From 528e94966e98b1ae66e1254df4a3d77d544ca39c Mon Sep 17 00:00:00 2001
From: Andrea Cavalli <andrea@warp.ovh>
Date: Wed, 7 Feb 2018 22:06:40 +0100
Subject: [PATCH] Added more rules

---
 .../gui/expression/blocks/BlockChar.java      |   1 +
 .../gui/expression/blocks/BlockUndefined.java |  62 +++++++++++
 .../warp/picalculator/math/MathSolver.java    |  59 +++++-----
 .../math/MathematicalSymbols.java             |   3 +-
 .../math/functions/Undefined.java             |  15 ++-
 .../math/rules/FractionsRule12.java           |  49 ---------
 .../math/rules/FractionsRule14.java           |  84 --------------
 .../picalculator/math/rules/NumberRule1.java  |  44 --------
 .../picalculator/math/rules/NumberRule2.java  |  63 -----------
 .../picalculator/math/rules/NumberRule3.java  |  60 ----------
 .../picalculator/math/rules/NumberRule4.java  |  37 -------
 .../picalculator/math/rules/NumberRule5.java  |  46 --------
 .../picalculator/math/rules/NumberRule7.java  |  33 ------
 .../picalculator/math/rules/RuleType.java     |  17 ++-
 .../picalculator/math/rules/RulesManager.java |   2 +-
 .../math/rules/UndefinedRule1.java            |  37 -------
 .../math/rules/UndefinedRule2.java            |  40 -------
 .../math/rules/VariableRule1.java             |  63 -----------
 .../math/rules/VariableRule2.java             |  52 ---------
 .../math/rules/VariableRule3.java             |  53 ---------
 src/main/resources/rules.csv                  |  13 +++
 src/main/resources/rules/FractionsRule12.js   |  68 ++++++++++++
 src/main/resources/rules/FractionsRule14.js   | 104 ++++++++++++++++++
 src/main/resources/rules/NumberRule1.js       |  64 +++++++++++
 src/main/resources/rules/NumberRule2.js       |  83 ++++++++++++++
 src/main/resources/rules/NumberRule3.js       |  80 ++++++++++++++
 src/main/resources/rules/NumberRule4.js       |  55 +++++++++
 src/main/resources/rules/NumberRule5.js       |  71 ++++++++++++
 src/main/resources/rules/NumberRule7.js       |  54 +++++++++
 src/main/resources/rules/UndefinedRule1.js    |  57 ++++++++++
 src/main/resources/rules/UndefinedRule2.js    |  60 ++++++++++
 src/main/resources/rules/VariableRule1.js     |  83 ++++++++++++++
 src/main/resources/rules/VariableRule2.js     |  72 ++++++++++++
 src/main/resources/rules/VariableRule3.js     |  73 ++++++++++++
 34 files changed, 1064 insertions(+), 693 deletions(-)
 create mode 100644 src/main/java/org/warp/picalculator/gui/expression/blocks/BlockUndefined.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/FractionsRule12.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/FractionsRule14.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/NumberRule1.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/NumberRule2.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/NumberRule3.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/NumberRule4.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/NumberRule5.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/NumberRule7.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/UndefinedRule1.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/UndefinedRule2.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/VariableRule1.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/VariableRule2.java
 delete mode 100755 src/main/java/org/warp/picalculator/math/rules/VariableRule3.java
 create mode 100644 src/main/resources/rules/FractionsRule12.js
 create mode 100644 src/main/resources/rules/FractionsRule14.js
 create mode 100644 src/main/resources/rules/NumberRule1.js
 create mode 100644 src/main/resources/rules/NumberRule2.js
 create mode 100644 src/main/resources/rules/NumberRule3.js
 create mode 100644 src/main/resources/rules/NumberRule4.js
 create mode 100644 src/main/resources/rules/NumberRule5.js
 create mode 100644 src/main/resources/rules/NumberRule7.js
 create mode 100644 src/main/resources/rules/UndefinedRule1.js
 create mode 100644 src/main/resources/rules/UndefinedRule2.js
 create mode 100644 src/main/resources/rules/VariableRule1.js
 create mode 100644 src/main/resources/rules/VariableRule2.js
 create mode 100644 src/main/resources/rules/VariableRule3.js

diff --git a/src/main/java/org/warp/picalculator/gui/expression/blocks/BlockChar.java b/src/main/java/org/warp/picalculator/gui/expression/blocks/BlockChar.java
index 664eaa88..74cbb049 100755
--- a/src/main/java/org/warp/picalculator/gui/expression/blocks/BlockChar.java
+++ b/src/main/java/org/warp/picalculator/gui/expression/blocks/BlockChar.java
@@ -4,6 +4,7 @@ import org.warp.picalculator.gui.expression.Caret;
 import org.warp.picalculator.gui.graphicengine.GraphicEngine;
 import org.warp.picalculator.gui.graphicengine.Renderer;
 import org.warp.picalculator.math.MathContext;
+import org.warp.picalculator.math.MathematicalSymbols;
 import org.warp.picalculator.math.parser.features.FeatureChar;
 import org.warp.picalculator.math.parser.features.interfaces.Feature;
 
diff --git a/src/main/java/org/warp/picalculator/gui/expression/blocks/BlockUndefined.java b/src/main/java/org/warp/picalculator/gui/expression/blocks/BlockUndefined.java
new file mode 100644
index 00000000..fd2dde36
--- /dev/null
+++ b/src/main/java/org/warp/picalculator/gui/expression/blocks/BlockUndefined.java
@@ -0,0 +1,62 @@
+package org.warp.picalculator.gui.expression.blocks;
+
+import org.warp.picalculator.gui.expression.Caret;
+import org.warp.picalculator.gui.graphicengine.GraphicEngine;
+import org.warp.picalculator.gui.graphicengine.Renderer;
+import org.warp.picalculator.math.MathContext;
+import org.warp.picalculator.math.MathematicalSymbols;
+import org.warp.picalculator.math.parser.features.FeatureChar;
+import org.warp.picalculator.math.parser.features.interfaces.Feature;
+
+public class BlockUndefined extends Block {
+
+	public BlockUndefined() {
+		recomputeDimensions();
+	}
+
+	@Override
+	public void draw(GraphicEngine ge, Renderer r, int x, int y, Caret caret) {
+		BlockContainer.getDefaultFont(small).use(ge);
+		r.glColor(BlockContainer.getDefaultColor());
+		r.glDrawStringLeft(x, y, "UNDEFINED");
+	}
+
+	@Override
+	public boolean putBlock(Caret caret, Block newBlock) {
+		return false;
+	}
+
+	@Override
+	public boolean delBlock(Caret caret) {
+		return false;
+	}
+
+	@Override
+	public Block getBlock(Caret caret) {
+		return null;
+	}
+
+	@Override
+	public void recomputeDimensions() {
+		width = BlockContainer.getDefaultFont(small).getStringWidth("UNDEFINED");
+		height = BlockContainer.getDefaultCharHeight(small);
+		line = height / 2;
+	}
+
+	@Override
+	public void setSmall(boolean small) {
+		this.small = small;
+		recomputeDimensions();
+	}
+
+	@Override
+	public int computeCaretMaxBound() {
+		return 0;
+	}
+
+	@Override
+	public Feature toFeature(MathContext context) {
+		return new FeatureChar(MathematicalSymbols.UNDEFINED);
+	}
+
+}
diff --git a/src/main/java/org/warp/picalculator/math/MathSolver.java b/src/main/java/org/warp/picalculator/math/MathSolver.java
index 33edb497..76e17874 100644
--- a/src/main/java/org/warp/picalculator/math/MathSolver.java
+++ b/src/main/java/org/warp/picalculator/math/MathSolver.java
@@ -19,9 +19,9 @@ public class MathSolver {
 	private int consecutiveNullSteps = 0;
 	private enum StepState {
 		_1_CALCULATION,
-		_2_REDUCTION,
+		_2_EXPANSION,
 		_3_CALCULATION,
-		_4_EXPANSION
+		_4_REDUCTION
 	}
 	private final StepState[] stepStates = StepState.values();
 	@SuppressWarnings("unchecked")
@@ -73,45 +73,33 @@ public class MathSolver {
 	}
 	
 	private ObjectArrayList<Function> solveStep(ObjectArrayList<Function> fncs) throws InterruptedException, Error {
+		ObjectArrayList<Function> processedFncs = applyRules(fncs, RuleType.EXISTENCE); // Apply existence rules before everything
+		if (processedFncs != null) {
+			fncs = processedFncs;
+		}
 		RuleType currentAcceptedRules;
 		switch(stepStates[stepState]) {
 			case _1_CALCULATION: {
 				currentAcceptedRules = RuleType.CALCULATION;
 				break;
 			}
-			case _2_REDUCTION: {
-				currentAcceptedRules = RuleType.REDUCTION;
+			case _2_EXPANSION: {
+				currentAcceptedRules = RuleType.EXPANSION;
 				break;
 			}
 			case _3_CALCULATION: {
 				currentAcceptedRules = RuleType.CALCULATION;
 				break;
 			}
-			case _4_EXPANSION: {
-				currentAcceptedRules = RuleType.EXPANSION;
+			case _4_REDUCTION: {
+				currentAcceptedRules = RuleType.REDUCTION;
 				break;
 			}
 			default:
 				System.err.println("Unknown Step State");
 				throw new NotImplementedException();
 		}
-		ObjectArrayList<Rule> rules = initialFunction.getMathContext().getAcceptableRules(currentAcceptedRules);
-		ObjectArrayList<Function> results = null;
-		Rule appliedRule = null;
-		for (Function fnc : fncs) {
-			for (Rule rule : rules) {
-				List<Function> ruleResults = fnc.simplify(rule);
-				if (ruleResults != null && !ruleResults.isEmpty()) {
-					if (results == null) results = new ObjectArrayList<Function>();
-					results.addAll(ruleResults);
-					appliedRule = rule;
-					break;
-				}
-			}
-		}
-		if (StaticVars.debugOn & results != null & appliedRule != null) {
-			Utils.out.println(Utils.OUTPUTLEVEL_NODEBUG, stepStates[stepState].toString().substring(3) + ": " + appliedRule.getRuleName());
-		}
+		ObjectArrayList<Function> results = applyRules(fncs, currentAcceptedRules);
 		switch(stepStates[stepState]) {
 			case _1_CALCULATION: {
 				if (results == null) {
@@ -125,7 +113,7 @@ public class MathSolver {
 				}
 				break;
 			}
-			case _2_REDUCTION: {
+			case _2_EXPANSION: {
 				if (results == null) {
 					if (currentStepStateN == 0) {
 						stepState += 2;
@@ -154,7 +142,7 @@ public class MathSolver {
 				}
 				break;
 			}
-			case _4_EXPANSION: {
+			case _4_REDUCTION: {
 				if (results == null) {
 					stepState = 1;
 					consecutiveNullSteps++;
@@ -173,4 +161,25 @@ public class MathSolver {
 		}
 		return null;
 	}
+	
+	private ObjectArrayList<Function> applyRules(ObjectArrayList<Function> fncs, RuleType currentAcceptedRules) throws InterruptedException, Error {
+		ObjectArrayList<Rule> rules = initialFunction.getMathContext().getAcceptableRules(currentAcceptedRules);
+		ObjectArrayList<Function> results = null;
+		Rule appliedRule = null;
+		for (Function fnc : fncs) {
+			for (Rule rule : rules) {
+				List<Function> ruleResults = fnc.simplify(rule);
+				if (ruleResults != null && !ruleResults.isEmpty()) {
+					if (results == null) results = new ObjectArrayList<Function>();
+					results.addAll(ruleResults);
+					appliedRule = rule;
+					break;
+				}
+			}
+		}
+		if (StaticVars.debugOn & results != null & appliedRule != null) {
+			Utils.out.println(Utils.OUTPUTLEVEL_NODEBUG, stepStates[stepState].toString().substring(3) + ": " + appliedRule.getRuleName());
+		}
+		return results;
+	}
 }
diff --git a/src/main/java/org/warp/picalculator/math/MathematicalSymbols.java b/src/main/java/org/warp/picalculator/math/MathematicalSymbols.java
index 96ed1150..fc2f4af2 100755
--- a/src/main/java/org/warp/picalculator/math/MathematicalSymbols.java
+++ b/src/main/java/org/warp/picalculator/math/MathematicalSymbols.java
@@ -25,6 +25,7 @@ public class MathematicalSymbols {
 	public static final char ARC_SINE = 'Ⓕ';
 	public static final char ARC_COSINE = 'Ⓖ';
 	public static final char ARC_TANGENT = 'Ⓗ';
+	public static final char UNDEFINED = '∅';
 	public static final char PI = 'π';
 
 	public static final char[] functionsNSN = new char[] { NTH_ROOT, POWER };
@@ -48,7 +49,7 @@ public class MathematicalSymbols {
 
 	public static final char[] parentheses = new char[] { PARENTHESIS_OPEN, PARENTHESIS_CLOSE };
 
-	public static final char[] variables = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'ⓧ', 'Ⓨ', 'Z', PI };
+	public static final char[] variables = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'ⓧ', 'Ⓨ', 'Z', PI, UNDEFINED };
 
 	public static final char[] genericSyntax = new char[] { SYSTEM, EQUATION };
 
diff --git a/src/main/java/org/warp/picalculator/math/functions/Undefined.java b/src/main/java/org/warp/picalculator/math/functions/Undefined.java
index 4f8153a3..b7849532 100755
--- a/src/main/java/org/warp/picalculator/math/functions/Undefined.java
+++ b/src/main/java/org/warp/picalculator/math/functions/Undefined.java
@@ -5,8 +5,11 @@ import java.util.List;
 import org.warp.picalculator.Error;
 import org.warp.picalculator.Errors;
 import org.warp.picalculator.gui.expression.blocks.Block;
+import org.warp.picalculator.gui.expression.blocks.BlockChar;
+import org.warp.picalculator.gui.expression.blocks.BlockUndefined;
 import org.warp.picalculator.math.Function;
 import org.warp.picalculator.math.MathContext;
+import org.warp.picalculator.math.MathematicalSymbols;
 import org.warp.picalculator.math.rules.Rule;
 
 import it.unimi.dsi.fastutil.objects.ObjectArrayList;
@@ -53,9 +56,15 @@ public class Undefined implements Function {
 	}
 
 	@Override
-	public ObjectArrayList<Block> toBlock(MathContext context) throws Error {
-		// TODO Auto-generated method stub
-		throw new Error(Errors.NOT_IMPLEMENTED, "Unknown function " + getClass().getSimpleName());
+	public ObjectArrayList<Block> toBlock(MathContext context) {
+		ObjectArrayList<Block> result = new ObjectArrayList<>();
+		result.add(new BlockUndefined());
+		return result;
+	}
+	
+	@Override
+	public String toString() {
+		return "UNDEFINED";
 	}
 
 }
diff --git a/src/main/java/org/warp/picalculator/math/rules/FractionsRule12.java b/src/main/java/org/warp/picalculator/math/rules/FractionsRule12.java
deleted file mode 100755
index f6a623e5..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/FractionsRule12.java
+++ /dev/null
@@ -1,49 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.functions.Division;
-import org.warp.picalculator.math.functions.Expression;
-import org.warp.picalculator.math.functions.Multiplication;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Fractions rule<br>
- * <b>(b / c) / a = b / (a * c)</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class FractionsRule12 {
-
-	public static boolean compare(Function f) throws InterruptedException {
-		final Division fnc = (Division) f;
-		Function a;
-		Function c;
-		if (fnc.getParameter1() instanceof Division) {
-			final Division div2 = (Division) fnc.getParameter1();
-			a = fnc.getParameter1();
-			c = div2.getParameter2();
-			return new Multiplication(fnc.getMathContext(), a, c).simplify(this) != null;
-		}
-		return false;
-	}
-
-	public static ObjectArrayList<Function> execute(Function f) throws Error {
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		final Division fnc = (Division) f;
-		Function a;
-		Function b;
-		Function c;
-
-		final Division div2 = (Division) fnc.getParameter1();
-		a = fnc.getParameter2();
-		b = div2.getParameter1();
-		c = div2.getParameter2();
-		result.add(new Division(fnc.getMathContext(), new Multiplication(fnc.getMathContext(), new Expression(fnc.getMathContext(), a), new Expression(fnc.getMathContext(), c)), b));
-
-		return result;
-	}
-
-}
diff --git a/src/main/java/org/warp/picalculator/math/rules/FractionsRule14.java b/src/main/java/org/warp/picalculator/math/rules/FractionsRule14.java
deleted file mode 100755
index 42d15aaf..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/FractionsRule14.java
+++ /dev/null
@@ -1,84 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.functions.Division;
-import org.warp.picalculator.math.functions.Multiplication;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Fractions rule<br>
- * <b>(a / b) * (c / d) = (a * c) / (b * d)</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class FractionsRule14 {
-
-	public static boolean compare(Function f) throws InterruptedException {
-		final Multiplication fnc = (Multiplication) f;
-		Function a;
-		Function b;
-		Function c;
-		Function d;
-		if (fnc.getParameter1() instanceof Division && fnc.getParameter2() instanceof Division) {
-			final Division div1 = (Division) fnc.getParameter1();
-			final Division div2 = (Division) fnc.getParameter2();
-			a = div1.getParameter1();
-			b = div1.getParameter2();
-			c = div2.getParameter1();
-			d = div2.getParameter2();
-			return new Multiplication(f.getMathContext(), a, c).simplify(this) != null || new Multiplication(f.getMathContext(), b, d).isSimplified() == false;
-		} else if (fnc.getParameter1() instanceof Division) {
-			final Division div1 = (Division) fnc.getParameter1();
-			a = div1.getParameter1();
-			b = div1.getParameter2();
-			c = fnc.getParameter2();
-			return new Multiplication(f.getMathContext(), a, c).simplify(this) != null;
-		} else if (fnc.getParameter2() instanceof Division) {
-			final Division div2 = (Division) fnc.getParameter2();
-			a = fnc.getParameter1();
-			c = div2.getParameter1();
-			d = div2.getParameter2();
-			return new Multiplication(f.getMathContext(), a, c).simplify(this) != null;
-		}
-		return false;
-	}
-
-	public static ObjectArrayList<Function> execute(Function f) throws Error {
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		final Multiplication fnc = (Multiplication) f;
-		Function a;
-		Function b;
-		Function c;
-		Function d;
-
-		if (fnc.getParameter1() instanceof Division && fnc.getParameter2() instanceof Division) {
-			final Division div1 = (Division) fnc.getParameter1();
-			final Division div2 = (Division) fnc.getParameter2();
-			a = div1.getParameter1();
-			b = div1.getParameter2();
-			c = div2.getParameter1();
-			d = div2.getParameter2();
-			final Division div = new Division(fnc.getMathContext(), new Multiplication(fnc.getMathContext(), a, c), new Multiplication(fnc.getMathContext(), b, d));
-			result.add(div);
-		} else if (fnc.getParameter1() instanceof Division) {
-			final Division div1 = (Division) fnc.getParameter1();
-			a = div1.getParameter1();
-			b = div1.getParameter2();
-			c = fnc.getParameter2();
-			final Division div = new Division(fnc.getMathContext(), new Multiplication(fnc.getMathContext(), a, c), b);
-			result.add(div);
-		} else if (fnc.getParameter2() instanceof Division) {
-			final Division div2 = (Division) fnc.getParameter2();
-			a = fnc.getParameter1();
-			c = div2.getParameter1();
-			d = div2.getParameter2();
-			final Division div = new Division(fnc.getMathContext(), new Multiplication(fnc.getMathContext(), a, c), d);
-			result.add(div);
-		}
-		return result;
-	}
-
-}
diff --git a/src/main/java/org/warp/picalculator/math/rules/NumberRule1.java b/src/main/java/org/warp/picalculator/math/rules/NumberRule1.java
deleted file mode 100755
index 29cf7029..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/NumberRule1.java
+++ /dev/null
@@ -1,44 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.MathContext;
-import org.warp.picalculator.math.functions.Multiplication;
-import org.warp.picalculator.math.functions.Number;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Number rule<br>
- * <b>a * 0 = 0</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class NumberRule1 {
-
-	public static boolean compare(Function f) {
-		final MathContext root = f.getMathContext();
-		final Multiplication mult = (Multiplication) f;
-		if (mult.getParameter1() instanceof Number) {
-			final Number numb = (Number) mult.getParameter1();
-			if (numb.equals(new Number(root, 0))) {
-				return true;
-			}
-		}
-		if (mult.getParameter2() instanceof Number) {
-			final Number numb = (Number) mult.getParameter2();
-			if (numb.equals(new Number(root, 0))) {
-				return true;
-			}
-		}
-		return false;
-	}
-
-	public static ObjectArrayList<Function> execute(Function f) throws Error {
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		result.add(new Number(f.getMathContext(), "0"));
-		return result;
-	}
-
-}
diff --git a/src/main/java/org/warp/picalculator/math/rules/NumberRule2.java b/src/main/java/org/warp/picalculator/math/rules/NumberRule2.java
deleted file mode 100755
index 817fadb0..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/NumberRule2.java
+++ /dev/null
@@ -1,63 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.MathContext;
-import org.warp.picalculator.math.functions.Multiplication;
-import org.warp.picalculator.math.functions.Number;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Number rule<br>
- * <b>a * 1 = a</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class NumberRule2 {
-
-	public static boolean compare(Function f) {
-		final MathContext root = f.getMathContext();
-		final Multiplication mult = (Multiplication) f;
-		if (mult.getParameter1() instanceof Number) {
-			final Number numb = (Number) mult.getParameter1();
-			if (numb.equals(new Number(root, 1))) {
-				return true;
-			}
-		}
-		if (mult.getParameter2() instanceof Number) {
-			final Number numb = (Number) mult.getParameter2();
-			if (numb.equals(new Number(root, 1))) {
-				return true;
-			}
-		}
-		return false;
-	}
-
-	public static ObjectArrayList<Function> execute(Function f) throws Error {
-		final MathContext root = f.getMathContext();
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		Function a = null;
-		boolean aFound = false;
-		final Multiplication mult = (Multiplication) f;
-		if (aFound == false & mult.getParameter1() instanceof Number) {
-			final Number numb = (Number) mult.getParameter1();
-			if (numb.equals(new Number(root, 1))) {
-				a = mult.getParameter2();
-				aFound = true;
-			}
-		}
-		if (aFound == false && mult.getParameter2() instanceof Number) {
-			final Number numb = (Number) mult.getParameter2();
-			if (numb.equals(new Number(root, 1))) {
-				a = mult.getParameter1();
-				aFound = true;
-			}
-		}
-
-		result.add(a);
-		return result;
-	}
-
-}
diff --git a/src/main/java/org/warp/picalculator/math/rules/NumberRule3.java b/src/main/java/org/warp/picalculator/math/rules/NumberRule3.java
deleted file mode 100755
index edc8a816..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/NumberRule3.java
+++ /dev/null
@@ -1,60 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.MathContext;
-import org.warp.picalculator.math.functions.Multiplication;
-import org.warp.picalculator.math.functions.Negative;
-import org.warp.picalculator.math.functions.Number;
-import org.warp.picalculator.math.functions.Subtraction;
-import org.warp.picalculator.math.functions.Sum;
-import org.warp.picalculator.math.functions.SumSubtraction;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Number rule<br>
- * <b>a - a = 0</b><br>
- * <b>-a + a = 0</b><br>
- * <b>a ± a = {0, 2a}</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class NumberRule3 {
-
-	public static boolean compare(Function f) {
-		if (f instanceof Subtraction) {
-			final Subtraction sub = (Subtraction) f;
-			if (sub.getParameter1().equals(sub.getParameter2())) {
-				return true;
-			}
-		} else if (f instanceof Sum) {
-			final Sum sub = (Sum) f;
-			if (sub.getParameter1() instanceof Negative) {
-				final Negative neg = (Negative) sub.getParameter1();
-				if (neg.getParameter().equals(sub.getParameter2())) {
-					return true;
-				}
-			}
-		} else if (f instanceof SumSubtraction) {
-			final SumSubtraction sub = (SumSubtraction) f;
-			if (sub.getParameter1().equals(sub.getParameter2())) {
-				return true;
-			}
-		}
-		return false;
-	}
-
-	public static ObjectArrayList<Function> execute(Function f) throws Error {
-		final MathContext root = f.getMathContext();
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		if (f instanceof SumSubtraction) {
-			final Multiplication mul = new Multiplication(root, new Number(root, 2), ((SumSubtraction) f).getParameter1());
-			result.add(mul);
-		}
-		result.add(new Number(root, 0));
-		return result;
-	}
-
-}
diff --git a/src/main/java/org/warp/picalculator/math/rules/NumberRule4.java b/src/main/java/org/warp/picalculator/math/rules/NumberRule4.java
deleted file mode 100755
index c90ffbb9..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/NumberRule4.java
+++ /dev/null
@@ -1,37 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.MathContext;
-import org.warp.picalculator.math.functions.Subtraction;
-import org.warp.picalculator.math.functions.Sum;
-import org.warp.picalculator.math.functions.SumSubtraction;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Number rule<br>
- * <b>a ± b = {a+b, a-b}</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class NumberRule4 {
-
-	public static boolean compare(Function f) {
-		if (f instanceof SumSubtraction) {
-			return true;
-		}
-		return false;
-	}
-
-	public static ObjectArrayList<Function> execute(Function f) throws Error {
-		final MathContext root = f.getMathContext();
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		final SumSubtraction ss = (SumSubtraction) f;
-		result.add(new Sum(root, ss.getParameter1(), ss.getParameter2()));
-		result.add(new Subtraction(root, ss.getParameter1(), ss.getParameter2()));
-		return result;
-	}
-
-}
diff --git a/src/main/java/org/warp/picalculator/math/rules/NumberRule5.java b/src/main/java/org/warp/picalculator/math/rules/NumberRule5.java
deleted file mode 100755
index 5874f46e..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/NumberRule5.java
+++ /dev/null
@@ -1,46 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.FunctionOperator;
-import org.warp.picalculator.math.MathContext;
-import org.warp.picalculator.math.functions.Number;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Number rule<br>
- * <b>a + 0 = a</b><br>
- * <b>0 + a = a</b><br>
- * <b>a - 0 = a</b><br>
- * <b>0 - a = a</b><br>
- * <b>a ± 0 = a</b><br>
- * <b>0 ± a = a</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class NumberRule5 {
-
-	public static boolean compare(Function f) {
-		final MathContext root = f.getMathContext();
-		final FunctionOperator fnc = (FunctionOperator) f;
-		if (fnc.getParameter1().equals(new Number(root, 0)) || fnc.getParameter2().equals(new Number(root, 0))) {
-			return true;
-		}
-		return false;
-	}
-
-	public static ObjectArrayList<Function> execute(Function f) throws Error {
-		final MathContext root = f.getMathContext();
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		final FunctionOperator fnc = (FunctionOperator) f;
-		Function a = fnc.getParameter1();
-		if (a.equals(new Number(root, 0))) {
-			a = fnc.getParameter2();
-		}
-		result.add(a);
-		return result;
-	}
-
-}
diff --git a/src/main/java/org/warp/picalculator/math/rules/NumberRule7.java b/src/main/java/org/warp/picalculator/math/rules/NumberRule7.java
deleted file mode 100755
index 3fc042a5..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/NumberRule7.java
+++ /dev/null
@@ -1,33 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.MathContext;
-import org.warp.picalculator.math.functions.Multiplication;
-import org.warp.picalculator.math.functions.Number;
-import org.warp.picalculator.math.functions.Sum;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Number rule<br>
- * <b>a + a = 2a</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class NumberRule7 {
-
-	public static boolean compare(Sum f) {
-		return f.getParameter1().equals(f.getParameter2());
-	}
-
-	public static ObjectArrayList<Function> execute(Sum f) throws Error {
-		final MathContext root = f.getMathContext();
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		final Multiplication mult = new Multiplication(root, new Number(root, 2), f.getParameter1());
-		result.add(mult);
-		return result;
-	}
-
-}
diff --git a/src/main/java/org/warp/picalculator/math/rules/RuleType.java b/src/main/java/org/warp/picalculator/math/rules/RuleType.java
index a3130b27..3a8db9a9 100644
--- a/src/main/java/org/warp/picalculator/math/rules/RuleType.java
+++ b/src/main/java/org/warp/picalculator/math/rules/RuleType.java
@@ -1,7 +1,20 @@
 package org.warp.picalculator.math.rules;
 
 public enum RuleType {
-	EXPANSION,
+	/**
+	 * A rule that tries to factorize and group a polynomial expression into a shorter expression
+	 */
 	REDUCTION,
-	CALCULATION
+	/**
+	 * A rule that tries to transform an expression to a simple polynomial expression
+	 */
+	EXPANSION,
+	/**
+	 * Calculation
+	 */
+	CALCULATION,
+	/**
+	 * Existence
+	 */
+	EXISTENCE
 }
diff --git a/src/main/java/org/warp/picalculator/math/rules/RulesManager.java b/src/main/java/org/warp/picalculator/math/rules/RulesManager.java
index 418a01e4..377f60e7 100644
--- a/src/main/java/org/warp/picalculator/math/rules/RulesManager.java
+++ b/src/main/java/org/warp/picalculator/math/rules/RulesManager.java
@@ -117,6 +117,6 @@ public class RulesManager {
 	
 	public static void addRule(Rule rule) {
 		rules[rule.getRuleType().ordinal()].add(rule);
-		Utils.out.println(Utils.OUTPUTLEVEL_NODEBUG, "Loaded rule " + rule.getRuleName());
+		Utils.out.println(Utils.OUTPUTLEVEL_NODEBUG, "Loaded rule " + rule.getRuleName() + " as " + rule.getRuleType() + " rule.");
 	}
 }
diff --git a/src/main/java/org/warp/picalculator/math/rules/UndefinedRule1.java b/src/main/java/org/warp/picalculator/math/rules/UndefinedRule1.java
deleted file mode 100755
index 4444e571..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/UndefinedRule1.java
+++ /dev/null
@@ -1,37 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.MathContext;
-import org.warp.picalculator.math.functions.Number;
-import org.warp.picalculator.math.functions.Power;
-import org.warp.picalculator.math.functions.Undefined;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Undefined rule<br>
- * <b>0^0=undefined</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class UndefinedRule1 {
-
-	public static boolean compare(Function f) {
-		final MathContext root = f.getMathContext();
-		final Power fnc = (Power) f;
-		if (fnc.getParameter1().equals(new Number(root, 0)) && fnc.getParameter2().equals(new Number(root, 0))) {
-			return true;
-		}
-		return false;
-	}
-
-	public static ObjectArrayList<Function> execute(Function f) throws Error {
-		final MathContext root = f.getMathContext();
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		result.add(new Undefined(root));
-		return result;
-	}
-
-}
diff --git a/src/main/java/org/warp/picalculator/math/rules/UndefinedRule2.java b/src/main/java/org/warp/picalculator/math/rules/UndefinedRule2.java
deleted file mode 100755
index 4222e728..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/UndefinedRule2.java
+++ /dev/null
@@ -1,40 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.MathContext;
-import org.warp.picalculator.math.functions.Division;
-import org.warp.picalculator.math.functions.Number;
-import org.warp.picalculator.math.functions.Undefined;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Undefined rule<br>
- * <b>a / 0 = undefined</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class UndefinedRule2 {
-
-	public static boolean compare(Function f) {
-		final MathContext root = f.getMathContext();
-		final Division fnc = (Division) f;
-		if (fnc.getParameter2() instanceof Number) {
-			final Number numb = (Number) fnc.getParameter2();
-			if (numb.equals(new Number(root, 0))) {
-				return true;
-			}
-		}
-		return false;
-	}
-
-	public static ObjectArrayList<Function> execute(Function f) throws Error {
-		final MathContext root = f.getMathContext();
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		result.add(new Undefined(root));
-		return result;
-	}
-
-}
diff --git a/src/main/java/org/warp/picalculator/math/rules/VariableRule1.java b/src/main/java/org/warp/picalculator/math/rules/VariableRule1.java
deleted file mode 100755
index 97e13fdf..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/VariableRule1.java
+++ /dev/null
@@ -1,63 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.FunctionOperator;
-import org.warp.picalculator.math.MathContext;
-import org.warp.picalculator.math.functions.Expression;
-import org.warp.picalculator.math.functions.Multiplication;
-import org.warp.picalculator.math.functions.Subtraction;
-import org.warp.picalculator.math.functions.Sum;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Variable rule<br>
- * <b>ax+bx=(a+b)*x (a,b NUMBER; x VARIABLE|MULTIPLICATION)</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class VariableRule1 {
-
-	public static boolean compare(FunctionOperator fnc) {
-		if (fnc.getParameter1() instanceof Multiplication & fnc.getParameter2() instanceof Multiplication) {
-			final Multiplication m1 = (Multiplication) fnc.getParameter1();
-			final Multiplication m2 = (Multiplication) fnc.getParameter2();
-			if (m1.getParameter1().equals(m2.getParameter1()) || m1.getParameter2().equals(m2.getParameter2())) {
-				return true;
-			}
-		}
-		return false;
-	}
-
-	public static ObjectArrayList<Function> execute(FunctionOperator fnc) throws Error {
-		final MathContext root = fnc.getMathContext();
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		final Multiplication m1 = (Multiplication) fnc.getParameter1();
-		final Multiplication m2 = (Multiplication) fnc.getParameter2();
-		final Function a;
-		final Function b;
-		final Function x;
-		if (m1.getParameter2().equals(m2.getParameter2())) {
-			x = m1.getParameter2();
-			a = m1.getParameter1();
-			b = m2.getParameter1();
-		} else {
-			x = m1.getParameter1();
-			a = m1.getParameter2();
-			b = m2.getParameter2();
-		}
-
-		FunctionOperator rets;
-		if (fnc instanceof Sum) {
-			rets = new Sum(root, a, b);
-		} else {
-			rets = new Subtraction(root, a, b);
-		}
-		final Multiplication retm = new Multiplication(root, rets, x);
-		result.add(retm);
-		return result;
-	}
-
-}
diff --git a/src/main/java/org/warp/picalculator/math/rules/VariableRule2.java b/src/main/java/org/warp/picalculator/math/rules/VariableRule2.java
deleted file mode 100755
index 5409dbb6..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/VariableRule2.java
+++ /dev/null
@@ -1,52 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.FunctionOperator;
-import org.warp.picalculator.math.MathContext;
-import org.warp.picalculator.math.functions.Expression;
-import org.warp.picalculator.math.functions.Multiplication;
-import org.warp.picalculator.math.functions.Number;
-import org.warp.picalculator.math.functions.Subtraction;
-import org.warp.picalculator.math.functions.Sum;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Variable rule<br>
- * <b>ax+x=(a+1)*x (a,b NUMBER; x VARIABLES)</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class VariableRule2 {
-
-	public static boolean compare(FunctionOperator fnc) {
-		if (fnc.getParameter1() instanceof Multiplication) {
-			final Multiplication m1 = (Multiplication) fnc.getParameter1();
-			if (m1.getParameter2().equals(fnc.getParameter2())) {
-				return true;
-			}
-		}
-		return false;
-	}
-
-	public static ObjectArrayList<Function> execute(FunctionOperator fnc) throws Error {
-		final MathContext root = fnc.getMathContext();
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		final Multiplication m1 = (Multiplication) fnc.getParameter1();
-		final Function a = m1.getParameter1();
-		final Function x = fnc.getParameter2();
-
-		FunctionOperator rets;
-		if (fnc instanceof Sum) {
-			rets = new Sum(root, a, new Number(root, 1));
-		} else {
-			rets = new Subtraction(root, a, new Number(root, 1));
-		}
-		final Multiplication retm = new Multiplication(root, rets, x);
-		result.add(retm);
-		return result;
-	}
-
-}
diff --git a/src/main/java/org/warp/picalculator/math/rules/VariableRule3.java b/src/main/java/org/warp/picalculator/math/rules/VariableRule3.java
deleted file mode 100755
index 6d378c3c..00000000
--- a/src/main/java/org/warp/picalculator/math/rules/VariableRule3.java
+++ /dev/null
@@ -1,53 +0,0 @@
-package org.warp.picalculator.math.rules;
-
-import org.warp.picalculator.Error;
-import org.warp.picalculator.math.Function;
-import org.warp.picalculator.math.FunctionOperator;
-import org.warp.picalculator.math.MathContext;
-import org.warp.picalculator.math.functions.Expression;
-import org.warp.picalculator.math.functions.Multiplication;
-import org.warp.picalculator.math.functions.Number;
-import org.warp.picalculator.math.functions.Subtraction;
-import org.warp.picalculator.math.functions.Sum;
-
-import it.unimi.dsi.fastutil.objects.ObjectArrayList;
-
-/**
- * Variable rule<br>
- * <b>x+ax=(a+1)*x (a,b NUMBER; x VARIABLES)</b>
- * 
- * @author Andrea Cavalli
- *
- */
-public class VariableRule3 {
-
-	public static boolean compare(FunctionOperator fnc) {
-		if (fnc.getParameter2() instanceof Multiplication) {
-			final Multiplication m2 = (Multiplication) fnc.getParameter2();
-			if (m2.getParameter2().equals(fnc.getParameter1())) {
-				return true;
-			}
-		}
-		return false;
-	}
-
-	public static ObjectArrayList<Function> execute(FunctionOperator fnc) throws Error {
-		final MathContext root = fnc.getMathContext();
-		final ObjectArrayList<Function> result = new ObjectArrayList<>();
-		final Multiplication m2 = (Multiplication) fnc.getParameter2();
-		final Function a = m2.getParameter1();
-		final Function x = fnc.getParameter1();
-
-		FunctionOperator rets;
-		if (fnc instanceof Sum) {
-			rets = new Sum(root, new Number(root, 1), a);
-		} else {
-			rets = new Subtraction(root, new Number(root, 1), a);
-		}
-
-		final Multiplication retm = new Multiplication(root, rets, x);
-		result.add(retm);
-		return result;
-	}
-
-}
diff --git a/src/main/resources/rules.csv b/src/main/resources/rules.csv
index ae79e057..9dd05b34 100644
--- a/src/main/resources/rules.csv
+++ b/src/main/resources/rules.csv
@@ -29,3 +29,16 @@ FractionsRule3
 FractionsRule4
 FractionsRule5
 FractionsRule11
+FractionsRule12
+FractionsRule14
+NumberRule1
+NumberRule2
+NumberRule3
+NumberRule4
+NumberRule5
+NumberRule7
+UndefinedRule1
+UndefinedRule2
+VariableRule1
+VariableRule2
+VariableRule3
diff --git a/src/main/resources/rules/FractionsRule12.js b/src/main/resources/rules/FractionsRule12.js
new file mode 100644
index 00000000..a8261e9f
--- /dev/null
+++ b/src/main/resources/rules/FractionsRule12.js
@@ -0,0 +1,68 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var Division = org.warp.picalculator.math.functions.Division;
+var Multiplication = org.warp.picalculator.math.functions.Multiplication;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Fractions rule
+ * (b / c) / a = b / (a * c)
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "FractionsRule12";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.EXPANSION;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		if (ScriptUtils.instanceOf(f, Division.class)) {
+			var fnc = f;
+			var a;
+			var c;
+			if (ScriptUtils.instanceOf(fnc.getParameter1(), Division.class)) {
+				var div2 = fnc.getParameter1();
+				a = fnc.getParameter1();
+				c = div2.getParameter2();
+				isExecutable = true;
+			}
+		}
+	
+		if (isExecutable) {
+			var result = new ObjectArrayList();
+			var fnc = f;
+			var a;
+			var b;
+			var c;
+	
+			var div2 = fnc.getParameter1();
+			a = fnc.getParameter2();
+			b = div2.getParameter1();
+			c = div2.getParameter2();
+			result.add(new Division(fnc.getMathContext(), new Multiplication(fnc.getMathContext(), a, c), b));
+	
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file
diff --git a/src/main/resources/rules/FractionsRule14.js b/src/main/resources/rules/FractionsRule14.js
new file mode 100644
index 00000000..e9cb0e42
--- /dev/null
+++ b/src/main/resources/rules/FractionsRule14.js
@@ -0,0 +1,104 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var Division = org.warp.picalculator.math.functions.Division;
+var Multiplication = org.warp.picalculator.math.functions.Multiplication;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Fractions rule
+ * (a / b) * (c / d) = (a * c) / (b * d)
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "FractionsRule14";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.EXPANSION;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		if (ScriptUtils.instanceOf(f, Multiplication.class)) {
+			var fnc = f;
+			var a;
+			var b;
+			var c;
+			var d;
+			if (ScriptUtils.instanceOf(fnc.getParameter1(), Division.class) && ScriptUtils.instanceOf(fnc.getParameter2(), Division.class)) {
+				var div1 = fnc.getParameter1();
+				var div2 = fnc.getParameter2();
+				a = div1.getParameter1();
+				b = div1.getParameter2();
+				c = div2.getParameter1();
+				d = div2.getParameter2();
+				isExecutable = true;
+			} else if (ScriptUtils.instanceOf(fnc.getParameter1(), Division.class)) {
+				var div1 = fnc.getParameter1();
+				a = div1.getParameter1();
+				b = div1.getParameter2();
+				c = fnc.getParameter2();
+				isExecutable = true;
+			} else if (ScriptUtils.instanceOf(fnc.getParameter2(), Division.class)) {
+				var div2 = fnc.getParameter2();
+				a = fnc.getParameter1();
+				c = div2.getParameter1();
+				d = div2.getParameter2();
+				isExecutable = true;
+			}
+		}
+	
+		if (isExecutable) {
+			var result = new ObjectArrayList();
+			var fnc = f;
+			var a;
+			var b;
+			var c;
+			var d;
+	
+			if (ScriptUtils.instanceOf(fnc.getParameter1(), Division.class) && ScriptUtils.instanceOf(fnc.getParameter2(), Division.class)) {
+				var div1 = fnc.getParameter1();
+				var div2 = fnc.getParameter2();
+				a = div1.getParameter1();
+				b = div1.getParameter2();
+				c = div2.getParameter1();
+				d = div2.getParameter2();
+				var div = new Division(fnc.getMathContext(), new Multiplication(fnc.getMathContext(), a, c), new Multiplication(fnc.getMathContext(), b, d));
+				result.add(div);
+			} else if (ScriptUtils.instanceOf(fnc.getParameter1(), Division.class)) {
+				var div1 = fnc.getParameter1();
+				a = div1.getParameter1();
+				b = div1.getParameter2();
+				c = fnc.getParameter2();
+				var div = new Division(fnc.getMathContext(), new Multiplication(fnc.getMathContext(), a, c), b);
+				result.add(div);
+			} else if (ScriptUtils.instanceOf(fnc.getParameter2(), Division.class)) {
+				var div2 = fnc.getParameter2();
+				a = fnc.getParameter1();
+				c = div2.getParameter1();
+				d = div2.getParameter2();
+				var div = new Division(fnc.getMathContext(), new Multiplication(fnc.getMathContext(), a, c), d);
+				result.add(div);
+			}
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file
diff --git a/src/main/resources/rules/NumberRule1.js b/src/main/resources/rules/NumberRule1.js
new file mode 100644
index 00000000..f15979bf
--- /dev/null
+++ b/src/main/resources/rules/NumberRule1.js
@@ -0,0 +1,64 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var MathContext = org.warp.picalculator.math.MathContext;
+var Multiplication = org.warp.picalculator.math.functions.Multiplication;
+var Number = org.warp.picalculator.math.functions.Number;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Number rule
+ * a * 0 = 0
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "NumberRule1";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.CALCULATION;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		if (ScriptUtils.instanceOf(f, Multiplication.class)) {
+			var root = f.getMathContext();
+			var mult = f;
+			if (ScriptUtils.instanceOf(mult.getParameter1(), Number.class)) {
+				var numb = mult.getParameter1();
+				if (numb.equals(new Number(root, 0))) {
+					isExecutable = true;
+				}
+			}
+			if (ScriptUtils.instanceOf(mult.getParameter2(), Number.class)) {
+				var numb = mult.getParameter2();
+				if (numb.equals(new Number(root, 0))) {
+					isExecutable = true;
+				}
+			}
+		}
+	
+		if (isExecutable) {
+			var result = new ObjectArrayList();
+			result.add(new Number(f.getMathContext(), "0"));
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file
diff --git a/src/main/resources/rules/NumberRule2.js b/src/main/resources/rules/NumberRule2.js
new file mode 100644
index 00000000..28500067
--- /dev/null
+++ b/src/main/resources/rules/NumberRule2.js
@@ -0,0 +1,83 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var MathContext = org.warp.picalculator.math.MathContext;
+var Multiplication = org.warp.picalculator.math.functions.Multiplication;
+var Number = org.warp.picalculator.math.functions.Number;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Number rule
+ * a * 1 = a
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "NumberRule2";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.CALCULATION;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		if (ScriptUtils.instanceOf(f, Multiplication.class)) {
+			var root = f.getMathContext();
+			var mult = f;
+			if (ScriptUtils.instanceOf(mult.getParameter1(), Number.class)) {
+				var numb = mult.getParameter1();
+				if (numb.equals(new Number(root, 1))) {
+					isExecutable = true;
+				}
+			}
+			if (ScriptUtils.instanceOf(mult.getParameter2(), Number.class)) {
+				var numb = mult.getParameter2();
+				if (numb.equals(new Number(root, 1))) {
+					isExecutable = true;
+				}
+			}
+		}
+	
+		if (isExecutable) {
+			var root = f.getMathContext();
+			var result = new ObjectArrayList();
+			var a = null;
+			var aFound = false;
+			var mult = f;
+			if (aFound == false & ScriptUtils.instanceOf(mult.getParameter1(), Number.class)) {
+				var numb = mult.getParameter1();
+				if (numb.equals(new Number(root, 1))) {
+					a = mult.getParameter2();
+					aFound = true;
+				}
+			}
+			if (aFound == false && ScriptUtils.instanceOf(mult.getParameter2(), Number.class)) {
+				var numb = mult.getParameter2();
+				if (numb.equals(new Number(root, 1))) {
+					a = mult.getParameter1();
+					aFound = true;
+				}
+			}
+	
+			result.add(a);
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file
diff --git a/src/main/resources/rules/NumberRule3.js b/src/main/resources/rules/NumberRule3.js
new file mode 100644
index 00000000..93acfaff
--- /dev/null
+++ b/src/main/resources/rules/NumberRule3.js
@@ -0,0 +1,80 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var MathContext = org.warp.picalculator.math.MathContext;
+var Multiplication = org.warp.picalculator.math.functions.Multiplication;
+var Negative = org.warp.picalculator.math.functions.Negative;
+var Number = org.warp.picalculator.math.functions.Number;
+var Subtraction = org.warp.picalculator.math.functions.Subtraction;
+var Sum = org.warp.picalculator.math.functions.Sum;
+var SumSubtraction = org.warp.picalculator.math.functions.SumSubtraction;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Number rule
+ * a - a = 0
+ * -a + a = 0
+ * a ± a = {0, 2a}
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "NumberRule3";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.CALCULATION;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		if (ScriptUtils.instanceOf(f, Subtraction.class)) {
+			var sub = f;
+			if (sub.getParameter1().equals(sub.getParameter2())) {
+				isExecutable = true;
+			}
+		} else if (ScriptUtils.instanceOf(f, Sum.class)) {
+			var sub = f;
+			if (ScriptUtils.instanceOf(sub.getParameter1(), Multiplication.class)) {
+				if (ScriptUtils.instanceOf(sub.getParameter1().getParameter1(), Number.class) && sub.getParameter1().getParameter1().equals(new Number(f.getMathContext(), -1))) {
+					var neg = sub.getParameter1().getParameter2();
+					if (neg.equals(sub.getParameter2())) {
+						isExecutable = true;
+					}
+				}
+			}
+		} else if (ScriptUtils.instanceOf(f, SumSubtraction.class)) {
+			var sub = f;
+			if (sub.getParameter1().equals(sub.getParameter2())) {
+				isExecutable = true;
+			}
+		}
+	
+		if (isExecutable) {
+			var root = f.getMathContext();
+			var result = new ObjectArrayList();
+			if (ScriptUtils.instanceOf(f, SumSubtraction.class)) {
+				var mul = new Multiplication(root, new Number(root, 2), f.getParameter1());
+				result.add(mul);
+			}
+			result.add(new Number(root, 0));
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file
diff --git a/src/main/resources/rules/NumberRule4.js b/src/main/resources/rules/NumberRule4.js
new file mode 100644
index 00000000..6db37fe8
--- /dev/null
+++ b/src/main/resources/rules/NumberRule4.js
@@ -0,0 +1,55 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var MathContext = org.warp.picalculator.math.MathContext;
+var Subtraction = org.warp.picalculator.math.functions.Subtraction;
+var Sum = org.warp.picalculator.math.functions.Sum;
+var SumSubtraction = org.warp.picalculator.math.functions.SumSubtraction;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Number rule
+ * a ± b = {a+b, a-b}
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "NumberRule4";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.EXPANSION;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		if (ScriptUtils.instanceOf(f, SumSubtraction.class)) {
+			isExecutable = true;
+		}
+	
+		if (isExecutable) {
+			var root = f.getMathContext();
+			var result = new ObjectArrayList();
+			var ss = f;
+			result.add(new Sum(root, ss.getParameter1(), ss.getParameter2()));
+			result.add(new Subtraction(root, ss.getParameter1(), ss.getParameter2()));
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file
diff --git a/src/main/resources/rules/NumberRule5.js b/src/main/resources/rules/NumberRule5.js
new file mode 100644
index 00000000..2e3d25aa
--- /dev/null
+++ b/src/main/resources/rules/NumberRule5.js
@@ -0,0 +1,71 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var FunctionOperator = org.warp.picalculator.math.FunctionOperator;
+var MathContext = org.warp.picalculator.math.MathContext;
+var Number = org.warp.picalculator.math.functions.Number;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Number rule
+ * a + 0 = a
+ * 0 + a = a
+ * a - 0 = a
+ * 0 - a = -a
+ * a ± 0 = a
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "NumberRule5";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.CALCULATION;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		if (ScriptUtils.instanceOf(f, Sum.class) || ScriptUtils.instanceOf(f, Subtraction.class) || ScriptUtils.instanceOf(f, SumSubtraction.class)) {
+			var root = f.getMathContext();
+			var fnc = f;
+			if (fnc.getParameter1().equals(new Number(root, 0)) || fnc.getParameter2().equals(new Number(root, 0))) {
+				if (!(fnc.getParameter1().equals(new Number(root, 0)) && ScriptUtils.instanceOf(f, SumSubtraction.class))) {
+					isExecutable = true;
+				}
+			}
+		}
+	
+		if (isExecutable) {
+			var root = f.getMathContext();
+			var result = new ObjectArrayList();
+			var fnc = f;
+			var a = fnc.getParameter1();
+			if (a.equals(new Number(root, 0))) {
+				if (ScriptUtils.instanceOf(f, Subtraction.class)) {
+					a = new Multiplication(root, new Number(root, -1), fnc.getParameter2());
+				} else {
+					a = fnc.getParameter2();
+				}
+			}
+			result.add(a);
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file
diff --git a/src/main/resources/rules/NumberRule7.js b/src/main/resources/rules/NumberRule7.js
new file mode 100644
index 00000000..2d431d69
--- /dev/null
+++ b/src/main/resources/rules/NumberRule7.js
@@ -0,0 +1,54 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var MathContext = org.warp.picalculator.math.MathContext;
+var Multiplication = org.warp.picalculator.math.functions.Multiplication;
+var Number = org.warp.picalculator.math.functions.Number;
+var Sum = org.warp.picalculator.math.functions.Sum;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Number rule
+ * a + a = 2a
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "NumberRule7";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.EXPANSION;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		if (ScriptUtils.instanceOf(f, Sum.class)) {
+			isExecutable = f.getParameter1().equals(f.getParameter2());
+		}
+		
+		if (isExecutable) {
+			var root = f.getMathContext();
+			var result = new ObjectArrayList();
+			var mult = new Multiplication(root, new Number(root, 2), f.getParameter1());
+			result.add(mult);
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file
diff --git a/src/main/resources/rules/UndefinedRule1.js b/src/main/resources/rules/UndefinedRule1.js
new file mode 100644
index 00000000..c3db7625
--- /dev/null
+++ b/src/main/resources/rules/UndefinedRule1.js
@@ -0,0 +1,57 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var MathContext = org.warp.picalculator.math.MathContext;
+var Number = org.warp.picalculator.math.functions.Number;
+var Power = org.warp.picalculator.math.functions.Power;
+var Undefined = org.warp.picalculator.math.functions.Undefined;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Undefined rule
+ * 0^0=undefined
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "UndefinedRule1";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.EXISTENCE;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		if (ScriptUtils.instanceOf(f, Power.class)) {
+			var root = f.getMathContext();
+			var fnc = f;
+			if (fnc.getParameter1().equals(new Number(root, 0)) && fnc.getParameter2().equals(new Number(root, 0))) {
+				isExecutable = true;
+			}
+		}
+	
+		if (isExecutable) {
+			var root = f.getMathContext();
+			var result = new ObjectArrayList();
+			result.add(new Undefined(root));
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file
diff --git a/src/main/resources/rules/UndefinedRule2.js b/src/main/resources/rules/UndefinedRule2.js
new file mode 100644
index 00000000..fbecdb0c
--- /dev/null
+++ b/src/main/resources/rules/UndefinedRule2.js
@@ -0,0 +1,60 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var MathContext = org.warp.picalculator.math.MathContext;
+var Division = org.warp.picalculator.math.functions.Division;
+var Number = org.warp.picalculator.math.functions.Number;
+var Undefined = org.warp.picalculator.math.functions.Undefined;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Undefined rule
+ * a / 0 = undefined
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "UndefinedRule2";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.EXISTENCE;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		if (ScriptUtils.instanceOf(f, Division.class)) {
+			var root = f.getMathContext();
+			var fnc = f;
+			if (ScriptUtils.instanceOf(fnc.getParameter2(), Number.class)) {
+				var numb = fnc.getParameter2();
+				if (numb.equals(new Number(root, 0))) {
+					isExecutable = true;
+				}
+			}
+		}
+	
+		if (isExecutable) {
+			var root = f.getMathContext();
+			var result = new ObjectArrayList();
+			result.add(new Undefined(root));
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file
diff --git a/src/main/resources/rules/VariableRule1.js b/src/main/resources/rules/VariableRule1.js
new file mode 100644
index 00000000..d05f56f8
--- /dev/null
+++ b/src/main/resources/rules/VariableRule1.js
@@ -0,0 +1,83 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var FunctionOperator = org.warp.picalculator.math.FunctionOperator;
+var MathContext = org.warp.picalculator.math.MathContext;
+var Multiplication = org.warp.picalculator.math.functions.Multiplication;
+var Subtraction = org.warp.picalculator.math.functions.Subtraction;
+var Sum = org.warp.picalculator.math.functions.Sum;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Variable rule
+ * ax+bx=(a+b)*x (a,b NUMBER; x VARIABLE|MULTIPLICATION)
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "VariableRule1";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.REDUCTION;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		var fnc = f;
+		if (ScriptUtils.instanceOf(f, Subtraction.class) || ScriptUtils.instanceOf(f, Sum.class)) {
+			if (ScriptUtils.instanceOf(fnc.getParameter1(), Multiplication.class) & ScriptUtils.instanceOf(fnc.getParameter2(), Multiplication.class)) {
+				var m1 = fnc.getParameter1();
+				var m2 = fnc.getParameter2();
+				if (m1.getParameter1().equals(m2.getParameter1()) || m1.getParameter2().equals(m2.getParameter2())) {
+					isExecutable = true;
+				}
+			}
+		}
+		
+		if (isExecutable) {
+			var root = fnc.getMathContext();
+			var result = new ObjectArrayList();
+			var m1 = fnc.getParameter1();
+			var m2 = fnc.getParameter2();
+			var a;
+			var b;
+			var x;
+			if (m1.getParameter2().equals(m2.getParameter2())) {
+				x = m1.getParameter2();
+				a = m1.getParameter1();
+				b = m2.getParameter1();
+			} else {
+				x = m1.getParameter1();
+				a = m1.getParameter2();
+				b = m2.getParameter2();
+			}
+	
+			var rets;
+			if (ScriptUtils.instanceOf(fnc, Sum.class)) {
+				rets = new Sum(root, a, b);
+			} else {
+				rets = new Subtraction(root, a, b);
+			}
+			var retm = new Multiplication(root, rets, x);
+			result.add(retm);
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file
diff --git a/src/main/resources/rules/VariableRule2.js b/src/main/resources/rules/VariableRule2.js
new file mode 100644
index 00000000..b96ff723
--- /dev/null
+++ b/src/main/resources/rules/VariableRule2.js
@@ -0,0 +1,72 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var FunctionOperator = org.warp.picalculator.math.FunctionOperator;
+var MathContext = org.warp.picalculator.math.MathContext;
+var Multiplication = org.warp.picalculator.math.functions.Multiplication;
+var Number = org.warp.picalculator.math.functions.Number;
+var Subtraction = org.warp.picalculator.math.functions.Subtraction;
+var Sum = org.warp.picalculator.math.functions.Sum;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Variable rule
+ * ax+x=(a+1)*x (a,b NUMBER; x VARIABLES)
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "VariableRule2";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.REDUCTION;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		var fnc = f;
+		if (ScriptUtils.instanceOf(f, Sum.class) || ScriptUtils.instanceOf(f, Subtraction.class)) {
+			if (ScriptUtils.instanceOf(fnc.getParameter1(), Multiplication.class)) {
+				var m1 = fnc.getParameter1();
+				if (m1.getParameter2().equals(fnc.getParameter2())) {
+					isExecutable = true;
+				}
+			}
+		}
+		
+		if (isExecutable) {
+			var root = fnc.getMathContext();
+			var result = new ObjectArrayList();
+			var m1 = fnc.getParameter1();
+			var a = m1.getParameter1();
+			var x = fnc.getParameter2();
+	
+			var rets;
+			if (ScriptUtils.instanceOf(fnc, Sum.class)) {
+				rets = new Sum(root, a, new Number(root, 1));
+			} else {
+				rets = new Subtraction(root, a, new Number(root, 1));
+			}
+			var retm = new Multiplication(root, rets, x);
+			result.add(retm);
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file
diff --git a/src/main/resources/rules/VariableRule3.js b/src/main/resources/rules/VariableRule3.js
new file mode 100644
index 00000000..89bd7aa9
--- /dev/null
+++ b/src/main/resources/rules/VariableRule3.js
@@ -0,0 +1,73 @@
+//Imports
+
+
+var Error = org.warp.picalculator.Error;
+var Function = org.warp.picalculator.math.Function;
+var FunctionOperator = org.warp.picalculator.math.FunctionOperator;
+var MathContext = org.warp.picalculator.math.MathContext;
+var Multiplication = org.warp.picalculator.math.functions.Multiplication;
+var Number = org.warp.picalculator.math.functions.Number;
+var Subtraction = org.warp.picalculator.math.functions.Subtraction;
+var Sum = org.warp.picalculator.math.functions.Sum;
+
+var ObjectArrayList = Java.type("it.unimi.dsi.fastutil.objects.ObjectArrayList");
+
+/**
+ * Variable rule
+ * x+ax=(a+1)*x (a,b NUMBER; x VARIABLES)
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+var rule = {
+	// Rule name
+	getRuleName: function() {
+		return "VariableRule3";
+	},
+	// Rule type
+	getRuleType: function() {
+		return RuleType.REDUCTION;
+	},
+	/* Rule function
+	   Returns:
+	     - null if it's not executable on the function "f"
+	     - An ObjectArrayList<Function> if it did something
+	*/
+
+	execute: function(f) {
+		var isExecutable;
+		var fnc = f;
+		if (ScriptUtils.instanceOf(f, Sum.class) || ScriptUtils.instanceOf(f, Subtraction.class)) {
+			if (ScriptUtils.instanceOf(fnc.getParameter2(), Multiplication.class)) {
+				var m2 = fnc.getParameter2();
+				if (m2.getParameter2().equals(fnc.getParameter1())) {
+					isExecutable = true;
+				}
+			}
+		}
+		
+		if (isExecutable) {
+			var root = fnc.getMathContext();
+			var result = new ObjectArrayList();
+			var m2 = fnc.getParameter2();
+			var a = m2.getParameter1();
+			var x = fnc.getParameter1();
+	
+			var rets;
+			if (ScriptUtils.instanceOf(fnc, Sum.class)) {
+				rets = new Sum(root, new Number(root, 1), a);
+			} else {
+				rets = new Subtraction(root, new Number(root, 1), a);
+			}
+	
+			var retm = new Multiplication(root, rets, x);
+			result.add(retm);
+			return result;
+		} else {
+			return null;
+		}
+	}
+}
+
+//Add this rule to the list of rules
+RulesManager.addRule(engine.getInterface(rule, Rule.class));
\ No newline at end of file