diff --git a/package.json b/package.json
index ea2cfad..ed8d860 100644
--- a/package.json
+++ b/package.json
@@ -12,14 +12,11 @@
     "@vaadin/vaadin-charts": "7.0.0",
     "@vaadin/vaadin-combo-box": "5.4.7",
     "@vaadin/vaadin-confirm-dialog": "1.3.0",
-    "@vaadin/vaadin-core-shrinkwrap": "18.0.5",
     "@vaadin/vaadin-custom-field": "1.3.0",
-    "@vaadin/vaadin-date-picker": "4.4.1",
     "@vaadin/vaadin-details": "1.2.0",
     "@vaadin/vaadin-dialog": "2.5.2",
     "@vaadin/vaadin-form-layout": "2.3.0",
     "@vaadin/vaadin-grid": "5.7.7",
-    "@vaadin/vaadin-grid-pro": "2.2.2",
     "@vaadin/vaadin-icons": "4.3.2",
     "@vaadin/vaadin-item": "2.3.0",
     "@vaadin/vaadin-list-box": "1.4.0",
@@ -30,26 +27,12 @@
     "@vaadin/vaadin-ordered-layout": "1.4.0",
     "@vaadin/vaadin-progress-bar": "1.3.0",
     "@vaadin/vaadin-select": "2.4.0",
-    "@vaadin/vaadin-shrinkwrap": "18.0.5",
     "@vaadin/vaadin-split-layout": "4.3.0",
     "@vaadin/vaadin-text-field": "2.8.2",
     "lit-element": "2.3.1",
     "@vaadin/form": "./target/flow-frontend/form",
     "@vaadin/vaadin-avatar": "1.0.3",
-    "open": "^7.2.1",
-    "@vaadin/vaadin-crud": "1.3.0",
-    "@vaadin/vaadin-cookie-consent": "1.2.0",
-    "@vaadin/vaadin-upload": "4.4.1",
-    "@vaadin/vaadin-board": "2.2.0",
-    "@vaadin/vaadin-date-time-picker": "1.4.0",
-    "@vaadin/vaadin-login": "1.2.0",
-    "@vaadin/vaadin-accordion": "1.2.0",
-    "@vaadin/vaadin-checkbox": "2.5.0",
-    "@vaadin/vaadin-time-picker": "2.4.0",
-    "@vaadin/vaadin-context-menu": "4.5.0",
-    "@vaadin/vaadin-tabs": "3.2.0",
-    "@vaadin/vaadin-radio-button": "1.5.1",
-    "@vaadin/vaadin-rich-text-editor": "1.3.0"
+    "open": "^7.2.1"
   },
   "devDependencies": {
     "webpack": "4.42.0",
@@ -84,15 +67,12 @@
       "@vaadin/vaadin-icons": "4.3.2",
       "@vaadin/vaadin-split-layout": "4.3.0",
       "@vaadin/vaadin-combo-box": "5.4.7",
-      "@vaadin/vaadin-core-shrinkwrap": "18.0.5",
       "@vaadin/vaadin-dialog": "2.5.2",
       "@vaadin/vaadin-select": "2.4.0",
       "@vaadin/vaadin-app-layout": "2.2.0",
       "@vaadin/vaadin-item": "2.3.0",
       "@vaadin/vaadin-notification": "1.6.0",
-      "@vaadin/vaadin-grid-pro": "2.2.2",
       "@vaadin/vaadin-progress-bar": "1.3.0",
-      "@vaadin/vaadin-shrinkwrap": "18.0.5",
       "@vaadin/vaadin-ordered-layout": "1.4.0",
       "@vaadin/vaadin-button": "2.4.0",
       "@vaadin/vaadin-text-field": "2.8.2",
@@ -109,21 +89,7 @@
       "@vaadin/vaadin-custom-field": "1.3.0",
       "lit-element": "2.3.1",
       "@vaadin/vaadin-avatar": "1.0.3",
-      "open": "^7.2.1",
-      "@vaadin/vaadin-crud": "1.3.0",
-      "@vaadin/vaadin-cookie-consent": "1.2.0",
-      "@vaadin/vaadin-upload": "4.4.1",
-      "@vaadin/vaadin-board": "2.2.0",
-      "@vaadin/vaadin-charts": "7.0.0",
-      "@vaadin/vaadin-date-time-picker": "1.4.0",
-      "@vaadin/vaadin-login": "1.2.0",
-      "@vaadin/vaadin-date-picker": "4.4.1",
-      "@vaadin/vaadin-accordion": "1.2.0",
-      "@vaadin/vaadin-checkbox": "2.5.0",
-      "@vaadin/vaadin-time-picker": "2.4.0",
-      "@vaadin/vaadin-tabs": "3.2.0",
-      "@vaadin/vaadin-radio-button": "1.5.1",
-      "@vaadin/vaadin-rich-text-editor": "1.3.0"
+      "open": "^7.2.1"
     },
     "devDependencies": {
       "webpack-babel-multi-target-plugin": "2.3.3",
diff --git a/pom.xml b/pom.xml
index 5630b1d..30663be 100644
--- a/pom.xml
+++ b/pom.xml
@@ -75,8 +75,7 @@
     <dependencies>
         <dependency>
             <groupId>com.vaadin</groupId>
-            <!-- Replace artifactId with vaadin-core to use only free components -->
-            <artifactId>vaadin</artifactId>
+            <artifactId>vaadin-core</artifactId>
         </dependency>
         <dependency>
             <groupId>com.vaadin</groupId>
diff --git a/src/main/java/edu/kit/typicalc/model/Tree.java b/src/main/java/edu/kit/typicalc/model/Tree.java
index 7116bb9..d12b300 100644
--- a/src/main/java/edu/kit/typicalc/model/Tree.java
+++ b/src/main/java/edu/kit/typicalc/model/Tree.java
@@ -115,8 +115,7 @@ public class Tree implements TermVisitorTree {
     }
 
     @Override
-    public InferenceStep visit(ConstTerm constTerm, Map<VarTerm,
-            TypeAbstraction> typeAssumptions, Type conclusionType) {
+    public InferenceStep visit(ConstTerm constant, Map<VarTerm, TypeAbstraction> typeAssumptions, Type conclusionType) {
         return null; // TODO
     }
 
diff --git a/src/main/java/edu/kit/typicalc/model/term/AbsTerm.java b/src/main/java/edu/kit/typicalc/model/term/AbsTerm.java
index 36e7da9..5edac46 100644
--- a/src/main/java/edu/kit/typicalc/model/term/AbsTerm.java
+++ b/src/main/java/edu/kit/typicalc/model/term/AbsTerm.java
@@ -51,8 +51,7 @@ public class AbsTerm extends LambdaTerm {
 
 	@Override
 	public InferenceStep accept(TermVisitorTree termVisitorTree, Map<VarTerm, TypeAbstraction> assumptions, Type type) {
-		//todo implement
-		return null;
+		return termVisitorTree.visit(this, assumptions, type);
 	}
 
 	@Override
diff --git a/src/main/java/edu/kit/typicalc/model/term/AppTerm.java b/src/main/java/edu/kit/typicalc/model/term/AppTerm.java
index dddcdd6..d502e08 100644
--- a/src/main/java/edu/kit/typicalc/model/term/AppTerm.java
+++ b/src/main/java/edu/kit/typicalc/model/term/AppTerm.java
@@ -7,20 +7,34 @@ import edu.kit.typicalc.model.type.TypeAbstraction;
 import java.util.Map;
 import java.util.Objects;
 
+/**
+ * Representation of an application term consisting of a function and the parameter passed to it.
+ */
 public class AppTerm extends LambdaTerm {
 	private final LambdaTerm left;
 	private final LambdaTerm right;
 
+	/**
+	 * Initializes a new application term with one lambda term for the function and one lambda term for the parameter.
+	 * @param left the function
+	 * @param right the parameter
+	 */
 	public AppTerm(LambdaTerm left, LambdaTerm right) {
 		this.left = left;
 		this.right = right;
 	}
 
-	public LambdaTerm getLeft() {
+	/**
+	 * @return the function used in this application
+	 */
+	public LambdaTerm getFunction() {
 		return left;
 	}
 
-	public LambdaTerm getRight() {
+	/**
+	 * @return the parameter used in this application
+	 */
+	public LambdaTerm getParameter() {
 		return right;
 	}
 
@@ -36,8 +50,7 @@ public class AppTerm extends LambdaTerm {
 
 	@Override
 	public InferenceStep accept(TermVisitorTree termVisitorTree, Map<VarTerm, TypeAbstraction> assumptions, Type type) {
-		// todo implement
-		return null;
+		return termVisitorTree.visit(this, assumptions, type);
 	}
 
 	@Override
diff --git a/src/main/java/edu/kit/typicalc/model/term/BooleanTerm.java b/src/main/java/edu/kit/typicalc/model/term/BooleanTerm.java
index d605975..a61ae72 100644
--- a/src/main/java/edu/kit/typicalc/model/term/BooleanTerm.java
+++ b/src/main/java/edu/kit/typicalc/model/term/BooleanTerm.java
@@ -1,12 +1,34 @@
 package edu.kit.typicalc.model.term;
 
+import edu.kit.typicalc.model.type.NamedType;
+import edu.kit.typicalc.model.type.Type;
+
+/**
+ * Representation of a constant boolean lambda term: either false or true.
+ */
 public class BooleanTerm extends ConstTerm {
+	private final boolean value;
+
+	/**
+	 * Initializes a new boolean lambda term with the given value.
+	 * @param value true or false
+	 */
 	public BooleanTerm(boolean value) {
-		// TODO
+		this.value = value;
+	}
+
+	@Override
+	public NamedType getType() {
+		return NamedType.BOOLEAN;
 	}
 
 	@Override
 	public boolean hasLet() {
 		return false;
 	}
+
+	@Override
+	public String toString() {
+		return Boolean.toString(value);
+	}
 }
diff --git a/src/main/java/edu/kit/typicalc/model/term/ConstTerm.java b/src/main/java/edu/kit/typicalc/model/term/ConstTerm.java
index 68aa292..c4823d0 100644
--- a/src/main/java/edu/kit/typicalc/model/term/ConstTerm.java
+++ b/src/main/java/edu/kit/typicalc/model/term/ConstTerm.java
@@ -1,12 +1,21 @@
 package edu.kit.typicalc.model.term;
 
 import edu.kit.typicalc.model.step.InferenceStep;
+import edu.kit.typicalc.model.type.NamedType;
 import edu.kit.typicalc.model.type.Type;
 import edu.kit.typicalc.model.type.TypeAbstraction;
 
 import java.util.Map;
 
-public class ConstTerm extends LambdaTerm {
+/**
+ * Abstract representation of a constant lambda term that has a predetermined type and a value of that type.
+ */
+public abstract class ConstTerm extends LambdaTerm {
+	/**
+	 * @return the named type of the constant
+	 */
+	public abstract NamedType getType();
+
 	@Override
 	public boolean hasLet() {
 		return false;
@@ -18,8 +27,7 @@ public class ConstTerm extends LambdaTerm {
 	}
 
 	@Override
-	public InferenceStep accept(TermVisitorTree termVisitorTree, Map<VarTerm, TypeAbstraction> assumptions, Type type) {
-		// todo implment
-		return null;
+	public InferenceStep accept(TermVisitorTree visitor, Map<VarTerm, TypeAbstraction> assumptions, Type type) {
+		return visitor.visit(this, assumptions, type);
 	}
 }
diff --git a/src/main/java/edu/kit/typicalc/model/term/IntegerTerm.java b/src/main/java/edu/kit/typicalc/model/term/IntegerTerm.java
index 5cb35f8..fabfc1d 100644
--- a/src/main/java/edu/kit/typicalc/model/term/IntegerTerm.java
+++ b/src/main/java/edu/kit/typicalc/model/term/IntegerTerm.java
@@ -1,7 +1,28 @@
 package edu.kit.typicalc.model.term;
 
+import edu.kit.typicalc.model.type.NamedType;
+
+/**
+ * Representation of a constant integer lambda term: e.g. -1, 0 or 16.
+ */
 public class IntegerTerm extends ConstTerm {
+	private final int value;
+
+	/**
+	 * Initializes a new integer lambda term with the given value.
+	 * @param value an integer
+	 */
 	public IntegerTerm(int value) {
-		// TODO
+		this.value = value;
+	}
+
+	@Override
+	public NamedType getType() {
+		return NamedType.INT;
+	}
+
+	@Override
+	public String toString() {
+		return Integer.toString(value);
 	}
 }
diff --git a/src/main/java/edu/kit/typicalc/model/term/LambdaTerm.java b/src/main/java/edu/kit/typicalc/model/term/LambdaTerm.java
index 2ef8c5c..ec7c03b 100644
--- a/src/main/java/edu/kit/typicalc/model/term/LambdaTerm.java
+++ b/src/main/java/edu/kit/typicalc/model/term/LambdaTerm.java
@@ -6,6 +6,11 @@ import edu.kit.typicalc.model.type.TypeAbstraction;
 
 import java.util.Map;
 
+/**
+ * Abstract representation of a lambda term.
+ * Depending on the subclass used, a lambda term may contain several other lambda terms
+ * and thus form a tree-like structure of lambda terms.
+ */
 public abstract class LambdaTerm {
 	/**
 	 * @return whether the lambda term contains a let expression
@@ -18,6 +23,13 @@ public abstract class LambdaTerm {
 	 */
 	public abstract void accept(TermVisitor termVisitor);
 
+	/**
+	 * Uses exactly one method of the visitor and provides the arguments passed.
+	 * @param termVisitorTree the visitor
+	 * @param assumptions type assumptions
+	 * @param type a type
+	 * @return the result returned by the visitor
+	 */
     public abstract InferenceStep accept(TermVisitorTree termVisitorTree,
                                          Map<VarTerm, TypeAbstraction> assumptions, Type type);
 
diff --git a/src/main/java/edu/kit/typicalc/model/term/LetTerm.java b/src/main/java/edu/kit/typicalc/model/term/LetTerm.java
index fb1b1a1..8cf3fd2 100644
--- a/src/main/java/edu/kit/typicalc/model/term/LetTerm.java
+++ b/src/main/java/edu/kit/typicalc/model/term/LetTerm.java
@@ -6,8 +6,25 @@ import edu.kit.typicalc.model.type.TypeAbstraction;
 
 import java.util.Map;
 
+/**
+ * Representation of a let term with its variable, the lambda term assigned
+ * to this variable and the lambda term the variable is used in.
+ */
 public class LetTerm extends LambdaTerm {
-	public LetTerm(VarTerm var, LambdaTerm def, LambdaTerm body) {
+	private final VarTerm variable;
+	private final LambdaTerm definition;
+	private final LambdaTerm body;
+
+	/**
+	 * Initializes a new let term with its variable and two lambda terms.
+	 * @param variable the variable of the let term
+	 * @param definition the lambda term assigned to the variable
+	 * @param body the lambda term the variable may be used in
+	 */
+	public LetTerm(VarTerm variable, LambdaTerm definition, LambdaTerm body) {
+		this.variable = variable;
+		this.definition = definition;
+		this.body = body;
 	}
 
 	@Override
@@ -21,8 +38,28 @@ public class LetTerm extends LambdaTerm {
 	}
 
 	@Override
-	public InferenceStep accept(TermVisitorTree termVisitorTree, Map<VarTerm, TypeAbstraction> assumptions, Type type) {
-		//todo implement
-		return null;
+	public InferenceStep accept(TermVisitorTree visitor, Map<VarTerm, TypeAbstraction> assumptions, Type type) {
+		return visitor.visit(this, assumptions, type);
+	}
+
+	/**
+	 * @return the variable defined in this let expression
+	 */
+	public VarTerm getVariable() {
+		return variable;
+	}
+
+	/**
+	 * @return definition of the variable
+	 */
+	public LambdaTerm getVariableDefinition() {
+		return definition;
+	}
+
+	/**
+	 * @return the inner lambda term (where the variable is used)
+	 */
+	public LambdaTerm getInner() {
+		return body;
 	}
 }
diff --git a/src/main/java/edu/kit/typicalc/model/term/VarTerm.java b/src/main/java/edu/kit/typicalc/model/term/VarTerm.java
index 75ab5ca..635ce99 100644
--- a/src/main/java/edu/kit/typicalc/model/term/VarTerm.java
+++ b/src/main/java/edu/kit/typicalc/model/term/VarTerm.java
@@ -7,14 +7,28 @@ import edu.kit.typicalc.model.type.TypeAbstraction;
 import java.util.Map;
 import java.util.Objects;
 
+/**
+ * Representation of a variable term with its name.
+ */
 public class VarTerm extends LambdaTerm {
 	private final String name;
 
+	/**
+	 * Initializes a new variable term with its name.
+	 * @param name the name of the variable
+	 */
 	public VarTerm(String name) {
 		super();
 		this.name = name;
 	}
 
+	/**
+	 * @return the name of this variable
+	 */
+	public String getName() {
+		return name;
+	}
+
 	@Override
 	public boolean hasLet() {
 		return false;
@@ -26,9 +40,8 @@ public class VarTerm extends LambdaTerm {
 	}
 
 	@Override
-	public InferenceStep accept(TermVisitorTree termVisitorTree, Map<VarTerm, TypeAbstraction> assumptions, Type type) {
-		//todo implement
-		return null;
+	public InferenceStep accept(TermVisitorTree visitor, Map<VarTerm, TypeAbstraction> assumptions, Type type) {
+		return visitor.visit(this, assumptions, type);
 	}
 
 	@Override
diff --git a/src/main/java/edu/kit/typicalc/model/type/NamedType.java b/src/main/java/edu/kit/typicalc/model/type/NamedType.java
new file mode 100644
index 0000000..66f4099
--- /dev/null
+++ b/src/main/java/edu/kit/typicalc/model/type/NamedType.java
@@ -0,0 +1,10 @@
+package edu.kit.typicalc.model.type;
+
+public class NamedType extends Type {
+	public static final NamedType BOOLEAN = new NamedType("boolean");
+	public static final NamedType INT = new NamedType("int");
+
+	public NamedType(String name) {
+		// TODO
+	}
+}