diff --git a/src/test/java/no/birkett/kiwi/Tests.java b/src/test/java/no/birkett/kiwi/Tests.java
index 9d88f11..1173ca1 100644
--- a/src/test/java/no/birkett/kiwi/Tests.java
+++ b/src/test/java/no/birkett/kiwi/Tests.java
@@ -15,34 +15,31 @@ public class Tests {
         Variable x = new Variable("x");
 
 
-        solver.addConstraint(Symbolics.equals(Symbolics.add(x,2), 20));
+        solver.addConstraint(Symbolics.equals(Symbolics.add(x, 2), 20));
 
         solver.updateVariables();
 
         assertEquals(x.getValue(), 18, EPSILON);
     }
-    
+
     @Test
     public void simple0() throws UnsatisfiableConstraintException, DuplicateConstraintException {
         Solver solver = new Solver();
         Variable x = new Variable("x");
         Variable y = new Variable("y");
 
-        // x = 20
         solver.addConstraint(Symbolics.equals(x, 20));
 
-        // x + 2 == y + 10
-        //
-        solver.addConstraint(Symbolics.equals(Symbolics.add(x,2), Symbolics.add(y, 10)));
+        solver.addConstraint(Symbolics.equals(Symbolics.add(x, 2), Symbolics.add(y, 10)));
 
         solver.updateVariables();
-        
+
         System.out.println("x " + x.getValue() + " y " + y.getValue());
 
         assertEquals(y.getValue(), 12, EPSILON);
         assertEquals(x.getValue(), 20, EPSILON);
     }
-    
+
     @Test
     public void simple1() throws DuplicateConstraintException, UnsatisfiableConstraintException {
         Variable x = new Variable("x");
@@ -65,7 +62,7 @@ public class Tests {
         solver.addConstraint(Symbolics.equals(y, 10.0).setStrength(Strength.WEAK));
 
         solver.updateVariables();
-        
+
         if (Math.abs(x.getValue() - 10.0) < EPSILON) {
             assertEquals(10, x.getValue(), EPSILON);
             assertEquals(13, y.getValue(), EPSILON);
@@ -75,105 +72,122 @@ public class Tests {
         }
     }
 
-
-    /*@Test
-    public void addDelete1() {
+    @Test
+    public void addDelete1() throws DuplicateConstraintException, UnsatisfiableConstraintException, UnknownConstraintException {
         Variable x = new Variable("x");
         Solver solver = new Solver();
 
-        solver.addConstraint(new Constraint(x, Constraint.Operator.EQ, 100, Strength.WEAK));
+        solver.addConstraint(Symbolics.lessThanOrEqualTo(x, 100).setStrength(Strength.WEAK));
 
-        Constraint c10 = new Constraint(x, Constraint.Operator.LEQ, 10.0);
-        Constraint c20 = new Constraint(x, Constraint.Operator.LEQ, 20.0);
+        solver.updateVariables();
+        assertEquals(100, x.getValue(), EPSILON);
+
+        Constraint c10 = Symbolics.lessThanOrEqualTo(x, 10.0);
+        Constraint c20 = Symbolics.lessThanOrEqualTo(x, 20.0);
 
         solver.addConstraint(c10);
         solver.addConstraint(c20);
 
-        assertEquals(10, x.value(), EPSILON);
+        solver.updateVariables();
+
+        assertEquals(10, x.getValue(), EPSILON);
 
         solver.removeConstraint(c10);
-        assertEquals(20, x.value(), EPSILON);
+
+        solver.updateVariables();
+
+        assertEquals(20, x.getValue(), EPSILON);
 
         solver.removeConstraint(c20);
-        assertEquals(100, x.value(), EPSILON);
+        solver.updateVariables();
 
-        Constraint c10again = new Constraint(x, Constraint.Operator.LEQ, 10.0);
+        assertEquals(100, x.getValue(), EPSILON);
+
+        Constraint c10again = Symbolics.lessThanOrEqualTo(x, 10.0);
 
-        solver.addConstraint(c10);
         solver.addConstraint(c10again);
+        solver.addConstraint(c10);
+        solver.updateVariables();
 
-        assertEquals(10, x.value(), EPSILON);
+        assertEquals(10, x.getValue(), EPSILON);
 
         solver.removeConstraint(c10);
-        assertEquals(10, x.value(), EPSILON);
+        solver.updateVariables();
+        assertEquals(10, x.getValue(), EPSILON);
 
         solver.removeConstraint(c10again);
-        assertEquals(100, x.value(), EPSILON);
+        solver.updateVariables();
+        assertEquals(100, x.getValue(), EPSILON);
     }
 
-
     @Test
-    public void addDelete2() {
+    public void addDelete2() throws DuplicateConstraintException, UnsatisfiableConstraintException, UnknownConstraintException {
         Variable x = new Variable("x");
         Variable y = new Variable("y");
         Solver solver = new Solver();
 
-        solver.addConstraint(new Constraint(x, Constraint.Operator.EQ, 100.0, Strength.WEAK));
-        solver.addConstraint(new Constraint(y, Constraint.Operator.EQ, 120.0, Strength.STRONG));
+        solver.addConstraint(Symbolics.equals(x, 100).setStrength(Strength.WEAK));
+        solver.addConstraint(Symbolics.equals(y, 120).setStrength(Strength.STRONG));
 
-
-        Constraint c10 = new Constraint(x, Constraint.Operator.LEQ, 10.0);
-        Constraint c20 = new Constraint(x, Constraint.Operator.LEQ, 20.0);
+        Constraint c10 = Symbolics.lessThanOrEqualTo(x, 10.0);
+        Constraint c20 = Symbolics.lessThanOrEqualTo(x, 20.0);
 
         solver.addConstraint(c10);
         solver.addConstraint(c20);
+        solver.updateVariables();
 
-        assertEquals(10, x.value(), EPSILON);
-        assertEquals(120, y.value(), EPSILON);
+        assertEquals(10, x.getValue(), EPSILON);
+        assertEquals(120, y.getValue(), EPSILON);
 
         solver.removeConstraint(c10);
-        assertEquals(20, x.value(), EPSILON);
-        assertEquals(120, y.value(), EPSILON);
+        solver.updateVariables();
 
-        Constraint cxy = new Constraint(x.times(2.0), Constraint.Operator.EQ, y);
+        assertEquals(20, x.getValue(), EPSILON);
+        assertEquals(120, y.getValue(), EPSILON);
+
+        Constraint cxy = Symbolics.equals(Symbolics.multiply(x, 2.0), y);
         solver.addConstraint(cxy);
-        assertEquals(20, x.value(), EPSILON);
-        assertEquals(40, y.value(), EPSILON);
+        solver.updateVariables();
+
+        assertEquals(20, x.getValue(), EPSILON);
+        assertEquals(40, y.getValue(), EPSILON);
 
         solver.removeConstraint(c20);
-        assertEquals(60, x.value(), EPSILON);
-        assertEquals(120, y.value(), EPSILON);
+        solver.updateVariables();
+
+        assertEquals(60, x.getValue(), EPSILON);
+        assertEquals(120, y.getValue(), EPSILON);
 
         solver.removeConstraint(cxy);
-        assertEquals(100, x.value(), EPSILON);
-        assertEquals(120, y.value(), EPSILON);
+        solver.updateVariables();
+
+        assertEquals(100, x.getValue(), EPSILON);
+        assertEquals(120, y.getValue(), EPSILON);
     }
 
-
-
-    @Test(expected = RequiredFailure.class)
-    public void inconsistent1() throws InternalError {
+    @Test(expected = UnsatisfiableConstraintException.class)
+    public void inconsistent1() throws InternalError, DuplicateConstraintException, UnsatisfiableConstraintException {
         Variable x = new Variable("x");
         Solver solver = new Solver();
 
-        solver.addConstraint(new Constraint(x, Constraint.Operator.EQ, 10.0));
-        solver.addConstraint(new Constraint(x, Constraint.Operator.EQ, 5.0));
+        solver.addConstraint(Symbolics.equals(x, 10.0));
+        solver.addConstraint(Symbolics.equals(x, 5.0));
+
+        solver.updateVariables();
     }
 
-
-    @Test(expected = RequiredFailure.class)
-    public void inconsistent2() {
+    @Test(expected = UnsatisfiableConstraintException.class)
+    public void inconsistent2() throws DuplicateConstraintException, UnsatisfiableConstraintException {
         Variable x = new Variable("x");
         Solver solver = new Solver();
 
-        solver.addConstraint(new Constraint(x, Constraint.Operator.GEQ, 10.0));
-        solver.addConstraint(new Constraint(x, Constraint.Operator.LEQ, 5.0));
+        solver.addConstraint(Symbolics.greaterThanOrEqualTo(x, 10.0));
+        solver.addConstraint(Symbolics.lessThanOrEqualTo(x, 5.0));
+        solver.updateVariables();
     }
 
-
-
-    @Test(expected = RequiredFailure.class)
-    public void inconsistent3() {
+    @Test(expected = UnsatisfiableConstraintException.class)
+    public void inconsistent3() throws DuplicateConstraintException, UnsatisfiableConstraintException {
 
         Variable w = new Variable("w");
         Variable x = new Variable("x");
@@ -181,12 +195,13 @@ public class Tests {
         Variable z = new Variable("z");
         Solver solver = new Solver();
 
-        solver.addConstraint(new Constraint(w, Constraint.Operator.GEQ, 10.0));
-        solver.addConstraint(new Constraint(x, Constraint.Operator.GEQ, w));
-        solver.addConstraint(new Constraint(y, Constraint.Operator.GEQ, x));
-        solver.addConstraint(new Constraint(z, Constraint.Operator.GEQ, y));
-        solver.addConstraint(new Constraint(z, Constraint.Operator.GEQ, 8.0));
-        solver.addConstraint(new Constraint(z, Constraint.Operator.LEQ, 4.0));
-    }*/
+        solver.addConstraint(Symbolics.greaterThanOrEqualTo(w, 10.0));
+        solver.addConstraint(Symbolics.greaterThanOrEqualTo(x, w));
+        solver.addConstraint(Symbolics.greaterThanOrEqualTo(y, x));
+        solver.addConstraint(Symbolics.greaterThanOrEqualTo(z, y));
+        solver.addConstraint(Symbolics.greaterThanOrEqualTo(z, 8.0));
+        solver.addConstraint(Symbolics.lessThanOrEqualTo(z, 4.0));
+        solver.updateVariables();
+    }
 
 }