diff --git a/Implab/AbstractEvent.cs b/Implab/AbstractEvent.cs
--- a/Implab/AbstractEvent.cs
+++ b/Implab/AbstractEvent.cs
@@ -160,8 +160,12 @@ namespace Implab {
 
                 if (slot < RESERVED_HANDLERS_COUNT) {
 
-                    if (slot == 0)
-                        Interlocked.CompareExchange(ref m_handlers, new THandler[RESERVED_HANDLERS_COUNT], null);
+                    if (slot == 0) {
+                        m_handlers = new THandler[RESERVED_HANDLERS_COUNT];
+                    } else {
+                        while (m_handlers == null)
+                            Thread.MemoryBarrier();
+                    }
 
                     m_handlers[slot] = handler;
 
diff --git a/Implab/Parsing/CDFADefinition.cs b/Implab/Parsing/CDFADefinition.cs
--- a/Implab/Parsing/CDFADefinition.cs
+++ b/Implab/Parsing/CDFADefinition.cs
@@ -11,10 +11,8 @@
         }
 
         public CDFADefinition Optimize() {
-            var optimized = new CDFADefinition(new CharAlphabet());
-
-            Optimize(optimized, m_alphabet, optimized.Alphabet);
-            return optimized;
+            
+            return (CDFADefinition)Optimize(alphabet => new CDFADefinition((CharAlphabet)alphabet), m_alphabet, new CharAlphabet());
         }
 
         public void PrintDFA() {
diff --git a/Implab/Parsing/DFADefinition.cs b/Implab/Parsing/DFADefinition.cs
--- a/Implab/Parsing/DFADefinition.cs
+++ b/Implab/Parsing/DFADefinition.cs
@@ -66,8 +66,8 @@ namespace Implab.Parsing {
             m_states[s1].transitions[symbol] = s2;
         }
 
-        public void Optimize<TA>(IDFADefinition minimalDFA,IAlphabet<TA> sourceAlphabet, IAlphabet<TA> minimalAlphabet) {
-            Safe.ArgumentNotNull(minimalDFA, "minimalDFA");
+        protected IDFADefinition Optimize<TA>(Func<IAlphabet<TA>, IDFADefinition> dfaFactory,IAlphabet<TA> sourceAlphabet, IAlphabet<TA> minimalAlphabet) {
+            Safe.ArgumentNotNull(dfaFactory, "dfaFactory");
             Safe.ArgumentNotNull(minimalAlphabet, "minimalAlphabet");
 
             var setComparer = new CustomEqualityComparer<HashSet<int>>(
@@ -211,6 +211,8 @@ namespace Implab.Parsing {
             
             // построение автомата
 
+            var minimalDFA = dfaFactory(minimalAlphabet);
+
             var states = new int[ optimalMap.Length ];
             states[0] = UNREACHEBLE_STATE;
             
@@ -237,6 +239,7 @@ namespace Implab.Parsing {
                 }
             }
 
+            return minimalDFA;
         }
 
         public void PrintDFA<TA>(IAlphabet<TA> alphabet) {
diff --git a/Implab/Parsing/EDFADefinition.cs b/Implab/Parsing/EDFADefinition.cs
--- a/Implab/Parsing/EDFADefinition.cs
+++ b/Implab/Parsing/EDFADefinition.cs
@@ -18,10 +18,8 @@ namespace Implab.Parsing {
         }
 
         public EDFADefinition<T> Optimize() {
-            var optimized = new EDFADefinition<T>(new EnumAlphabet<T>());
-            Optimize(optimized, m_alphabet, optimized.Alphabet);
-
-            return optimized;
+            
+            return (EDFADefinition<T>)Optimize(alphabet => new EDFADefinition<T>((EnumAlphabet<T>)alphabet), m_alphabet, new EnumAlphabet<T>());
         }
 
         public void PrintDFA() {