--- a/Implab/Automaton/MapAlphabet.cs	Thu Mar 10 01:19:33 2016 +0300
+++ b/Implab/Automaton/MapAlphabet.cs	Mon Mar 14 01:19:38 2016 +0300
@@ -38,7 +38,6 @@
             Safe.ArgumentNotNull(symbols, "symbols");
 
             m_nextCls = Math.Max(cls + 1, m_nextCls);
-            symbols = symbols.Distinct();
 
             foreach (var symbol in symbols)
                 m_map[symbol] = cls;
@@ -68,6 +67,10 @@
             return m_supportUnclassified || m_map.ContainsKey(symbol);
         }
 
+
+        public IEnumerable<T> GetSymbols(int cls) {
+            return m_map.Where(p => p.Value == cls).Select(p => p.Key);
+        }
         #endregion
     }
 }