diff --git a/Planning/my_planning_graph.py b/Planning/my_planning_graph.py
index 47b3299..8d68c8c 100755
--- a/Planning/my_planning_graph.py
+++ b/Planning/my_planning_graph.py
@@ -304,13 +304,14 @@ def add_action_level(self, level):
         :return:
             adds A nodes to the current level in self.a_levels[level]
         '''
-        # TODO add action A level to the planning graph as described in the Russell-Norvig text
-        # 1. determine what actions to add and create those PgNode_a objects
-        # 2. connect the nodes to the previous S literal level
-        # for example, the A0 level will iterate through all possible actions for the problem and add a PgNode_a to a_levels[0]
-        #   set iff all prerequisite literals for the action hold in S0.  This can be accomplished by testing
-        #   to see if a proposed PgNode_a has prenodes that are a subset of the previous S level.  Once an
-        #   action node is added, it MUST be connected to the S node instances in the appropriate s_level set.
+        self.a_levels.append(set())       
+        for action in self.all_actions:
+            candidate_a = PgNode_a(action)   
+            if candidate_a.prenodes.issubset(self.s_levels[level]):
+                for node_s in self.s_levels[level]:
+                    self.a_levels[level].add(candidate_a)
+                    candidate_a.parents.add(node_s)
+                    node_s.children.add(candidate_a)
 
     def add_literal_level(self, level):
         ''' add an S (literal) level to the Planning Graph
@@ -329,6 +330,12 @@ def add_literal_level(self, level):
         #   may be "added" to the set without fear of duplication.  However, it is important to then correctly create and connect
         #   all of the new S nodes as children of all the A nodes that could produce them, and likewise add the A nodes to the
         #   parent sets of the S nodes
+        self.s_levels.append(set()) 
+        for node_a in self.a_levels[level-1]:
+            for node_s in node_a.effnodes: # states that the action could produce
+                node_a.children.add(node_s)
+                node_s.parents.add(node_a)
+                self.s_levels[level].add(node_s)
 
     def update_a_mutex(self, nodeset):
         ''' Determine and update sibling mutual exclusion for A-level nodes
@@ -386,8 +393,8 @@ def inconsistent_effects_mutex(self, node_a1: PgNode_a, node_a2: PgNode_a) -> bo
         :param node_a2: PgNode_a
         :return: bool
         '''
-        # TODO test for Inconsistent Effects between nodes
-        return False
+        return (set(node_a1.action.effect_add) & set(node_a2.action.effect_rem) |
+               set(node_a1.action.effect_rem) & set(node_a2.action.effect_add))
 
     def interference_mutex(self, node_a1: PgNode_a, node_a2: PgNode_a) -> bool:
         '''
@@ -403,8 +410,10 @@ def interference_mutex(self, node_a1: PgNode_a, node_a2: PgNode_a) -> bool:
         :param node_a2: PgNode_a
         :return: bool
         '''
-        # TODO test for Interference between nodes
-        return False
+        return (set(node_a1.action.effect_add) & set(node_a2.action.precond_neg)|
+                set(node_a2.action.effect_add) & set(node_a1.action.precond_neg)|
+                set(node_a1.action.effect_rem) & set(node_a2.action.precond_pos)|
+                set(node_a2.action.effect_rem) & set(node_a1.action.precond_pos))
 
     def competing_needs_mutex(self, node_a1: PgNode_a, node_a2: PgNode_a) -> bool:
         '''
@@ -417,8 +426,18 @@ def competing_needs_mutex(self, node_a1: PgNode_a, node_a2: PgNode_a) -> bool:
         :return: bool
         '''
 
-        # TODO test for Competing Needs between nodes
-        return False
+        a1_precond_mutexes = set()
+        a2_precond_mutexes = set()
+        
+        for item in node_a1.parents: 
+            for m in item.mutex:
+                a1_precond_mutexes.add(m)
+
+        for item in node_a2.parents: 
+            for m in item.mutex:
+                a2_precond_mutexes.add(m)
+            
+        return bool((a1_precond_mutexes & node_a2.parents) | (a2_precond_mutexes & node_a1.parents))
 
     def update_s_mutex(self, nodeset: set):
         ''' Determine and update sibling mutual exclusion for S-level nodes
@@ -452,8 +471,7 @@ def negation_mutex(self, node_s1: PgNode_s, node_s2: PgNode_s) -> bool:
         :param node_s2: PgNode_s
         :return: bool
         '''
-        # TODO test for negation between nodes
-        return False
+        return (node_s1.symbol == node_s2.symbol) and (node_s1.is_pos != node_s2.is_pos)
 
     def inconsistent_support_mutex(self, node_s1: PgNode_s, node_s2: PgNode_s):
         '''
@@ -471,8 +489,16 @@ def inconsistent_support_mutex(self, node_s1: PgNode_s, node_s2: PgNode_s):
         :param node_s2: PgNode_s
         :return: bool
         '''
-        # TODO test for Inconsistent Support between nodes
-        return False
+        mutexes_s1 = set()
+        mutexes_s2 = set()
+        for p in node_s1.parents: 
+            mutexes_s1 |= p.mutex
+
+        for p in node_s2.parents: 
+            mutexes_s2 |= p.mutex
+
+        return (not bool(node_s1.parents - mutexes_s2) or not bool(node_s2.parents - mutexes_s1)) \
+               and not bool(node_s1.parents & node_s2.parents)
 
     def h_levelsum(self) -> int:
         '''The sum of the level costs of the individual goals (admissible if goals independent)
@@ -480,6 +506,9 @@ def h_levelsum(self) -> int:
         :return: int
         '''
         level_sum = 0
-        # TODO implement
-        # for each goal in the problem, determine the level cost, then add them together
+        for goal in self.problem.goal:
+            for level, s_nodes in enumerate(self.s_levels):
+                if PgNode_s(goal, True) in s_nodes:
+                    level_sum += level
+                    break
         return level_sum