Index: branches/SymbolicExpressionTreeDiversityAnalyzers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Analyzers/SymbolicDataAnalysisBottomUpDiversityAnalyzer.cs
===================================================================
--- branches/SymbolicExpressionTreeDiversityAnalyzers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Analyzers/SymbolicDataAnalysisBottomUpDiversityAnalyzer.cs	(revision 12029)
+++ branches/SymbolicExpressionTreeDiversityAnalyzers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Analyzers/SymbolicDataAnalysisBottomUpDiversityAnalyzer.cs	(revision 12029)
@@ -0,0 +1,46 @@
+﻿#region License Information
+/* HeuristicLab
+ * Copyright (C) 2002-2015 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 HeuristicLab.Analysis;
+using HeuristicLab.Common;
+using HeuristicLab.Core;
+using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
+
+namespace HeuristicLab.Problems.DataAnalysis.Symbolic.Analyzers {
+  [Item("SymbolicDataAnalysisBottomUpDiversityAnalyzer", "A diversity analyzer based on the bottom-up distance between trees.")]
+  [StorableClass]
+  public class SymbolicDataAnalysisBottomUpDiversityAnalyzer : SingleObjectivePopulationDiversityAnalyzer {
+    [StorableConstructor]
+    protected SymbolicDataAnalysisBottomUpDiversityAnalyzer(bool deserializing) : base(deserializing) { }
+
+    private SymbolicDataAnalysisBottomUpDiversityAnalyzer(SymbolicDataAnalysisBottomUpDiversityAnalyzer original, Cloner cloner)
+      : base(original, cloner) {
+    }
+
+    public override IDeepCloneable Clone(Cloner cloner) {
+      return new SymbolicDataAnalysisBottomUpDiversityAnalyzer(this, cloner);
+    }
+
+    public SymbolicDataAnalysisBottomUpDiversityAnalyzer() {
+      SimilarityCalculator = new SymbolicExpressionTreeBottomUpSimilarityCalculator { SolutionVariableName = "SymbolicExpressionTree" };
+    }
+  }
+}
Index: branches/SymbolicExpressionTreeDiversityAnalyzers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/HeuristicLab.Problems.DataAnalysis.Symbolic-3.4.csproj
===================================================================
--- branches/SymbolicExpressionTreeDiversityAnalyzers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/HeuristicLab.Problems.DataAnalysis.Symbolic-3.4.csproj	(revision 12028)
+++ branches/SymbolicExpressionTreeDiversityAnalyzers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/HeuristicLab.Problems.DataAnalysis.Symbolic-3.4.csproj	(revision 12029)
@@ -41,5 +41,5 @@
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
-    <OutputPath>$(SolutionDir)\bin\</OutputPath>
+    <OutputPath>..\..\..\..\trunk\sources\bin\</OutputPath>
     <DefineConstants>DEBUG;TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
@@ -51,5 +51,5 @@
     <DebugType>pdbonly</DebugType>
     <Optimize>true</Optimize>
-    <OutputPath>$(SolutionDir)\bin\</OutputPath>
+    <OutputPath>..\..\..\..\trunk\sources\bin\</OutputPath>
     <DefineConstants>TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
@@ -60,5 +60,5 @@
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|x64' ">
     <DebugSymbols>true</DebugSymbols>
-    <OutputPath>$(SolutionDir)\bin\</OutputPath>
+    <OutputPath>..\..\..\..\trunk\sources\bin\</OutputPath>
     <DefineConstants>DEBUG;TRACE</DefineConstants>
     <DebugType>full</DebugType>
@@ -69,5 +69,5 @@
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x64' ">
-    <OutputPath>$(SolutionDir)\bin\</OutputPath>
+    <OutputPath>..\..\..\..\trunk\sources\bin\</OutputPath>
     <DefineConstants>TRACE</DefineConstants>
     <Optimize>true</Optimize>
@@ -80,5 +80,5 @@
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|x86' ">
     <DebugSymbols>true</DebugSymbols>
-    <OutputPath>$(SolutionDir)\bin\</OutputPath>
+    <OutputPath>..\..\..\..\trunk\sources\bin\</OutputPath>
     <DefineConstants>DEBUG;TRACE</DefineConstants>
     <DebugType>full</DebugType>
@@ -89,5 +89,5 @@
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x86' ">
-    <OutputPath>$(SolutionDir)\bin\</OutputPath>
+    <OutputPath>..\..\..\..\trunk\sources\bin\</OutputPath>
     <DefineConstants>TRACE</DefineConstants>
     <Optimize>true</Optimize>
@@ -99,6 +99,70 @@
   </PropertyGroup>
   <ItemGroup>
-    <Reference Include="ALGLIB-3.7.0, Version=3.7.0.0, Culture=neutral, PublicKeyToken=ba48961d6f65dcec, processorArchitecture=MSIL">
-      <HintPath>..\..\bin\ALGLIB-3.7.0.dll</HintPath>
+    <Reference Include="ALGLIB-3.7.0">
+      <HintPath>..\..\..\..\trunk\sources\bin\ALGLIB-3.7.0.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Analysis-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Analysis-3.3.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Collections-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Collections-3.3.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Common-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Common-3.3.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Common.Resources-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Common.Resources-3.3.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Core-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Core-3.3.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Data-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Data-3.3.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Encodings.SymbolicExpressionTreeEncoding-3.4">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Encodings.SymbolicExpressionTreeEncoding-3.4.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Operators-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Operators-3.3.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Optimization-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Optimization-3.3.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Optimization.Operators-3.3, Version=3.3.0.0, Culture=neutral, PublicKeyToken=ba48961d6f65dcec, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Optimization.Operators-3.3.dll</HintPath>
+    </Reference>
+    <Reference Include="HeuristicLab.Parameters-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Parameters-3.3.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Persistence-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Persistence-3.3.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.PluginInfrastructure-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.PluginInfrastructure-3.3.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Problems.DataAnalysis-3.4">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Problems.DataAnalysis-3.4.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Problems.Instances-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Problems.Instances-3.3.dll</HintPath>
+      <Private>False</Private>
+    </Reference>
+    <Reference Include="HeuristicLab.Random-3.3">
+      <HintPath>..\..\..\..\trunk\sources\bin\HeuristicLab.Random-3.3.dll</HintPath>
       <Private>False</Private>
     </Reference>
@@ -118,4 +182,5 @@
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Analyzers\SymbolicDataAnalysisBottomUpDiversityAnalyzer.cs" />
     <Compile Include="Analyzers\SymbolicDataAnalysisSingleObjectivePruningAnalyzer.cs" />
     <Compile Include="Analyzers\SymbolicDataAnalysisSingleObjectiveValidationParetoBestSolutionAnalyzer.cs" />
@@ -240,4 +305,5 @@
     <Compile Include="TreeMatching\SymbolicExpressionTreeNodeComparer.cs" />
     <Compile Include="TreeMatching\SymbolicExpressionTreeNodeEqualityComparer.cs" />
+    <Compile Include="TreeMatching\SymbolicExpressionTreePhenotypicSimilarityCalculator.cs" />
     <None Include="HeuristicLab.snk" />
     <None Include="Plugin.cs.frame" />
@@ -273,85 +339,4 @@
     </BootstrapperPackage>
   </ItemGroup>
-  <ItemGroup>
-    <ProjectReference Include="..\..\HeuristicLab.Analysis\3.3\HeuristicLab.Analysis-3.3.csproj">
-      <Project>{887425B4-4348-49ED-A457-B7D2C26DDBF9}</Project>
-      <Name>HeuristicLab.Analysis-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Collections\3.3\HeuristicLab.Collections-3.3.csproj">
-      <Project>{958B43BC-CC5C-4FA2-8628-2B3B01D890B6}</Project>
-      <Name>HeuristicLab.Collections-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Common.Resources\3.3\HeuristicLab.Common.Resources-3.3.csproj">
-      <Project>{0E27A536-1C4A-4624-A65E-DC4F4F23E3E1}</Project>
-      <Name>HeuristicLab.Common.Resources-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Common\3.3\HeuristicLab.Common-3.3.csproj">
-      <Project>{A9AD58B9-3EF9-4CC1-97E5-8D909039FF5C}</Project>
-      <Name>HeuristicLab.Common-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Core\3.3\HeuristicLab.Core-3.3.csproj">
-      <Project>{C36BD924-A541-4A00-AFA8-41701378DDC5}</Project>
-      <Name>HeuristicLab.Core-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Data\3.3\HeuristicLab.Data-3.3.csproj">
-      <Project>{BBAB9DF5-5EF3-4BA8-ADE9-B36E82114937}</Project>
-      <Name>HeuristicLab.Data-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Encodings.SymbolicExpressionTreeEncoding\3.4\HeuristicLab.Encodings.SymbolicExpressionTreeEncoding-3.4.csproj">
-      <Project>{06D4A186-9319-48A0-BADE-A2058D462EEA}</Project>
-      <Name>HeuristicLab.Encodings.SymbolicExpressionTreeEncoding-3.4</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Operators\3.3\HeuristicLab.Operators-3.3.csproj">
-      <Project>{23DA7FF4-D5B8-41B6-AA96-F0561D24F3EE}</Project>
-      <Name>HeuristicLab.Operators-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Optimization.Operators\3.3\HeuristicLab.Optimization.Operators-3.3.csproj">
-      <Project>{25087811-F74C-4128-BC86-8324271DA13E}</Project>
-      <Name>HeuristicLab.Optimization.Operators-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Optimization\3.3\HeuristicLab.Optimization-3.3.csproj">
-      <Project>{14AB8D24-25BC-400C-A846-4627AA945192}</Project>
-      <Name>HeuristicLab.Optimization-3.3</Name>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Parameters\3.3\HeuristicLab.Parameters-3.3.csproj">
-      <Project>{56F9106A-079F-4C61-92F6-86A84C2D84B7}</Project>
-      <Name>HeuristicLab.Parameters-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Persistence\3.3\HeuristicLab.Persistence-3.3.csproj">
-      <Project>{102BC7D3-0EF9-439C-8F6D-96FF0FDB8E1B}</Project>
-      <Name>HeuristicLab.Persistence-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.PluginInfrastructure\3.3\HeuristicLab.PluginInfrastructure-3.3.csproj">
-      <Project>{94186A6A-5176-4402-AE83-886557B53CCA}</Project>
-      <Name>HeuristicLab.PluginInfrastructure-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Problems.DataAnalysis\3.4\HeuristicLab.Problems.DataAnalysis-3.4.csproj">
-      <Project>{DF87C13E-A889-46FF-8153-66DCAA8C5674}</Project>
-      <Name>HeuristicLab.Problems.DataAnalysis-3.4</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Problems.Instances\3.3\HeuristicLab.Problems.Instances-3.3.csproj">
-      <Project>{3540E29E-4793-49E7-8EE2-FEA7F61C3994}</Project>
-      <Name>HeuristicLab.Problems.Instances-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-    <ProjectReference Include="..\..\HeuristicLab.Random\3.3\HeuristicLab.Random-3.3.csproj">
-      <Project>{F4539FB6-4708-40C9-BE64-0A1390AEA197}</Project>
-      <Name>HeuristicLab.Random-3.3</Name>
-      <Private>False</Private>
-    </ProjectReference>
-  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
Index: branches/SymbolicExpressionTreeDiversityAnalyzers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/SymbolicDataAnalysisProblem.cs
===================================================================
--- branches/SymbolicExpressionTreeDiversityAnalyzers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/SymbolicDataAnalysisProblem.cs	(revision 12028)
+++ branches/SymbolicExpressionTreeDiversityAnalyzers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/SymbolicDataAnalysisProblem.cs	(revision 12029)
@@ -23,5 +23,4 @@
 using System.Drawing;
 using System.Linq;
-using HeuristicLab.Analysis;
 using HeuristicLab.Common;
 using HeuristicLab.Common.Resources;
@@ -30,8 +29,8 @@
 using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
 using HeuristicLab.Optimization;
-using HeuristicLab.Optimization.Operators;
 using HeuristicLab.Parameters;
 using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
 using HeuristicLab.PluginInfrastructure;
+using HeuristicLab.Problems.DataAnalysis.Symbolic.Analyzers;
 using HeuristicLab.Problems.Instances;
 
@@ -233,5 +232,6 @@
       Operators.Add(new MinAverageMaxSymbolicExpressionTreeLengthAnalyzer());
       Operators.Add(new SymbolicExpressionTreeLengthAnalyzer());
-      Operators.Add(new SingleObjectivePopulationDiversityAnalyzer());
+      Operators.Add(new SymbolicDataAnalysisBottomUpDiversityAnalyzer());
+      Operators.Add(new SymbolicDataAnalysisPhenotypicDiversityAnalyzer());
       ParameterizeOperators();
     }
@@ -353,10 +353,15 @@
         op.EvaluatorParameter.ActualName = EvaluatorParameter.Name;
       }
-      foreach (var op in operators.OfType<SingleObjectiveSolutionSimilarityCalculator>()) {
-        op.QualityVariableName = "Quality";
-        op.SolutionVariableName = SolutionCreator.SymbolicExpressionTreeParameter.ActualName;
-      }
-      foreach (var op in operators.OfType<SingleObjectivePopulationDiversityAnalyzer>()) {
-        op.SimilarityCalculator = new SymbolicExpressionTreeBottomUpSimilarityCalculator();
+      foreach (var op in operators.OfType<SymbolicDataAnalysisBottomUpDiversityAnalyzer>()) {
+        var similarityCalculator = new SymbolicExpressionTreeBottomUpSimilarityCalculator();
+        similarityCalculator.QualityVariableName = "Quality";
+        similarityCalculator.SolutionVariableName = SolutionCreator.SymbolicExpressionTreeParameter.ActualName;
+        op.SimilarityCalculator = similarityCalculator;
+      }
+      foreach (var op in operators.OfType<SymbolicDataAnalysisPhenotypicDiversityAnalyzer>()) {
+        var similarityCalculator = new SymbolicExpressionTreePhenotypicSimilarityCalculator();
+        similarityCalculator.QualityVariableName = "Quality";
+        similarityCalculator.SolutionVariableName = SolutionCreator.SymbolicExpressionTreeParameter.ActualName;
+        op.SimilarityCalculator = similarityCalculator;
       }
     }
Index: branches/SymbolicExpressionTreeDiversityAnalyzers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/TreeMatching/SymbolicExpressionTreePhenotypicSimilarityCalculator.cs
===================================================================
--- branches/SymbolicExpressionTreeDiversityAnalyzers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/TreeMatching/SymbolicExpressionTreePhenotypicSimilarityCalculator.cs	(revision 12029)
+++ branches/SymbolicExpressionTreeDiversityAnalyzers/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/TreeMatching/SymbolicExpressionTreePhenotypicSimilarityCalculator.cs	(revision 12029)
@@ -0,0 +1,76 @@
+﻿#region License Information
+/* HeuristicLab
+ * Copyright (C) 2002-2014 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 HeuristicLab.Common;
+using HeuristicLab.Core;
+using HeuristicLab.Data;
+using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
+using HeuristicLab.Optimization.Operators;
+using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
+
+namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
+  [Item("SymbolicExpressionTreePhenotypicSimilarityCalculator", "An operator that calculates the similarity betweeon two trees based on the correlation of their outputs.")]
+  [StorableClass]
+  public class SymbolicExpressionTreePhenotypicSimilarityCalculator : SingleObjectiveSolutionSimilarityCalculator {
+    public IDataAnalysisProblemData ProblemData { get; set; }
+    public ISymbolicDataAnalysisExpressionTreeInterpreter Interpreter { get; set; }
+
+    [StorableConstructor]
+    protected SymbolicExpressionTreePhenotypicSimilarityCalculator(bool deserializing) : base(deserializing) { }
+
+    public SymbolicExpressionTreePhenotypicSimilarityCalculator(SymbolicExpressionTreePhenotypicSimilarityCalculator original, Cloner cloner)
+      : base(original, cloner) {
+      this.ProblemData = original.ProblemData;
+      this.Interpreter = original.Interpreter;
+    }
+
+    public override IDeepCloneable Clone(Cloner cloner) {
+      return new SymbolicExpressionTreePhenotypicSimilarityCalculator(this, cloner);
+    }
+
+    public SymbolicExpressionTreePhenotypicSimilarityCalculator() { }
+
+    public double CalculateSimilarity(ISymbolicExpressionTree t1, ISymbolicExpressionTree t2) {
+      var v1 = Interpreter.GetSymbolicExpressionTreeValues(t1, ProblemData.Dataset, ProblemData.TrainingIndices);
+      var v2 = Interpreter.GetSymbolicExpressionTreeValues(t2, ProblemData.Dataset, ProblemData.TrainingIndices);
+
+      OnlineCalculatorError error;
+      var r2 = OnlinePearsonsRSquaredCalculator.Calculate(v1, v2, out error);
+
+      if (r2 > 1.0)
+        r2 = 1.0;
+
+      return error == OnlineCalculatorError.None ? r2 : 0;
+    }
+
+    public override double CalculateSolutionSimilarity(IScope leftSolution, IScope rightSolution) {
+      var leftValues = (DoubleArray)leftSolution.Variables["EstimatedValues"].Value;
+      var rightValues = (DoubleArray)rightSolution.Variables["EstimatedValues"].Value;
+      OnlineCalculatorError error;
+      var r2 = OnlinePearsonsRSquaredCalculator.Calculate(leftValues, rightValues, out error);
+
+      if (r2 > 1.0)
+        r2 = 1.0; // sometimes due to fp errors it can happen that the r2 is over 1 (like 1.0000000009)
+
+      return error == OnlineCalculatorError.None ? r2 : 0;
+    }
+  }
+}
