diff --git a/paynt/quotient/mdp.py b/paynt/quotient/mdp.py
index 13de30bf..e2e32d9b 100644
--- a/paynt/quotient/mdp.py
+++ b/paynt/quotient/mdp.py
@@ -188,11 +188,9 @@ def to_graphviz(self, graphviz_tree, variables, action_labels):
 
 class DecisionTree:
 
-    def __init__(self, quotient, variable_name, state_valuations):
+    def __init__(self, quotient, variables, state_valuations):
         self.quotient = quotient
         self.state_valuations = state_valuations
-        variables = [Variable(var,var_name,state_valuations) for var,var_name in enumerate(variable_name)]
-        variables = [v for v in variables if len(v.domain) > 1]
         self.variables = variables
         logger.debug(f"found the following {len(self.variables)} variables: {[str(v) for v in self.variables]}")
         self.reset()
@@ -276,8 +274,11 @@ def __init__(self, mdp, specification):
             valuation = json.loads(str(sv.get_json(state)))
             valuation = [valuation[var_name] for var_name in variable_name]
             state_valuations.append(valuation)
-        self.decision_tree = DecisionTree(self,variable_name,state_valuations)
+        self.state_valuations = state_valuations
+        variables = [Variable(var,var_name,state_valuations) for var,var_name in enumerate(variable_name)]
+        self.variables = [v for v in variables if len(v.domain) > 1]
 
+        self.decision_tree = None
         self.coloring = None
         self.family = None
         self.splitter_count = None
@@ -285,11 +286,12 @@ def __init__(self, mdp, specification):
     def decide(self, node, var_name):
         node.set_variable_by_name(var_name,self.decision_tree)
 
-    '''
-    Build the design space and coloring corresponding to the current decision tree.
-    '''
-    def set_depth(self, depth):
+    def reset_tree(self, depth):
+        '''
+        Rebuild the decision tree template, the design space and the coloring.
+        '''
         logger.debug(f"synthesizing tree of depth {depth}")
+        self.decision_tree = DecisionTree(self,self.variables,self.state_valuations)
         self.decision_tree.set_depth(depth)
 
         # logger.debug("building coloring...")
diff --git a/paynt/synthesizer/decision_tree.py b/paynt/synthesizer/decision_tree.py
index 55fee6df..1a182dae 100644
--- a/paynt/synthesizer/decision_tree.py
+++ b/paynt/synthesizer/decision_tree.py
@@ -118,7 +118,7 @@ def export_decision_tree(self, decision_tree, export_filename_base):
 
     def synthesize_tree(self, depth:int):
         self.counters_reset()
-        self.quotient.set_depth(depth)
+        self.quotient.reset_tree(depth)
         self.best_assignment = self.best_assignment_value = None
         self.synthesize(keep_optimum=True)
         if self.best_assignment is not None:
@@ -135,7 +135,8 @@ def synthesize_tree_sequence(self, opt_result_value):
         if global_timeout is None: global_timeout = 1800
         depth_timeout = global_timeout / 2 / SynthesizerDecisionTree.tree_depth
         for depth in range(SynthesizerDecisionTree.tree_depth+1):
-            self.quotient.set_depth(depth)
+            print()
+            self.quotient.reset_tree(depth)
             best_assignment_old = self.best_assignment
 
             family = self.quotient.family
@@ -150,7 +151,7 @@ def synthesize_tree_sequence(self, opt_result_value):
 
             if SynthesizerDecisionTree.use_tree_hint and self.best_tree is not None:
                 subfamily = family.copy()
-                self.quotient.decision_tree.root.apply_hint(subfamily,self.best_tree)
+                self.quotient.decision_tree.root.apply_hint(subfamily,self.best_tree.root)
                 families = [subfamily,family]
 
             for family in families:
@@ -170,13 +171,13 @@ def synthesize_tree_sequence(self, opt_result_value):
                     result = dtmc.check_specification(self.quotient.specification)
                     logger.info(f"double-checking specification satisfiability: {result}")
 
+                self.best_tree = self.quotient.decision_tree
+                self.best_tree.root.associate_assignment(self.best_assignment)
+                self.best_tree_value = self.best_assignment_value
+
                 if abs( (self.best_assignment_value-opt_result_value)/opt_result_value ) < 1e-3:
                     break
 
-                self.best_tree = self.quotient.decision_tree.root
-                self.best_tree.associate_assignment(self.best_assignment)
-                self.best_tree_value = self.best_assignment_value
-
             if self.resource_limit_reached():
                 break
 
diff --git a/paynt/synthesizer/synthesizer_ar.py b/paynt/synthesizer/synthesizer_ar.py
index 1af7788c..f09a412d 100644
--- a/paynt/synthesizer/synthesizer_ar.py
+++ b/paynt/synthesizer/synthesizer_ar.py
@@ -100,7 +100,7 @@ def update_optimum(self, family):
         self.quotient.specification.optimality.update_optimum(iv)
         self.best_assignment = ia
         self.best_assignment_value = iv
-        # logger.info(f"value {round(iv,4)} achieved after {round(paynt.utils.timer.GlobalTimer.read(),2)} seconds")
+        logger.info(f"value {round(iv,4)} achieved after {round(paynt.utils.timer.GlobalTimer.read(),2)} seconds")
         if isinstance(self.quotient, paynt.quotient.pomdp.PomdpQuotient):
             self.stat.new_fsc_found(family.analysis_result.improving_value, ia, self.quotient.policy_size(ia))