diff --git a/rs/context_automaton.py b/rs/context_automaton.py
index f99fb71..68277c3 100644
--- a/rs/context_automaton.py
+++ b/rs/context_automaton.py
@@ -9,7 +9,8 @@ class ContextAutomaton(object):
         self._init_state = None
         self._reaction_system = reaction_system
         self._name = ""
-    
+        self._prod_entities = set()
+        
     @property
     def states(self):
         return self._states
@@ -18,6 +19,14 @@ class ContextAutomaton(object):
     def transitions(self):
         return self._transitions
     
+    @property
+    def prod_entities(self):
+        return self._prod_entities
+    
+    @property
+    def reaction_system(self):
+        return self._reaction_system
+    
     @property
     def name(self):
         return self._name
@@ -101,6 +110,8 @@ class ContextAutomaton(object):
         new_context_set = set()
         for e in set(context_set):
             new_context_set.add(self._reaction_system.get_entity_id(e))
+            
+        self._prod_entities |= new_context_set
         
         self._transitions.append((self.get_state_id(src),new_context_set,self.get_state_id(dst)))
 
@@ -140,8 +151,14 @@ class ContextAutomaton(object):
             name_string = ": " + colour_str(C_BOLD, self.name)
             print(C_MARK_INFO + " Context automaton" + name_string)       
 
+    def show_prod_entities(self):
+        print(C_MARK_INFO + " Context automaton possible products:")
+        for entity in self._prod_entities:
+            print(" - " + self._reaction_system.get_entity_name(entity))
+        
     def show(self):
         self.show_header()
         self.show_states()
         self.show_transitions()
+        self.show_prod_entities()
 
diff --git a/rs/extended_context_automaton.py b/rs/extended_context_automaton.py
index 0fe1757..870226d 100644
--- a/rs/extended_context_automaton.py
+++ b/rs/extended_context_automaton.py
@@ -4,15 +4,52 @@ from colour import *
 from rs.context_automaton import ContextAutomaton
 
 class ExtendedContextAutomaton(ContextAutomaton):
-    """Extended Context Automaton"""
+    """Extended Context Automaton
+    
+    Supports transitions with actions.
+    
+    Each transitions is additionally guarded with
+    reactants and inhibitors.
+    
+    The provided context entities are the products
+    of the reactions labelling the transition taken.
+    """
+
     def __init__(self, reaction_system):
-        self._actions = []
         super(ExtendedContextAutomaton, self).__init__(reaction_system)
+        self._actions = []
+        self._transitions_for_products = dict()
+        self._actions_for_products = dict()
     
     @property
     def number_of_actions(self):
         return len(self._actions)
     
+    @property
+    def actions(self):
+        return self._actions
+        
+    def has_action(self, action):
+        """Checks if the automaton supports a given action"""
+        
+        return action in self._actions
+    
+    def get_transitions_producing_entity(self, entity):
+        """Returns the transitions that produce a given entity"""
+        
+        if entity in self._transitions_for_products:
+            return self._transitions_for_products[entity]
+        else:
+            return []
+    
+    def get_actions_producing_entity(self, entity):
+        """Returns the actions that produce a given entity"""
+        
+        if entity in self._actions_for_products:
+            return self._actions_for_products[entity]
+        else:
+            return set()
+    
     def add_transition(self, src, actions, ctx_reaction, dst):
         """Adds a transition
         
@@ -49,10 +86,21 @@ class ExtendedContextAutomaton(ContextAutomaton):
         i_ids = self.get_set_of_ids(ctx_inhibitors)
         p_ids = self.get_set_of_ids(ctx_products)
         
-        self._transitions.append((src_id, act_ids, (r_ids, i_ids, p_ids), dst_id))
+        new_transition = (src_id, act_ids, (r_ids, i_ids, p_ids), dst_id)
+        
+        for product_id in p_ids:
+            self._transitions_for_products.setdefault(product_id, [])
+            self._transitions_for_products[product_id].append(new_transition)
+            self._actions_for_products.setdefault(product_id, set())
+            self._actions_for_products[product_id] |= set(actions)
+        
+        self._prod_entities |= p_ids
+        
+        self._transitions.append(new_transition)
     
     def show_transitions(self):
         """Prints the set of registered transitions"""
+        
         print(C_MARK_INFO + " Context automaton transitions:")
         for src_id, act_id, reaction, dst_id in self._transitions:
             str_transition = self.get_state_name(src_id) + " --( " 
@@ -63,6 +111,7 @@ class ExtendedContextAutomaton(ContextAutomaton):
     
     def add_action(self, action_name):
         """Registers an action"""
+        
         if action_name not in self._actions:
             self._actions.append(action_name)
         else:
@@ -70,6 +119,7 @@ class ExtendedContextAutomaton(ContextAutomaton):
     
     def get_action_id(self, action_name):
         """For an action name returns its id"""
+        
         try:
             return self._actions.index(action_name)
         except ValueError:
@@ -81,6 +131,7 @@ class ExtendedContextAutomaton(ContextAutomaton):
                 
     def get_set_of_action_ids(self, actions):
         """Converts a set of actions into the set of their ids"""
+        
         act_ids = set()
         for act in actions:
             act_ids.add(self.get_action_id(act))
@@ -88,6 +139,7 @@ class ExtendedContextAutomaton(ContextAutomaton):
         
     def get_actions_str(self, actions):
         """Returns the string for the set of action ids given by actions"""
+        
         s = ""
         for act in actions:
             s += self.get_action_name(act) + ", "
@@ -96,6 +148,7 @@ class ExtendedContextAutomaton(ContextAutomaton):
                         
     def show_actions(self):
         """Prints all the actions"""
+        
         print(C_MARK_INFO + " Context automaton actions:")
         for act in self._actions:
             print(" - " + act + " (id=" + str(self.get_action_id(act)) + ")")
@@ -103,3 +156,4 @@ class ExtendedContextAutomaton(ContextAutomaton):
     def show(self):
         super(ExtendedContextAutomaton, self).show()
         self.show_actions()
+        
diff --git a/rs/network_of_context_automata.py b/rs/network_of_context_automata.py
index 51ab4ea..86b1931 100644
--- a/rs/network_of_context_automata.py
+++ b/rs/network_of_context_automata.py
@@ -1,18 +1,100 @@
 from sys import exit
+from colour import *
 
 class NetworkOfContextAutomata(object):
     
-    def __init__(self, context_automata):
-        self.automata = list(context_automata)
+    def __init__(self, reaction_system, context_automata):
+        self.automata = []
+        self._reaction_system = reaction_system
+        self._actions = set()
+        self._prod_entities = set()
+        self._automata_for_actions = dict()
+        self._actions_for_products = dict()
+
+        if len(context_automata) < 1:
+            print("Context automata network must contain at least one automaton!")
+            exit(1)
+            
+        for automaton in context_automata:
+            self.add(automaton)
+
+        self.sanity_check()
 
     @property
     def number_of_automata(self):
         return len(self.automata)
 
+    @property
+    def reaction_system(self):
+        return self._reaction_system
+
+    @property
+    def prod_entities(self):
+        """Returns the set of entities that can potentially be produced by the automata in the network"""
+        return self._prod_entities
+
+    def sanity_check(self):
+        """Performs a sanity check of the network of automata"""
+        
+        for automaton in self.automata:
+            if automaton.reaction_system != self._reaction_system:
+                print_error("Mismatching reaction system used in \"" + str(automaton.name) + "\"!!!")
+                exit(1)
+
+    def show_prod_entities(self):
+        print(C_MARK_INFO + " Possible context-products for the network of automata:")
+        for entity in self.prod_entities:
+            print(" - " + self._reaction_system.get_entity_name(entity))
+
+    def show_actions(self):
+        print(C_MARK_INFO + " Actions of the network:")
+        for action in self._actions:
+            print(" - " + action)
+
+    def register_action(self, action, aut):
+        """Associates an action with an automaton"""
+        
+        self._automata_for_actions.setdefault(action, set())
+        aut_index = self.automata.index(aut)
+        self._automata_for_actions[action].add(aut_index)
+        
+    def get_actions_producing_entity(self, entity):
+        """Returns the set of actions producing an entity"""
+        
+        if entity in self._actions_for_products:
+            return self._actions_for_products[entity]
+        else:
+            return set()
+            
+    def get_automata_with_action(self, action):
+        """Returns the set of automata that support an action"""
+        
+        if action in self._automata_for_actions:
+            return self._automata_for_actions[action]
+        else:
+            return set()
+
+    def add(self, aut):
+        """Adds an automaton to the network"""
+        
+        self.automata.append(aut)
+        self._prod_entities |= aut.prod_entities
+        self._actions |= set(aut.actions)
+        
+        for action in aut.actions:
+            self.register_action(action, aut)
+
+        for entity in aut.prod_entities:
+            self._actions_for_products.setdefault(entity, set())
+            self._actions_for_products[entity] |= aut.get_actions_producing_entity(entity)
+
     def show(self):
+        print()
+        print(C_MARK_INFO + " NETWORK OF CONTEXT AUTOMATA")
         for ca in self.automata:
             print()
             ca.show()
-
-    def add(self, aut):
-        self.automata.append(aut)
+        print()
+        self.show_prod_entities()
+        self.show_actions()
+        
\ No newline at end of file
diff --git a/rs/reaction_system.py b/rs/reaction_system.py
index 1ea8293..42c8bc9 100644
--- a/rs/reaction_system.py
+++ b/rs/reaction_system.py
@@ -15,6 +15,14 @@ class ReactionSystem(object):
         self.init_contexts = []
         self.context_entities = []
 
+    @property
+    def background_set_size(self):
+        return len(self.background_set)
+        
+    @property
+    def set_of_bgset_ids(self):
+        return set(range(self.background_set_size))
+
     def assume_not_in_bgset(self, name):
         if self.is_in_background_set(name):
             raise RuntimeError("The entity " + name + " is already on the list")
diff --git a/rs_testing.py b/rs_testing.py
index 929e61c..14d21c1 100644
--- a/rs_testing.py
+++ b/rs_testing.py
@@ -12,6 +12,8 @@ def test_extended_automaton():
     r = ReactionSystem()
     r.add_bg_set_entity("inc")
     r.add_bg_set_entity("dec")
+    r.add_bg_set_entity("decx")
+    
 
     c1 = ExtendedContextAutomaton(r)
     c1.add_init_state("init")
@@ -19,19 +21,44 @@ def test_extended_automaton():
     c1.add_state("working")
     c1.add_action("act1")
     c1.add_action("act2")
-    c1.add_transition("init", ["act1", "act2"], ([],[],["inc"]), "working")
+    c1.add_transition("init", ["act1", "act2"], ([],[],["inc","dec"]), "working")
     c1.add_transition("working", ["act2"], ([],[],["inc"]), "working")
 
     c2 = ExtendedContextAutomaton(r)
     c2.add_init_state("init")
-    c2.name = "cxxxx"
+    c2.name = "c2"
     c2.add_state("working")
     c2.add_action("act1")
     c2.add_action("act2")
     c2.add_transition("init", ["act1", "act2"], ([],[],["inc"]), "working")
     c2.add_transition("working", ["act2"], ([],[],["inc"]), "working")
+    
+    c3 = ExtendedContextAutomaton(r)
+    c3.add_init_state("init")
+    c3.name = "c3"
+    c3.add_state("working")
+    c3.add_action("act1")
+    c3.add_transition("init", ["act1"], ([],[],["inc"]), "working")
+    #
+    # c4 = ExtendedContextAutomaton(r)
+    # c4.add_init_state("init")
+    # c4.name = "c4"
+    # c4.add_state("working")
+    # c4.add_action("act1")
+    # c4.add_action("act42")
+    # c4.add_transition("init", ["act1", "act42"], ([],[],["inc"]), "working")
+    # c4.add_transition("working", ["act42"], ([],[],["inc"]), "working")
+    #
+    # c5 = ExtendedContextAutomaton(r)
+    # c5.add_init_state("init")
+    # c5.name = "c5"
+    # c5.add_state("working")
+    # c5.add_action("act1")
+    # c5.add_action("act2")
+    # c5.add_transition("init", ["act1", "act2"], ([],[],["inc"]), "working")
+    # c5.add_transition("working", ["act2"], ([],[],["inc"]), "working")
 
-    na = NetworkOfContextAutomata([c1,c2])
+    na = NetworkOfContextAutomata(r, [c1,c2,c3])
 
     rna = ReactionSystemWithNetworkOfAutomata(r,na)
 
diff --git a/rssmt.py b/rssmt.py
index 735b0ac..d3b9a2d 100755
--- a/rssmt.py
+++ b/rssmt.py
@@ -24,8 +24,8 @@ version = "2016/12/28/00"
 rsmc_banner = """
 Reaction Systems SMT-Based Model Checking
 
-Version: """ + version + """
-Author:  Artur Męski <meski@ipipan.waw.pl> / <artur.meski@ncl.ac.uk>
+Version:  """ + version + """
+Author:   Artur Męski <meski@ipipan.waw.pl> / <artur.meski@ncl.ac.uk>
 """
 
 ##################################################################    
diff --git a/smt/smt_checker_rs_na.py b/smt/smt_checker_rs_na.py
index 55e1ff6..3905eb5 100644
--- a/smt/smt_checker_rs_na.py
+++ b/smt/smt_checker_rs_na.py
@@ -59,45 +59,26 @@ class SmtCheckerRSNA(SmtCheckerRS):
         
     def enc_transition_relation(self, level):
         return simplify(And(self.enc_rs_trans(level), self.enc_automaton_trans(level)))
-    
-    def enc_automaton_single_trans(self, level, transition):
 
-        src,actions,ctx_reaction,dst = transition
-
-        src_enc = self.ca_state[level] == src
-        dst_enc = self.ca_state[level+1] == dst
-
-        all_ent = set(range(len(self.rs.background_set)))
-        incl_ctx = ctx
-        excl_ctx = all_ent - incl_ctx
-
-        ctx_enc = True
-
-        for c in incl_ctx:
-            ctx_enc = simplify(And(ctx_enc, self.v_ctx[level][c]))
-        for c in excl_ctx:
-            ctx_enc = simplify(And(ctx_enc, Not(self.v_ctx[level][c])))
-
-        enc_single_trans = simplify(And(src_enc, ctx_enc, dst_enc))
-
-        return enc_single_trans
-    
-    def enc_single_automaton_trans(self, level, automaton):
-        
-        enc_aut_trans = False
-        for transition in automaton.transitions:
-            enc_aut_trans = simplify(Or(enc_aut_trans, self.enc_automaton_single_trans(level, transition)))
-        
-        return enc_aut_trans
-    
     def enc_automaton_trans(self, level):
         """Encodes the transition relation for the context automaton"""
         
-        enc_canet = True
-        for aut in self.canet:
-            enc_canet = simplify(And(enc_canet, self.enc_single_automaton_trans(level, aut)))
+        enc_trans = True
+                
+        prod_context = self.canet.prod_entities
+        never_produced_context = self.rs.set_of_bgset_ids - prod_context
+        
+        # producible entities:
+        for ent in prod_context:
+            actions_producing_ent = self.canet.get_actions_producing_entity(ent)            
+            for act in actions_producing_ent:
+                automata_with_act = self.canet.get_automata_with_action(act)
+                for aut_id in automata_with_act:
+                    aut = self.canet.automata[aut_id]
 
-        return enc_canet
+        # entities that are never produced:
+        
+        return enc_trans
 
     def check_reachability(self, state, print_witness=True, print_time=True, print_mem=True):
     
@@ -108,4 +89,6 @@ class SmtCheckerRSNA(SmtCheckerRS):
         self.prepare_all_variables()
         self.prepare_all_variables()
         self.prepare_all_variables()
+        
+        print(self.enc_automaton_trans(0))