diff --git a/src/main/java/jobshop/BestKnownResults.java b/src/main/java/jobshop/BestKnownResults.java
index 31949a5..77717ec 100644
--- a/src/main/java/jobshop/BestKnownResults.java
+++ b/src/main/java/jobshop/BestKnownResults.java
@@ -15,7 +15,7 @@ public class BestKnownResults {
     /**
      * Checks whether we have data available for the provided instance.
      * @param instanceName Name of the instance.
-     * @return True if the isntance is known, false otherwise.
+     * @return True if the instance is known, false otherwise.
      */
     public static boolean isKnown(String instanceName) {
         return bests.containsKey(instanceName);
diff --git a/src/main/java/jobshop/Main.java b/src/main/java/jobshop/Main.java
index f0f9663..be17c5e 100644
--- a/src/main/java/jobshop/Main.java
+++ b/src/main/java/jobshop/Main.java
@@ -5,12 +5,10 @@ import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.HashMap;
 import java.util.List;
 import java.util.stream.Collectors;
 
 import jobshop.solvers.*;
-import jobshop.solvers.neighborhood.Nowicki;
 import net.sourceforge.argparse4j.ArgumentParsers;
 import net.sourceforge.argparse4j.inf.ArgumentParser;
 import net.sourceforge.argparse4j.inf.ArgumentParserException;
diff --git a/src/main/java/jobshop/encodings/JobNumbers.java b/src/main/java/jobshop/encodings/JobNumbers.java
index d29df37..957c4cf 100644
--- a/src/main/java/jobshop/encodings/JobNumbers.java
+++ b/src/main/java/jobshop/encodings/JobNumbers.java
@@ -16,6 +16,7 @@ public class JobNumbers extends Encoding {
      * element of `jobs` that has not been set yet. */
     public int nextToSet = 0;
 
+    /** Creates a new empty encoding. */
     public JobNumbers(Instance instance) {
         super(instance);
 
@@ -23,6 +24,7 @@ public class JobNumbers extends Encoding {
         Arrays.fill(jobs, -1);
     }
 
+    /** Cerates a new encoding based on the given schedule. */
     public JobNumbers(Schedule schedule) {
         super(schedule.instance);
 
@@ -48,6 +50,7 @@ public class JobNumbers extends Encoding {
         }
     }
 
+    /** Schedule the next task of the given job. */
     public void addTask(int jobNumber) {
         this.jobs[nextToSet++] = jobNumber;
     }
diff --git a/src/main/java/jobshop/encodings/ResourceOrder.java b/src/main/java/jobshop/encodings/ResourceOrder.java
index f13a84c..556a51e 100644
--- a/src/main/java/jobshop/encodings/ResourceOrder.java
+++ b/src/main/java/jobshop/encodings/ResourceOrder.java
@@ -10,10 +10,10 @@ public class ResourceOrder extends Encoding {
 
     // for each machine m, taskByMachine[m] is an array of tasks to be
     // executed on this machine in the same order
-    public final Task[][] tasksByMachine;
+    final Task[][] tasksByMachine;
 
     // for each machine, indicate how many tasks have been initialized
-    public final int[] nextFreeSlot;
+    final int[] nextFreeSlot;
 
     /** Creates a new empty resource order. */
     public ResourceOrder(Instance instance)
@@ -51,6 +51,8 @@ public class ResourceOrder extends Encoding {
         }
     }
 
+    /** Enqueues a task for the given job on the machine. We automatically, find the task
+     * that must be executed on this particular machine. */
     public void addToMachine(int machine, int jobNumber) {
         addTaskToMachine(machine, new Task(jobNumber, instance.task_with_machine(jobNumber, machine)));
     }
@@ -60,10 +62,16 @@ public class ResourceOrder extends Encoding {
         nextFreeSlot[machine] += 1;
     }
 
-    public void swapTasks(int machine, int indexFirstTask, int indexSecondTask) {
-        Task tmp = tasksByMachine[machine][indexFirstTask];
-        tasksByMachine[machine][indexFirstTask] = tasksByMachine[machine][indexSecondTask];
-        tasksByMachine[machine][indexSecondTask] = tmp;
+    /** Exchange the order of two tasks that are scheduled on a given machine.
+     *
+     * @param machine Machine on which the two tasks appear (line on which to perform the exchange)
+     * @param indexTask1 Position of the first task on the machine (column of the first element)
+     * @param indexTask2 Position of the second task on the machine (column of the second element)
+     */
+    public void swapTasks(int machine, int indexTask1, int indexTask2) {
+        Task tmp = tasksByMachine[machine][indexTask1];
+        tasksByMachine[machine][indexTask1] = tasksByMachine[machine][indexTask2];
+        tasksByMachine[machine][indexTask2] = tmp;
     }
 
     @Override
diff --git a/src/main/java/jobshop/encodings/Schedule.java b/src/main/java/jobshop/encodings/Schedule.java
index 0507855..29be765 100644
--- a/src/main/java/jobshop/encodings/Schedule.java
+++ b/src/main/java/jobshop/encodings/Schedule.java
@@ -69,8 +69,8 @@ public class Schedule extends Encoding {
                 for(int j2 = j1+1; j2< instance.numJobs ; j2++) {
                     int t2 = instance.task_with_machine(j2, machine);
 
-                    boolean t1_first = startTime(j1, t1) + instance.duration(j1, t1) <= startTime(j2, t2);
-                    boolean t2_first = startTime(j2, t2) + instance.duration(j2, t2) <= startTime(j1, t1);
+                    boolean t1_first = endTime(j1, t1) <= startTime(j2, t2);
+                    boolean t2_first = endTime(j2, t2) <= startTime(j1, t1);
 
                     if(!t1_first && !t2_first)
                         return false;
diff --git a/src/main/java/jobshop/solvers/BasicSolver.java b/src/main/java/jobshop/solvers/BasicSolver.java
index 2f9cce6..9695e33 100644
--- a/src/main/java/jobshop/solvers/BasicSolver.java
+++ b/src/main/java/jobshop/solvers/BasicSolver.java
@@ -5,8 +5,7 @@ import jobshop.Result;
 import jobshop.encodings.JobNumbers;
 
 /**
- * A very naïve solver that first schedules
- *
+ * A very naïve solver that first schedules all first tasks, then all second tasks, ...
  **/
 public class BasicSolver implements Solver {
     @Override
diff --git a/src/main/java/jobshop/solvers/RandomSolver.java b/src/main/java/jobshop/solvers/RandomSolver.java
index 8fc2100..f531441 100644
--- a/src/main/java/jobshop/solvers/RandomSolver.java
+++ b/src/main/java/jobshop/solvers/RandomSolver.java
@@ -6,6 +6,9 @@ import jobshop.encodings.Schedule;
 
 import java.util.Random;
 
+/** A solver that generates random solutions until a deadline is met.
+ *  Then returns the best solution that was generated.
+ */
 public class RandomSolver implements Solver {
 
     @Override
diff --git a/src/main/java/jobshop/solvers/neighborhood/Neighbor.java b/src/main/java/jobshop/solvers/neighborhood/Neighbor.java
index 9380ab0..7faf2f2 100644
--- a/src/main/java/jobshop/solvers/neighborhood/Neighbor.java
+++ b/src/main/java/jobshop/solvers/neighborhood/Neighbor.java
@@ -1,8 +1,15 @@
 package jobshop.solvers.neighborhood;
 
-public abstract class Neighbor<Encoding> {
+import jobshop.encodings.Encoding;
 
-    public abstract void applyOn(Encoding current);
-    public abstract void undoApplyOn(Encoding current);
+/** This class provides a representation of neighbor by allowing to transform
+ * a solution in a particular encoding Enc into the neighbor and back.*/
+public abstract class Neighbor<Enc extends Encoding> {
+
+    /** Transform the given solution into the neighbor. */
+    public abstract void applyOn(Enc current);
+
+    /** Transform the neighbor back into the original solution. */
+    public abstract void undoApplyOn(Enc current);
 
 }
diff --git a/src/main/java/jobshop/solvers/neighborhood/Neighborhood.java b/src/main/java/jobshop/solvers/neighborhood/Neighborhood.java
index cb9f562..285b0ac 100644
--- a/src/main/java/jobshop/solvers/neighborhood/Neighborhood.java
+++ b/src/main/java/jobshop/solvers/neighborhood/Neighborhood.java
@@ -1,9 +1,17 @@
 package jobshop.solvers.neighborhood;
 
+import jobshop.encodings.Encoding;
+
 import java.util.List;
 
-public abstract class Neighborhood<Encoding> {
+/** For a particular encoding Enc, a neighborhood allow the generation of the neighbors of
+ * a particular solution.
+ *
+ * @param <Enc> A subcless of Encoding for which this encoding can generate neighbors.
+ */
+public abstract class Neighborhood<Enc extends Encoding> {
 
-    public abstract List<Neighbor<Encoding>> generateNeighbors(Encoding current);
+    /** Generates all neighbors for the current solution.  */
+    public abstract List<Neighbor<Enc>> generateNeighbors(Enc current);
 
 }
diff --git a/src/main/java/jobshop/solvers/neighborhood/Nowicki.java b/src/main/java/jobshop/solvers/neighborhood/Nowicki.java
index eb2e109..8ee97ec 100644
--- a/src/main/java/jobshop/solvers/neighborhood/Nowicki.java
+++ b/src/main/java/jobshop/solvers/neighborhood/Nowicki.java
@@ -5,6 +5,13 @@ import jobshop.encodings.ResourceOrder;
 import java.util.ArrayList;
 import java.util.List;
 
+/** Implementation of the Nowicki and Smutnicki neighborhood.
+ *
+ * It works on the ResourceOrder encoding by generating two neighbors for each block
+ * of the critical path.
+ * For each block, two neighbors should be generated that respectivly swap the first two and
+ * last two tasks of the block.
+ */
 public class Nowicki extends Neighborhood<ResourceOrder> {
 
     /** A block represents a subsequence of the critical path such that all tasks in it execute on the same machine.