sparql_results_actual, reasoner_results))
+
+        ce_str = "Male"
+        ce_parsed = DLSyntaxParser(namespace="http://www.benchmark.org/family#").parse_expression(expression_str=ce_str)
+        actual_query = Owl2SparqlConverter().as_query(root_variable=self._root_var_, ce=ce_parsed, count=False,
+                                                      values=None, named_individuals=True)
+        expected_query = """SELECT DISTINCT ?x
+                                    WHERE {
+                                        ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.benchmark.org/family#Male> .
+                                    }"""
+
+        sparql_results_actual = family_rdf_graph.query(actual_query)
+        sparql_results_expected = family_rdf_graph.query(expected_query)
+        reasoner_results = set(family_kb_reasoner.instances(ce_parsed))
+
+        self.assertEqual(len(sparql_results_actual), len(sparql_results_expected))
+        self.assertEqual(len(sparql_results_actual), len(reasoner_results))
+        self.assertTrue(check_reasoner_instances_in_sparql_results(sparql_results_actual, reasoner_results))
+
+    def test_Intersection(self):
+        # rdf graph - using rdflib
+        family_rdf_graph = Graph()
+        family_rdf_graph.parse(location=PATH_FAMILY)
+        # knowledge base - using OWLReasoner
+        mgr = OntologyManager()
+        onto = mgr.load_ontology(IRI.create(PATH_FAMILY))
+        base_reasoner = OntologyReasoner(onto)
+        family_kb_reasoner = FastInstanceCheckerReasoner(onto, base_reasoner=base_reasoner, negation_default=True)
+
+        ce_str = "Brother ⊓ Father"
+        ce_parsed = DLSyntaxParser(namespace="http://www.benchmark.org/family#").parse_expression(expression_str=ce_str)
+        actual_query = Owl2SparqlConverter().as_query(root_variable=self._root_var_, ce=ce_parsed, count=False,
+                                                      values=None, named_individuals=True)
+        expected_query = """SELECT DISTINCT ?x
+                            WHERE {
+                                ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.benchmark.org/family#Brother> .
+                                ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.benchmark.org/family#Father> .
+                            }"""
+
+        sparql_results_actual = family_rdf_graph.query(actual_query)
+        sparql_results_expected = family_rdf_graph.query(expected_query)
+        reasoner_results = set(family_kb_reasoner.instances(ce_parsed))
+
+        self.assertEqual(len(sparql_results_actual), len(sparql_results_expected))
+        self.assertEqual(len(sparql_results_actual), len(reasoner_results))
+        self.assertTrue(check_reasoner_instances_in_sparql_results(sparql_results_actual, reasoner_results))
+
+    def test_Union(self):
+        # rdf graph - using rdflib
+        family_rdf_graph = Graph()
+        family_rdf_graph.parse(location=PATH_FAMILY)
+        # knowledge base - using OWLReasoner
+        mgr = OntologyManager()
+        onto = mgr.load_ontology(IRI.create(PATH_FAMILY))
+        base_reasoner = OntologyReasoner(onto)
+        family_kb_reasoner = FastInstanceCheckerReasoner(onto, base_reasoner=base_reasoner, negation_default=True)
+
+        ce_str = "Sister ⊔ Mother"
+        ce_parsed = DLSyntaxParser(namespace="http://www.benchmark.org/family#").parse_expression(expression_str=ce_str)
+        actual_query = Owl2SparqlConverter().as_query(root_variable=self._root_var_, ce=ce_parsed, count=False,
+                                                      values=None, named_individuals=True)
+        expected_query = """SELECT DISTINCT ?x
+                            WHERE {
+                                { ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.benchmark.org/family#Sister> . }
+                                UNION
+                                { ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.benchmark.org/family#Mother> . }
+                            }"""
+
+        sparql_results_actual = family_rdf_graph.query(actual_query)
+        sparql_results_expected = family_rdf_graph.query(expected_query)
+        reasoner_results = set(family_kb_reasoner.instances(ce_parsed))
+
+        self.assertEqual(len(sparql_results_actual), len(sparql_results_expected))
+        self.assertEqual(len(sparql_results_actual), len(reasoner_results))
+        self.assertTrue(check_reasoner_instances_in_sparql_results(sparql_results_actual, reasoner_results))
+
+    def test_Complement(self):
+        # rdf graph - using rdflib
+        family_rdf_graph = Graph()
+        family_rdf_graph.parse(location=PATH_FAMILY)
+        # knowledge base - using OWLReasoner
+        mgr = OntologyManager()
+        onto = mgr.load_ontology(IRI.create(PATH_FAMILY))
+        base_reasoner = OntologyReasoner(onto)
+        family_kb_reasoner = FastInstanceCheckerReasoner(onto, base_reasoner=base_reasoner, negation_default=True)
+
+        ce_str = "¬Mother"
+        ce_parsed = DLSyntaxParser(namespace="http://www.benchmark.org/family#").parse_expression(expression_str=ce_str)
+        actual_query = Owl2SparqlConverter().as_query(root_variable=self._root_var_, ce=ce_parsed, count=False,
+                                                      values=None, named_individuals=True)
+        expected_query = """SELECT DISTINCT ?x
+                            WHERE {
+                                    ?x a <http://www.w3.org/2002/07/owl#NamedIndividual> .
+                                    ?x ?p ?o .
+                                    FILTER NOT EXISTS { ?x a <http://www.benchmark.org/family#Mother> . }
+                            }"""
+
+        sparql_results_actual = family_rdf_graph.query(actual_query)
+        sparql_results_expected = family_rdf_graph.query(expected_query)
+        reasoner_results = set(family_kb_reasoner.instances(ce_parsed))
+
+        self.assertEqual(len(sparql_results_actual), len(sparql_results_expected))
+        self.assertEqual(len(sparql_results_actual), len(reasoner_results))
+        self.assertTrue(check_reasoner_instances_in_sparql_results(sparql_results_actual, reasoner_results))
+
+    def test_Exists(self):
+        # rdf graph - using rdflib
+        family_rdf_graph = Graph()
+        family_rdf_graph.parse(location=PATH_FAMILY)
+        # knowledge base - using OWLReasoner
+        mgr = OntologyManager()
+        onto = mgr.load_ontology(IRI.create(PATH_FAMILY))
+        base_reasoner = OntologyReasoner(onto)
+        family_kb_reasoner = FastInstanceCheckerReasoner(onto, base_reasoner=base_reasoner, negation_default=True)
+
+        ce_str = "∃hasChild.Male"
+        ce_parsed = DLSyntaxParser(namespace="http://www.benchmark.org/family#").parse_expression(expression_str=ce_str)
+        actual_query = Owl2SparqlConverter().as_query(root_variable=self._root_var_, ce=ce_parsed, count=False,
+                                                      values=None, named_individuals=True)
+        expected_query = """SELECT DISTINCT ?x
+                            WHERE {
+                                ?x <http://www.benchmark.org/family#hasChild> ?s .
+                                ?s a <http://www.benchmark.org/family#Male> .
+                            }"""
+
+        sparql_results_actual = family_rdf_graph.query(actual_query)
+        sparql_results_expected = family_rdf_graph.query(expected_query)
+        reasoner_results = set(family_kb_reasoner.instances(ce_parsed))
+
+        self.assertEqual(len(sparql_results_actual), len(sparql_results_expected))
+        self.assertEqual(len(sparql_results_actual), len(reasoner_results))
+        self.assertTrue(check_reasoner_instances_in_sparql_results(sparql_results_actual, reasoner_results))
+
     # def test_ForAll(self):
     #     # rdf graph - using rdflib
     #     family_rdf_graph = Graph()