diff --git a/Algebra Cheat Sheet.rtf b/Algebra Cheat Sheet.rtf
index 4d9f00d3..dd0df088 100644
Binary files a/Algebra Cheat Sheet.rtf and b/Algebra Cheat Sheet.rtf differ
diff --git a/src/org/warp/picalculator/gui/graphicengine/gpu/GPUEngine.java b/src/org/warp/picalculator/gui/graphicengine/gpu/GPUEngine.java
index 7c002011..cb71e2a4 100644
--- a/src/org/warp/picalculator/gui/graphicengine/gpu/GPUEngine.java
+++ b/src/org/warp/picalculator/gui/graphicengine/gpu/GPUEngine.java
@@ -130,7 +130,7 @@ public class GPUEngine implements org.warp.picalculator.gui.graphicengine.Graphi
 		if (!available) {
 			System.err.println(GLProfile.glAvailabilityToString());
 		}
-		return false;
+		return available;
 	}
 
 	@Override
diff --git a/src/org/warp/picalculator/math/functions/Multiplication.java b/src/org/warp/picalculator/math/functions/Multiplication.java
index 1356cd88..38dcefa3 100644
--- a/src/org/warp/picalculator/math/functions/Multiplication.java
+++ b/src/org/warp/picalculator/math/functions/Multiplication.java
@@ -6,6 +6,7 @@ import org.warp.picalculator.Error;
 import org.warp.picalculator.math.Calculator;
 import org.warp.picalculator.math.MathematicalSymbols;
 import org.warp.picalculator.math.rules.ExponentRule15;
+import org.warp.picalculator.math.rules.ExponentRule16;
 import org.warp.picalculator.math.rules.FractionsRule14;
 import org.warp.picalculator.math.rules.NumberRule1;
 import org.warp.picalculator.math.rules.NumberRule2;
@@ -53,6 +54,9 @@ public class Multiplication extends FunctionTwoValues {
 		if (ExponentRule15.compare(this)) {
 			return true;
 		}
+		if (ExponentRule16.compare(this)) {
+			return true;
+		}
 		if (FractionsRule14.compare(this)) {
 			return true;
 		}
@@ -75,6 +79,8 @@ public class Multiplication extends FunctionTwoValues {
 			result = NumberRule6.execute(this);
 		} else if (ExponentRule15.compare(this)) {
 			result = ExponentRule15.execute(this);
+		} else if (ExponentRule16.compare(this)) {
+			result = ExponentRule16.execute(this);
 		} else if (FractionsRule14.compare(this)) {
 			result = FractionsRule14.execute(this);
 		} else if (MultiplicationMethod1.compare(this)) {
diff --git a/src/org/warp/picalculator/math/functions/Power.java b/src/org/warp/picalculator/math/functions/Power.java
index ddec0efa..19938e70 100644
--- a/src/org/warp/picalculator/math/functions/Power.java
+++ b/src/org/warp/picalculator/math/functions/Power.java
@@ -9,6 +9,7 @@ import org.warp.picalculator.math.rules.ExponentRule1;
 import org.warp.picalculator.math.rules.ExponentRule2;
 import org.warp.picalculator.math.rules.ExponentRule3;
 import org.warp.picalculator.math.rules.ExponentRule4;
+import org.warp.picalculator.math.rules.ExponentRule9;
 import org.warp.picalculator.math.rules.FractionsRule4;
 import org.warp.picalculator.math.rules.FractionsRule5;
 import org.warp.picalculator.math.rules.UndefinedRule1;
@@ -49,6 +50,9 @@ public class Power extends FunctionTwoValues {
 		if (ExponentRule4.compare(this)) {
 			return true;
 		}
+		if (ExponentRule9.compare(this)) {
+			return true;
+		}
 		if (FractionsRule4.compare(this)) {
 			return true;
 		}
@@ -84,6 +88,8 @@ public class Power extends FunctionTwoValues {
 			result.addAll(ExponentRule3.execute(this));
 		} else if (ExponentRule4.compare(this)) {
 			result.addAll(ExponentRule4.execute(this));
+		} else if (ExponentRule9.compare(this)) {
+			result.addAll(ExponentRule9.execute(this));
 		} else if (FractionsRule4.compare(this)) {
 			result.addAll(FractionsRule4.execute(this));
 		} else if (FractionsRule5.compare(this)) {
diff --git a/src/org/warp/picalculator/math/rules/ExponentRule16.java b/src/org/warp/picalculator/math/rules/ExponentRule16.java
index 3ddaa7ad..4bede1c6 100644
--- a/src/org/warp/picalculator/math/rules/ExponentRule16.java
+++ b/src/org/warp/picalculator/math/rules/ExponentRule16.java
@@ -9,11 +9,11 @@ import org.warp.picalculator.math.functions.Function;
 import org.warp.picalculator.math.functions.Multiplication;
 import org.warp.picalculator.math.functions.Number;
 import org.warp.picalculator.math.functions.Power;
-import org.warp.picalculator.math.functions.Root;
+import org.warp.picalculator.math.functions.Sum;
 
 /**
  * Exponent rule<br>
- * <b>a√x=x^1/a</b>
+ * <b>(a ^ b) * (a ^ c) = a ^ (b + c)</b>
  * 
  * @author Andrea Cavalli
  *
@@ -21,11 +21,13 @@ import org.warp.picalculator.math.functions.Root;
 public class ExponentRule16 {
 
 	public static boolean compare(Function f) {
-		if (f instanceof Root) {
-			final Root fnc = (Root) f;
-			if (fnc.getVariable1().equals(fnc.getVariable2())) {
-				return true;
-			}
+		final Multiplication fnc = (Multiplication) f;
+		if (fnc.getVariable1() instanceof Power && fnc.getVariable2() instanceof Power) {
+			return ((Power)fnc.getVariable1()).getVariable1().equals(((Power)fnc.getVariable2()).getVariable1());
+		} else if (fnc.getVariable1() instanceof Power) {
+			return ((Power)fnc.getVariable1()).getVariable1().equals(fnc.getVariable2());
+		} else if (fnc.getVariable2() instanceof Power) {
+			return ((Power)fnc.getVariable2()).getVariable1().equals(fnc.getVariable1());
 		}
 		return false;
 	}
@@ -34,14 +36,13 @@ public class ExponentRule16 {
 		final Calculator root = f.getRoot();
 		final ArrayList<Function> result = new ArrayList<>();
 		final Multiplication fnc = (Multiplication) f;
-		final Power p = new Power(fnc.getRoot(), null, null);
-		final Expression expr = new Expression(root);
-		final Function a = fnc.getVariable1();
-		expr.addFunctionToEnd(a);
-		final Number two = new Number(root, 2);
-		p.setVariable1(expr);
-		p.setVariable2(two);
-		result.add(p);
+		if (fnc.getVariable1() instanceof Power && fnc.getVariable2() instanceof Power) {
+			result.add(new Power(root, ((Power)fnc.getVariable1()).getVariable1(), new Sum(root, new Expression(root, ((Power)fnc.getVariable1()).getVariable2()), new Expression(root, ((Power)fnc.getVariable2()).getVariable2()))));
+		} else if (fnc.getVariable1() instanceof Power) {
+			result.add(new Power(root, ((Power)fnc.getVariable1()).getVariable1(), new Sum(root, new Expression(root, ((Power)fnc.getVariable1()).getVariable2()), new Number(root, 1))));
+		} else if (fnc.getVariable2() instanceof Power) {
+			result.add(new Power(root, ((Power)fnc.getVariable1()).getVariable1(), new Sum(root, new Number(root, 1), new Expression(root, ((Power)fnc.getVariable2()).getVariable2()))));
+		}
 		return result;
 	}
 
diff --git a/src/org/warp/picalculator/math/rules/ExponentRule17.java b/src/org/warp/picalculator/math/rules/ExponentRule17.java
new file mode 100644
index 00000000..b10086fd
--- /dev/null
+++ b/src/org/warp/picalculator/math/rules/ExponentRule17.java
@@ -0,0 +1,48 @@
+package org.warp.picalculator.math.rules;
+
+import java.util.ArrayList;
+
+import org.warp.picalculator.Error;
+import org.warp.picalculator.math.Calculator;
+import org.warp.picalculator.math.functions.Expression;
+import org.warp.picalculator.math.functions.Function;
+import org.warp.picalculator.math.functions.Multiplication;
+import org.warp.picalculator.math.functions.Number;
+import org.warp.picalculator.math.functions.Power;
+import org.warp.picalculator.math.functions.Root;
+
+/**
+ * Exponent rule<br>
+ * <b>a√x=x^1/a</b>
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+public class ExponentRule17 {
+
+	public static boolean compare(Function f) {
+		if (f instanceof Root) {
+			final Root fnc = (Root) f;
+			if (fnc.getVariable1().equals(fnc.getVariable2())) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	public static ArrayList<Function> execute(Function f) throws Error {
+		final Calculator root = f.getRoot();
+		final ArrayList<Function> result = new ArrayList<>();
+		final Multiplication fnc = (Multiplication) f;
+		final Power p = new Power(fnc.getRoot(), null, null);
+		final Expression expr = new Expression(root);
+		final Function a = fnc.getVariable1();
+		expr.addFunctionToEnd(a);
+		final Number two = new Number(root, 2);
+		p.setVariable1(expr);
+		p.setVariable2(two);
+		result.add(p);
+		return result;
+	}
+
+}
diff --git a/src/org/warp/picalculator/math/rules/ExponentRule9.java b/src/org/warp/picalculator/math/rules/ExponentRule9.java
new file mode 100644
index 00000000..f27a907c
--- /dev/null
+++ b/src/org/warp/picalculator/math/rules/ExponentRule9.java
@@ -0,0 +1,40 @@
+package org.warp.picalculator.math.rules;
+
+import java.util.ArrayList;
+
+import org.warp.picalculator.Error;
+import org.warp.picalculator.math.Calculator;
+import org.warp.picalculator.math.functions.Expression;
+import org.warp.picalculator.math.functions.Function;
+import org.warp.picalculator.math.functions.Multiplication;
+import org.warp.picalculator.math.functions.Number;
+import org.warp.picalculator.math.functions.Power;
+
+/**
+ * Exponent rule<br>
+ * <b>(a ^ b) ^ c = a ^ (b * c)</b>
+ * 
+ * @author Andrea Cavalli
+ *
+ */
+public class ExponentRule9 {
+
+	public static boolean compare(Function f) {
+		final Power fnc = (Power) f;
+		if (fnc.getVariable1() instanceof Power) {
+			return true;
+		}
+		return false;
+	}
+
+	public static ArrayList<Function> execute(Function f) throws Error {
+		final Calculator root = f.getRoot();
+		final ArrayList<Function> result = new ArrayList<>();
+		final Power powC = (Power) f;
+		final Power powB = (Power) powC.getVariable1();
+		final Power p = new Power(root, powB.getVariable1(), new Multiplication(root, new Expression(root, powB.getVariable2()), new Expression(root, powC.getVariable2())));
+		result.add(p);
+		return result;
+	}
+
+}