Index: branches/SlaveShutdown/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/HeuristicLab.Problems.DataAnalysis.Symbolic-3.4.csproj
===================================================================
--- branches/SlaveShutdown/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/HeuristicLab.Problems.DataAnalysis.Symbolic-3.4.csproj	(revision 8944)
+++ branches/SlaveShutdown/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/HeuristicLab.Problems.DataAnalysis.Symbolic-3.4.csproj	(revision 8954)
@@ -140,4 +140,5 @@
     <Compile Include="Crossovers\SymbolicDataAnalysisExpressionSemanticSimilarityCrossover.cs" />
     <Compile Include="Interfaces\ISymbolicDataAnalysisExpressionCrossover.cs" />
+    <Compile Include="Interfaces\ISymbolicDataAnalysisImpactValuesCalculator.cs" />
     <Compile Include="Interpreter\InterpreterState.cs" />
     <Compile Include="Interpreter\OpCodes.cs" />
@@ -164,4 +165,5 @@
     <Compile Include="SymbolicDataAnalysisExpressionTreeSimplifier.cs" />
     <Compile Include="SymbolicDataAnalysisProblem.cs" />
+    <Compile Include="SymbolicDataAnalysisSolutionImpactValuesCalculator.cs" />
     <Compile Include="Symbols\Addition.cs" />
     <Compile Include="Symbols\And.cs" />
Index: branches/SlaveShutdown/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Interfaces/ISymbolicDataAnalysisImpactValuesCalculator.cs
===================================================================
--- branches/SlaveShutdown/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Interfaces/ISymbolicDataAnalysisImpactValuesCalculator.cs	(revision 8954)
+++ branches/SlaveShutdown/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Interfaces/ISymbolicDataAnalysisImpactValuesCalculator.cs	(revision 8954)
@@ -0,0 +1,9 @@
+﻿using System.Collections.Generic;
+using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
+
+namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
+  public interface ISymbolicDataAnalysisSolutionImpactValuesCalculator {
+    double CalculateReplacementValue(ISymbolicDataAnalysisModel model, ISymbolicExpressionTreeNode node, IDataAnalysisProblemData problemData, IEnumerable<int> rows);
+    double CalculateImpactValue(ISymbolicDataAnalysisModel model, ISymbolicExpressionTreeNode node, IDataAnalysisProblemData problemData, IEnumerable<int> rows, double originalQuality = double.NaN);
+  }
+}
Index: branches/SlaveShutdown/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/SymbolicDataAnalysisSolutionImpactValuesCalculator.cs
===================================================================
--- branches/SlaveShutdown/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/SymbolicDataAnalysisSolutionImpactValuesCalculator.cs	(revision 8954)
+++ branches/SlaveShutdown/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/SymbolicDataAnalysisSolutionImpactValuesCalculator.cs	(revision 8954)
@@ -0,0 +1,50 @@
+﻿#region License Information
+/* HeuristicLab
+ * Copyright (C) 2002-2012 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
+ *
+ * This file is part of HeuristicLab.
+ *
+ * HeuristicLab is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * HeuristicLab is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
+ */
+#endregion
+
+using System.Collections.Generic;
+using HeuristicLab.Common;
+using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
+
+namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
+  public abstract class SymbolicDataAnalysisSolutionImpactValuesCalculator : ISymbolicDataAnalysisSolutionImpactValuesCalculator {
+    public abstract double CalculateReplacementValue(ISymbolicDataAnalysisModel model, ISymbolicExpressionTreeNode node, IDataAnalysisProblemData problemData, IEnumerable<int> rows);
+    public abstract double CalculateImpactValue(ISymbolicDataAnalysisModel model, ISymbolicExpressionTreeNode node, IDataAnalysisProblemData problemData, IEnumerable<int> rows, double originalQuality = double.NaN);
+
+    protected static double CalculateReplacementValue(ISymbolicExpressionTreeNode node, ISymbolicExpressionTree sourceTree, ISymbolicDataAnalysisExpressionTreeInterpreter interpreter,
+      Dataset dataset, IEnumerable<int> rows) {
+      //optimization: constant nodes return always the same value
+      ConstantTreeNode constantNode = node as ConstantTreeNode;
+      if (constantNode != null) return constantNode.Value;
+
+      var rootSymbol = new ProgramRootSymbol().CreateTreeNode();
+      var startSymbol = new StartSymbol().CreateTreeNode();
+      rootSymbol.AddSubtree(startSymbol);
+      startSymbol.AddSubtree((ISymbolicExpressionTreeNode)node.Clone());
+
+      var tempTree = new SymbolicExpressionTree(rootSymbol);
+      // clone ADFs of source tree
+      for (int i = 1; i < sourceTree.Root.SubtreeCount; i++) {
+        tempTree.Root.AddSubtree((ISymbolicExpressionTreeNode)sourceTree.Root.GetSubtree(i).Clone());
+      }
+      return interpreter.GetSymbolicExpressionTreeValues(tempTree, dataset, rows).Median();
+    }
+  }
+}
