diff --git a/pmd-java/src/test/java/net/sourceforge/pmd/typeresolution/TypeInferenceTest.java b/pmd-java/src/test/java/net/sourceforge/pmd/typeresolution/TypeInferenceTest.java
index 4d1f1011bf..ed31b98676 100644
--- a/pmd-java/src/test/java/net/sourceforge/pmd/typeresolution/TypeInferenceTest.java
+++ b/pmd-java/src/test/java/net/sourceforge/pmd/typeresolution/TypeInferenceTest.java
@@ -30,8 +30,10 @@ public class TypeInferenceTest {
     private JavaTypeDefinition integer = JavaTypeDefinition.forClass(Integer.class);
     private JavaTypeDefinition primitiveInt = JavaTypeDefinition.forClass(int.class);
     private JavaTypeDefinition generic = JavaTypeDefinition.forClass(Map.class, number, integer);
-    private Variable a = new Variable();
-    private Variable b = new Variable();
+    private Variable alpha = new Variable();
+    private Variable beta = new Variable();
+    JavaTypeDefinition s = JavaTypeDefinition.forClass(int.class);
+    JavaTypeDefinition t = JavaTypeDefinition.forClass(double.class);
 
     @Test
     public void testEqualityReduceProperVsProper() {
@@ -47,22 +49,22 @@ public class TypeInferenceTest {
     public void testEqualityReduceVariableVsNotPrimitive() {
         // Otherwise, if S is an inference variable, α, and T is not a primitive type, the constraint reduces to
         // the bound α = T.
-        List<BoundOrConstraint> result = new Constraint(a, number, EQUALITY).reduce();
+        List<BoundOrConstraint> result = new Constraint(alpha, number, EQUALITY).reduce();
         assertEquals(result.size(), 1);
-        testBoundOrConstraint(result.get(0), a, number, EQUALITY, Bound.class);
+        testBoundOrConstraint(result.get(0), alpha, number, EQUALITY, Bound.class);
     }
 
     @Test
     public void testEqualityReduceNotPrimitiveVsVariable() {
         // Otherwise, if T is an inference variable, α, and S is not a primitive type, the constraint reduces
         // to the bound S = α.
-        List<BoundOrConstraint> result = new Constraint(number, a, EQUALITY).reduce();
+        List<BoundOrConstraint> result = new Constraint(number, alpha, EQUALITY).reduce();
         assertEquals(result.size(), 1);
-        testBoundOrConstraint(result.get(0), number, a, EQUALITY, Bound.class);
+        testBoundOrConstraint(result.get(0), number, alpha, EQUALITY, Bound.class);
 
-        result = new Constraint(a, b, EQUALITY).reduce();
+        result = new Constraint(alpha, beta, EQUALITY).reduce();
         assertEquals(result.size(), 1);
-        testBoundOrConstraint(result.get(0), a, b, EQUALITY, Bound.class);
+        testBoundOrConstraint(result.get(0), alpha, beta, EQUALITY, Bound.class);
     }
 
     @Test
@@ -80,7 +82,8 @@ public class TypeInferenceTest {
     public void testEqualityReduceArrayTypes() {
         // Otherwise, if S and T are array types, S'[] and T'[], the constraint reduces to ‹S' = T'›.
         List<BoundOrConstraint> result = new Constraint(JavaTypeDefinition.forClass(Number[].class),
-                                                        JavaTypeDefinition.forClass(Integer[].class), EQUALITY).reduce();
+                                                        JavaTypeDefinition.forClass(Integer[].class), EQUALITY)
+                .reduce();
         assertEquals(result.size(), 1);
         testBoundOrConstraint(result.get(0), number, integer, EQUALITY, Constraint.class);
     }
@@ -105,21 +108,21 @@ public class TypeInferenceTest {
     @Test
     public void testSubtypeReduceVariableVsAny() {
         // Otherwise, if S is an inference variable, α, the constraint reduces to the bound α <: T.
-        List<BoundOrConstraint> result = new Constraint(a, integer, SUBTYPE).reduce();
+        List<BoundOrConstraint> result = new Constraint(alpha, integer, SUBTYPE).reduce();
         assertEquals(result.size(), 1);
-        testBoundOrConstraint(result.get(0), a, integer, SUBTYPE, Bound.class);
+        testBoundOrConstraint(result.get(0), alpha, integer, SUBTYPE, Bound.class);
     }
 
     @Test
     public void testSubtypeReduceAnyVsVariable() {
         // Otherwise, if T is an inference variable, α, the constraint reduces to the bound S <: α.
-        List<BoundOrConstraint> result = new Constraint(integer, a, SUBTYPE).reduce();
+        List<BoundOrConstraint> result = new Constraint(integer, alpha, SUBTYPE).reduce();
         assertEquals(result.size(), 1);
-        testBoundOrConstraint(result.get(0), integer, a, SUBTYPE, Bound.class);
+        testBoundOrConstraint(result.get(0), integer, alpha, SUBTYPE, Bound.class);
 
-        result = new Constraint(a, b, SUBTYPE).reduce();
+        result = new Constraint(alpha, beta, SUBTYPE).reduce();
         assertEquals(result.size(), 1);
-        testBoundOrConstraint(result.get(0), a, b, SUBTYPE, Bound.class);
+        testBoundOrConstraint(result.get(0), alpha, beta, SUBTYPE, Bound.class);
     }
 
 
@@ -167,13 +170,13 @@ public class TypeInferenceTest {
     @Test
     public void testLooseInvocationAnythingElse() {
         // Otherwise, the constraint reduces to ‹S<:T›.
-        List<BoundOrConstraint> result = new Constraint(number, a, LOOSE_INVOCATION).reduce();
+        List<BoundOrConstraint> result = new Constraint(number, alpha, LOOSE_INVOCATION).reduce();
         assertEquals(result.size(), 1);
-        testBoundOrConstraint(result.get(0), number, a, SUBTYPE, Constraint.class);
+        testBoundOrConstraint(result.get(0), number, alpha, SUBTYPE, Constraint.class);
 
-        result = new Constraint(a, number, LOOSE_INVOCATION).reduce();
+        result = new Constraint(alpha, number, LOOSE_INVOCATION).reduce();
         assertEquals(result.size(), 1);
-        testBoundOrConstraint(result.get(0), a, number, SUBTYPE, Constraint.class);
+        testBoundOrConstraint(result.get(0), alpha, number, SUBTYPE, Constraint.class);
     }
 
     @Test
@@ -198,14 +201,8 @@ public class TypeInferenceTest {
     }
 
     @Test
-    public void testIncorporation() {
+    public void testIncorporationEqualityAndEquality() {
         List<Constraint> result;
-        List<Bound> current = new ArrayList<>();
-        List<Bound> newBounds = new ArrayList<>();
-
-        JavaTypeDefinition s = JavaTypeDefinition.forClass(int.class);
-        JavaTypeDefinition t = JavaTypeDefinition.forClass(double.class);
-        Variable alpha = a;
 
         // ### Original rule 1. : α = S and α = T imply ‹S = T›
         result = incorporationResult(new Bound(alpha, s, EQUALITY), new Bound(alpha, t, EQUALITY));
@@ -226,7 +223,11 @@ public class TypeInferenceTest {
         result = incorporationResult(new Bound(s, alpha, EQUALITY), new Bound(t, alpha, EQUALITY));
         assertEquals(result.size(), 1);
         testBoundOrConstraint(result.get(0), s, t, EQUALITY, Constraint.class);
+    }
 
+    @Test
+    public void testIncorporationEqualityAndSubtypeLeftVariable() {
+        List<Constraint> result;
 
         // ### Original rule 2. : α = S and α <: T imply ‹S <: T›
         result = incorporationResult(new Bound(alpha, s, EQUALITY), new Bound(alpha, t, SUBTYPE));
@@ -247,7 +248,11 @@ public class TypeInferenceTest {
         result = incorporationResult(new Bound(alpha, t, SUBTYPE), new Bound(s, alpha, EQUALITY));
         assertEquals(result.size(), 1);
         testBoundOrConstraint(result.get(0), s, t, SUBTYPE, Constraint.class);
+    }
 
+    @Test
+    public void testIncorporationEqualityAndSubtypeRightVariable() {
+        List<Constraint> result;
 
         // ### Original rule 3. : α = S and T <: α imply ‹T <: S›
         result = incorporationResult(new Bound(alpha, s, EQUALITY), new Bound(t, alpha, SUBTYPE));
@@ -268,8 +273,12 @@ public class TypeInferenceTest {
         result = incorporationResult(new Bound(t, alpha, SUBTYPE), new Bound(s, alpha, EQUALITY));
         assertEquals(result.size(), 1);
         testBoundOrConstraint(result.get(0), t, s, SUBTYPE, Constraint.class);
+    }
 
-
+    @Test
+    public void testIncorporationSubtypeAndSubtype() {
+        List<Constraint> result;
+        
         // ### Original rule 4. : S <: α and α <: T imply ‹S <: T›
         result = incorporationResult(new Bound(s, alpha, EQUALITY), new Bound(alpha, t, SUBTYPE));
         assertEquals(result.size(), 1);