Added Clause interfaces to interface.otter

Author: ShobhitLamba

aima-csharp/aima-csharp.csproj

@@ -115,6 +115,9 @@
     <Compile Include="logic\fol\domain\FOLDomainListener.cs" />
     <Compile Include="logic\fol\domain\FOLDomainSkolemConstantAddedEvent.cs" />
     <Compile Include="logic\fol\domain\FOLDomainSkolemFunctionAddedEvent.cs" />
+    <Compile Include="logic\fol\inference\ClauseFilter.cs" />
+    <Compile Include="logic\fol\inference\ClauseSimplifier.cs" />
+    <Compile Include="logic\fol\inference\LightestClauseHeuristic.cs" />
     <Compile Include="logic\fol\kb\data\Chain.cs" />
     <Compile Include="logic\fol\kb\data\Clause.cs" />
     <Compile Include="logic\fol\kb\data\CNF.cs" />

aima-csharp/logic/fol/inference/ClauseFilter.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using aima.core.logic.fol.kb.data;
+
+namespace aima.core.logic.fol.inference.otter
+{
+    /**
+     * @author Ciaran O'Reilly
+     * 
+     */
+    public interface ClauseFilter
+    {
+	HashSet<Clause> filter(HashSet<Clause> clauses);
+    }
+}

aima-csharp/logic/fol/inference/ClauseSimplifier.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using aima.core.logic.fol.kb.data;
+
+namespace aima.core.logic.fol.inference.otter
+{
+    /**
+     * @author Ciaran O'Reilly
+     * 
+     */
+    public interface ClauseSimplifier
+    {
+	Clause simplify(Clause c);
+    }
+}

aima-csharp/logic/fol/inference/LightestClauseHeuristic.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Collections.Generic;
+using aima.core.logic.fol.kb.data;
+
+namespace aima.core.logic.fol.inference.otter
+{
+    /**
+     * Heuristic for selecting lightest clause from SOS. To avoid recalculating the
+     * lightest clause on every call, the interface supports defining the initial
+     * sos and updates to that set so that it can maintain its own internal data
+     * structures to allow for incremental re-calculation of the lightest clause.
+     * 
+     * @author Ciaran O'Reilly
+     * 
+     */
+    public interface LightestClauseHeuristic
+    {
+	/**
+	 * Get the lightest clause from the SOS
+	 * 
+	 * @return the lightest clause.
+	 */
+	Clause getLightestClause();
+
+	/**
+	 * SOS life-cycle methods allowing implementations of this interface to
+	 * incrementally update the calculation of the lightest clause as opposed to
+	 * having to recalculate each time.
+	 * 
+	 * @param clauses
+	 */
+	void initialSOS(HashSet<Clause> clauses);
+
+	void addedClauseToSOS(Clause clause);
+
+	void removedClauseFromSOS(Clause clause);
+    }
+}