Added a FeasibleCycleInspector and corresponding tests.

Also relocated minInnerDelay/maxInnerDelay methods for better clarity.

src/main/java/graphgen/generator/components/properties/minII/MinIICycleInspector.java

+/*
+ * Copyright 2018 Sebastian Vollbrecht, Julian Oppermann
+ * Embedded Systems and Applications Group, TU Darmstadt
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package graphgen.generator.components.properties.minII;
+
+import graphgen.graph.LayerStructure;
+import graphgen.graph.ResourceNode;
+
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * An abstract base class for analyzing created graphs regarding MinII-specific cycles.
+ *
+ * @author Sebastian Vollbrecht
+ */
+public abstract class MinIICycleInspector {
+
+	protected final LayerStructure layers;
+	protected final Set<ResourceNode> nodes;
+
+	protected MinIICycleInspector(LayerStructure layers, Set<ResourceNode> nodes) {
+		this.layers = Objects.requireNonNull(layers);
+		this.nodes = Objects.requireNonNull(nodes);
+	}
+
+	/**
+	 * Returns the minimum inner delay which a cycle induced by the given arguments can have. The implementing classes
+	 * are required to return a minimum inner delay such that a delay which is less than the returned delay would lead
+	 * to one of the following problems:<ul><li>it would result in a MinII smaller than specified</li><li>it would not
+	 * meet the implementing class's purpose (e.g. it would be impossible to ensure an infeasibility, ...)
+	 *
+	 * @param minII            the MinII to ensure
+	 * @param backedgeDelay    the delay of the backedge(s) which will <i>close</i> the cycle
+	 * @param backedgeDistance the distance of the backedge(s) which will <i>close</i> the cycle
+	 * @return the cycle's minimum inner delay adhering to the above-mentioned requirements
+	 */
+	public abstract int getMinInnerDelay(int minII, int backedgeDelay, int backedgeDistance);
+
+	/**
+	 * Returns the maximum inner delay which a cycle induced by the given arguments can have. The implementing classes
+	 * are required to return a maximum inner delay such that a delay which is greater than the returned delay would
+	 * lead to one of the following problems:<ul><li>it would result in a MinII greater than specified</li><li>it would
+	 * not meet the implementing class's purpose.
+	 *
+	 * @param minII            the MinII to ensure
+	 * @param backedgeDelay    the delay of the backedge(s) which will <i>close</i> the cycle
+	 * @param backedgeDistance the distance of the backedge(s) which will <i>close</i> the cycle
+	 * @return the cycle's maximum inner delay adhering to the above-mentioned requirements
+	 */
+	public abstract int getMaxInnerDelay(int minII, int backedgeDelay, int backedgeDistance);
+
+	/**
+	 * Returns the minimum inner delay which a cycle containing backedges with the specified parameters can have without
+	 * falling below the given MinII.
+	 * <p>
+	 * It is the lower bound of the RecMinII formula's ceiling function and can be retrieved like so:
+	 * <pre>RecMinII = ceil((minInnerDelay + backedgeDelay) / backedgeDistance)</pre>
+	 * It follows that
+	 * <pre>(minInnerDelay + backedgeDelay) / backedgeDistance > RecMinII - 1</pre>
+	 * and
+	 * <pre>minInnerDelay > backedgeDistance * (RecMinII - 1) - backedgeDelay</pre><p>
+	 * Because the inner delay is an integer value, the smallest possible value which still fulfills the inequality is
+	 * the result of adding 1 to the right-hand side.
+	 *
+	 * @throws IllegalArgumentException if the MinII is not positive, if the delay is negative or if the distance is not
+	 *                                  positive
+	 */
+	public static int minInnerDelay(int minII, int backedgeDelay, int backedgeDistance) {
+		if (minII <= 0) {
+			throw new IllegalArgumentException("MinII must be positive.");
+		} else if (backedgeDelay < 0) {
+			throw new IllegalArgumentException("Backedge delay cannot be negative.");
+		} else if (backedgeDistance <= 0) {
+			throw new IllegalArgumentException("Backedge distance must be positive.");
+		}
+		return Math.max(0, backedgeDistance * (minII - 1) - backedgeDelay + 1);
+	}
+
+	/**
+	 * Returns the maximum inner delay which a cycle containing backedges with the specified parameters can have without
+	 * exceeding the given MinII.
+	 * <p>
+	 * It can be derived from the RecMinII formula:
+	 * <pre>RecMinII = ceil((maxInnerDelay + backedgeDelay) / backedgeDistance)</pre>
+	 * It follows that
+	 * <pre>RecMinII * backedgeDistance = maxInnerDelay + backedgeDelay</pre>
+	 * and
+	 * <pre>RecMinII * backedgeDistance - backedgeDelay = maxInnerDelay</pre>
+	 *
+	 * @throws IllegalArgumentException if the MinII is not positive, if the delay is negative or if the distance is not
+	 *                                  positive
+	 */
+	public static int maxInnerDelay(int minII, int backedgeDelay, int backedgeDistance) {
+		if (minII <= 0) {
+			throw new IllegalArgumentException("MinII must be positive.");
+		} else if (backedgeDelay < 0) {
+			throw new IllegalArgumentException("Backedge delay cannot be negative.");
+		} else if (backedgeDistance <= 0) {
+			throw new IllegalArgumentException("Backedge distance must be positive.");
+		}
+		return backedgeDistance * minII - backedgeDelay;
+	}
+
+}

src/main/java/graphgen/generator/components/properties/minII/feasible/FeasibleCycleInspector.java

+/*
+ * Copyright 2018 Sebastian Vollbrecht, Julian Oppermann
+ * Embedded Systems and Applications Group, TU Darmstadt
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package graphgen.generator.components.properties.minII.feasible;
+
+import graphgen.generator.components.properties.minII.MinIICycleInspector;
+import graphgen.graph.LayerStructure;
+import graphgen.graph.ResourceNode;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+
+/**
+ * This class contains some utility methods related to inspecting a given set of nodes regarding possible feasible
+ * cycles.
+ *
+ * @author Sebastian Vollbrecht
+ */
+public class FeasibleCycleInspector extends MinIICycleInspector {
+
+	public FeasibleCycleInspector(LayerStructure layers, Set<ResourceNode> nodes) {
+		super(layers, nodes);
+	}
+
+	@Override
+	public int getMinInnerDelay(int minII, int backedgeDelay, int backedgeDistance) {
+		return minInnerDelay(minII, backedgeDelay, backedgeDistance);
+	}
+
+	@Override
+	public int getMaxInnerDelay(int minII, int backedgeDelay, int backedgeDistance) {
+		return maxInnerDelay(minII, backedgeDelay, backedgeDistance);
+	}
+
+	/**
+	 * Computes all destination nodes that could potentially be the destination node for the backedges of a feasible
+	 * cycle.<p>A node can only be considered destination node if at least one other node exists which can be appended
+	 * to the destination node without exceeding the specified inner delay.<p>In case of a two-element cycle consisting
+	 * of these two nodes only, it is furthermore important to filter out nodes which might result in an
+	 * <i>infeasible</i> cycle if connected to the destination node. For example, if both nodes shared the same
+	 * resource with delay 0 and a limit of 1, an edge with delay 0 would render their induced cycle infeasible.
+	 *
+	 * @param innerDelay the feasible cycle's inner delay
+	 * @return a set containing all potential destination node candidates
+	 */
+	public Set<ResourceNode> getPossibleDstNodes(int innerDelay) {
+
+		Set<ResourceNode> possibleDstNodes = new HashSet<>();
+
+		Map<Integer, Set<ResourceNode>> nodesByDelay = new HashMap<>();
+		for (ResourceNode node : nodes) {
+			nodesByDelay.putIfAbsent(node.getDelay(), new HashSet<>());
+			nodesByDelay.get(node.getDelay()).add(node);
+		}
+
+		for (Entry<Integer, Set<ResourceNode>> firstEntry : nodesByDelay.entrySet()) {
+
+			int firstNodeDelay = firstEntry.getKey();
+
+			if (firstNodeDelay > innerDelay) {
+				continue;
+			}
+
+			for (ResourceNode dstNode : firstEntry.getValue()) {
+
+				if (possibleDstNodes.contains(dstNode)) {
+					continue;
+				}
+
+				for (Entry<Integer, Set<ResourceNode>> secondEntry : nodesByDelay.entrySet()) {
+
+					int secondNodeDelay = secondEntry.getKey();
+
+					/*
+					 * RecMinII check.
+					 */
+					if (firstNodeDelay + secondNodeDelay > innerDelay) {
+						continue;
+					}
+
+					for (ResourceNode otherNode : secondEntry.getValue()) {
+
+						if (dstNode == otherNode) {
+							continue;
+						}
+
+						/*
+						 * Infeasibility check.
+						 */
+						if (dstNode.resource == otherNode.resource) {
+							if (dstNode.resource.delay == 0 && dstNode.resource.limit == 1) {
+
+								/*
+								 * If there is no inner delay remaining if these two nodes were used,
+								 * they would need to be connected with an edge with delay 0, thus
+								 * rendering the cycle infeasible.
+								 */
+								if (innerDelay - (2 * dstNode.resource.delay) == 0) {
+									continue;
+								}
+							}
+						}
+
+						/*
+						 * If the first node can be the destination node, the second one can automatically
+						 * be the destination node as well (skipping them in the next iteration speeds up
+						 * the calculation).
+						 */
+						possibleDstNodes.add(dstNode);
+						possibleDstNodes.add(otherNode);
+						break;
+
+					}
+				}
+			}
+		}
+
+		return possibleDstNodes;
+
+	}
+
+}

src/main/java/graphgen/generator/components/properties/minII/feasible/FeasibleMinIIProperty.java

@@ -21,6 +21,7 @@ import graphgen.datastructures.Pair;
 import graphgen.enums.ModuloSchedulingFormulation;
 import graphgen.generator.GraphGenerator;
 import graphgen.generator.components.properties.Property;
+import graphgen.generator.components.properties.minII.MinIICycleInspector;
 import graphgen.generator.components.properties.util.PlannedEdge;
 import graphgen.generator.components.properties.util.SCC;
 import graphgen.generator.exceptions.MinIIImpossibleException;
@@ -108,7 +109,7 @@ public class FeasibleMinIIProperty extends Property {
 		this.backedgeDistance = backedgeDistance;
 
 		// TODO: allow inner delays >= minInnerDelay and <= maxInnerDelay
-		this.maxInnerDelay = SchedulingUtils.getMaxInnerDelay(minII, backedgeDelay, backedgeDistance);
+		this.maxInnerDelay = MinIICycleInspector.maxInnerDelay(minII, backedgeDelay, backedgeDistance);
 		this.enclosedNodes = new HashSet<>();
 
 		this.formulation = formulation;

src/main/java/graphgen/generator/components/properties/minII/infeasible/InfeasibleCycleInspector.java

@@ -17,6 +17,7 @@
 
 package graphgen.generator.components.properties.minII.infeasible;
 
+import graphgen.generator.components.properties.minII.MinIICycleInspector;
 import graphgen.graph.LayerStructure;
 import graphgen.graph.Resource;
 import graphgen.graph.ResourceNode;
@@ -27,25 +28,34 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Map.Entry;
-import java.util.Objects;
 import java.util.Set;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
 /**
  * This class contains some utility methods related to inspecting nodes and layer structure regarding possible
- * infeasible cycles.
+ * infeasible MinII cycles.
  *
  * @author Sebastian Vollbrecht
  */
-public class InfeasibleCycleInspector {
-
-	private final LayerStructure layers;
-	private final Set<ResourceNode> nodes;
+public class InfeasibleCycleInspector extends MinIICycleInspector {
 
 	public InfeasibleCycleInspector(LayerStructure layers, Set<ResourceNode> nodes) {
-		this.layers = Objects.requireNonNull(layers);
-		this.nodes = Objects.requireNonNull(nodes);
+		super(layers, nodes);
+	}
+
+	@Override
+	public int getMinInnerDelay(int minII, int backedgeDelay, int backedgeDistance) {
+		/*
+		 * We must use the absolute maximum inner delay for infeasible cycles.
+		 * Otherwise we might introduce slack, resulting in potentially feasible cycles.
+		 */
+		return maxInnerDelay(minII, backedgeDelay, backedgeDistance);
+	}
+
+	@Override
+	public int getMaxInnerDelay(int minII, int backedgeDelay, int backedgeDistance) {
+		return maxInnerDelay(minII, backedgeDelay, backedgeDistance);
 	}
 
 	/**
@@ -102,7 +112,7 @@ public class InfeasibleCycleInspector {
 	 * destination node for the backedges of an infeasible cycle. This method assumes that the infeasibility is created
 	 * by nodes using the given problematic resource.
 	 *
-	 * @param dstNodeLayer        the layer for which possible possible destination nodes are needed
+	 * @param dstNodeLayer        the layer for which possible destination nodes are needed
 	 * @param problematicResource the chosen problematic resource
 	 * @return a set containing all potential destination node candidates
 	 */

src/main/java/graphgen/generator/components/properties/minII/infeasible/InfeasibleMinIIProperty.java

@@ -159,7 +159,7 @@ public class InfeasibleMinIIProperty extends Property {
 
 		InfeasibleCycleInspector inspector = new InfeasibleCycleInspector(layers, nodes);
 
-		int maxInnerDelay = SchedulingUtils.getMaxInnerDelay(minII, backedgeDelay, backedgeDistance);
+		int maxInnerDelay = inspector.getMaxInnerDelay(minII, backedgeDelay, backedgeDistance);
 
 		/* Determine possible problematic resources from the given set of nodes. */
 		Set<Resource> problematicResources = inspector.getProblematicResources(maxInnerDelay);

src/main/java/graphgen/util/SchedulingUtils.java

@@ -405,59 +405,6 @@ public class SchedulingUtils {
 		nodeTimes.put(node, nodeSlot);
 	}
 
-
-	/**
-	 * Returns the minimum inner delay which a cycle containing backedges with the specified parameters can have without
-	 * falling below the given MinII.
-	 * <p>
-	 * It is the lower bound of the RecMinII formula's ceiling function and can be retrieved like so:
-	 * <pre>RecMinII = ceil((minInnerDelay + backedgeDelay) / backedgeDistance)</pre>
-	 * It follows that
-	 * <pre>(minInnerDelay + backedgeDelay) / backedgeDistance > RecMinII - 1</pre>
-	 * and
-	 * <pre>minInnerDelay > backedgeDistance * (RecMinII - 1) - backedgeDelay</pre><p>
-	 * Because the inner delay is an integer value, the smallest possible value which still fulfills the inequality is
-	 * the result of adding 1 to the right-hand side.
-	 *
-	 * @throws IllegalArgumentException if the MinII is not positive, if the delay is negative or if the distance is not
-	 *                                  positive
-	 */
-	public static int getMinInnerDelay(int minII, int backedgeDelay, int backedgeDistance) {
-		if (minII <= 0) {
-			throw new IllegalArgumentException("MinII must be positive.");
-		} else if (backedgeDelay < 0) {
-			throw new IllegalArgumentException("Backedge delay cannot be negative.");
-		} else if (backedgeDistance <= 0) {
-			throw new IllegalArgumentException("Backedge distance must be positive.");
-		}
-		return Math.max(0, backedgeDistance * (minII - 1) - backedgeDelay + 1);
-	}
-
-	/**
-	 * Returns the maximum inner delay which a cycle containing backedges with the specified parameters can have without
-	 * exceeding the given MinII.
-	 * <p>
-	 * It can be derived from the RecMinII formula:
-	 * <pre>RecMinII = ceil((maxInnerDelay + backedgeDelay) / backedgeDistance)</pre>
-	 * It follows that
-	 * <pre>RecMinII * backedgeDistance = maxInnerDelay + backedgeDelay</pre>
-	 * and
-	 * <pre>RecMinII * backedgeDistance - backedgeDelay = maxInnerDelay</pre>
-	 *
-	 * @throws IllegalArgumentException if the MinII is not positive, if the delay is negative or if the distance is not
-	 *                                  positive
-	 */
-	public static int getMaxInnerDelay(int minII, int backedgeDelay, int backedgeDistance) {
-		if (minII <= 0) {
-			throw new IllegalArgumentException("MinII must be positive.");
-		} else if (backedgeDelay < 0) {
-			throw new IllegalArgumentException("Backedge delay cannot be negative.");
-		} else if (backedgeDistance <= 0) {
-			throw new IllegalArgumentException("Backedge distance must be positive.");
-		}
-		return backedgeDistance * minII - backedgeDelay;
-	}
-
 	/**
 	 * Transforms the provided graph into the given formulation.
 	 *

src/test/java/graphgen/generator/components/properties/minII/MinIICycleInspectorTest.java

+/*
+ * Copyright 2018 Sebastian Vollbrecht, Julian Oppermann
+ * Embedded Systems and Applications Group, TU Darmstadt
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package graphgen.generator.components.properties.minII;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class MinIICycleInspectorTest {
+
+
+	@Test
+	public void testInnerDelays() {
+		int minII = 5;
+		int backedgeDelay = 1;
+		int backedgeDistance = 1;
+		int minInnerDelay = MinIICycleInspector.minInnerDelay(minII, backedgeDelay, backedgeDistance);
+		int maxInnerDelay = MinIICycleInspector.maxInnerDelay(minII, backedgeDelay, backedgeDistance);
+
+		assertEquals(4, minInnerDelay);
+		assertEquals(4, maxInnerDelay);
+
+		backedgeDistance = 2;
+		minInnerDelay = MinIICycleInspector.minInnerDelay(minII, backedgeDelay, backedgeDistance);
+		maxInnerDelay = MinIICycleInspector.maxInnerDelay(minII, backedgeDelay, backedgeDistance);
+
+		assertEquals(8, minInnerDelay);
+		assertEquals(9, maxInnerDelay);
+
+		minII = 50;
+		backedgeDelay = 10;
+		backedgeDistance = 5;
+		minInnerDelay = MinIICycleInspector.minInnerDelay(minII, backedgeDelay, backedgeDistance);
+		maxInnerDelay = MinIICycleInspector.maxInnerDelay(minII, backedgeDelay, backedgeDistance);
+
+		assertEquals(236, minInnerDelay);
+		assertEquals(240, maxInnerDelay);
+
+		minII = 2;
+		backedgeDelay = 4;
+		backedgeDistance = 2;
+		minInnerDelay = MinIICycleInspector.minInnerDelay(minII, backedgeDelay, backedgeDistance);
+		maxInnerDelay = MinIICycleInspector.maxInnerDelay(minII, backedgeDelay, backedgeDistance);
+
+		// Verify that the minimum delay is not negative.
+		assertEquals(0, minInnerDelay);
+		assertEquals(0, maxInnerDelay);
+	}
+}
\ No newline at end of file

src/test/java/graphgen/generator/components/properties/minII/feasible/FeasibleCycleInspectorTest.java

+/*
+ * Copyright 2018 Sebastian Vollbrecht, Julian Oppermann
+ * Embedded Systems and Applications Group, TU Darmstadt
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package graphgen.generator.components.properties.minII.feasible;
+
+import graphgen.graph.LayerStructure;
+import graphgen.graph.Resource;
+import graphgen.graph.ResourceNode;
+import graphgen.util.JavaUtils;
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class FeasibleCycleInspectorTest {
+
+	@Test
+	public void getPossibleInnerDelays() {
+
+		Resource problematic = new Resource("limited", 1, 2);
+		Resource unlimited = new Resource("unlimited", 0);
+
+		Map<Integer, Integer> depthsByID = new HashMap<>();
+
+		depthsByID.put(2, 0);
+		depthsByID.put(3, 1);
+		depthsByID.put(4, 2);
+		depthsByID.put(5, 2);
+		depthsByID.put(6, 3);
+		depthsByID.put(7, 3);
+		depthsByID.put(8, 4);
+		depthsByID.put(9, 5);
+		LayerStructure layers = new LayerStructure(depthsByID);
+
+		ResourceNode node2 = new ResourceNode(2, unlimited);
+		ResourceNode node3 = new ResourceNode(3, unlimited);
+		ResourceNode node4 = new ResourceNode(4, problematic);
+		ResourceNode node5 = new ResourceNode(5, unlimited);
+		ResourceNode node6 = new ResourceNode(6, problematic);
+		ResourceNode node7 = new ResourceNode(7, unlimited);
+		ResourceNode node8 = new ResourceNode(8, problematic);
+		ResourceNode node9 = new ResourceNode(9, problematic);
+		Set<ResourceNode> nodes = JavaUtils.asSet(node2, node3, node4, node5, node6, node7, node8, node9);
+
+		FeasibleCycleInspector inspector = new FeasibleCycleInspector(layers, nodes);
+
+		assertEquals(0, inspector.getMinInnerDelay(5, 5, 1));
+		assertEquals(1, inspector.getMinInnerDelay(5, 4, 1));
+		assertEquals(2, inspector.getMinInnerDelay(5, 3, 1));
+		assertEquals(3, inspector.getMinInnerDelay(5, 2, 1));
+		assertEquals(4, inspector.getMinInnerDelay(5, 1, 1));
+		assertEquals(5, inspector.getMinInnerDelay(5, 0, 1));
+
+		assertEquals(0, inspector.getMaxInnerDelay(5, 5, 1));
+		assertEquals(1, inspector.getMaxInnerDelay(5, 4, 1));
+		assertEquals(2, inspector.getMaxInnerDelay(5, 3, 1));
+		assertEquals(3, inspector.getMaxInnerDelay(5, 2, 1));
+		assertEquals(4, inspector.getMaxInnerDelay(5, 1, 1));
+		assertEquals(5, inspector.getMaxInnerDelay(5, 0, 1));
+
+		assertEquals(14, inspector.getMinInnerDelay(10, 5, 2));
+		assertEquals(15, inspector.getMinInnerDelay(10, 4, 2));
+		assertEquals(16, inspector.getMinInnerDelay(10, 3, 2));
+
+		assertEquals(15, inspector.getMaxInnerDelay(10, 5, 2));
+		assertEquals(16, inspector.getMaxInnerDelay(10, 4, 2));
+		assertEquals(17, inspector.getMaxInnerDelay(10, 3, 2));
+
+		assertEquals(11, inspector.getMinInnerDelay(5, 2, 3));
+		assertEquals(12, inspector.getMinInnerDelay(5, 1, 3));
+		assertEquals(13, inspector.getMinInnerDelay(5, 0, 3));
+
+		assertEquals(13, inspector.getMaxInnerDelay(5, 2, 3));
+		assertEquals(14, inspector.getMaxInnerDelay(5, 1, 3));
+		assertEquals(15, inspector.getMaxInnerDelay(5, 0, 3));
+
+	}
+
+	@Test
+	public void getPossibleDstNodes_ZeroDelay() {
+
+		Resource limited = new Resource("limited", 0, 1);
+
+		Map<Integer, Integer> depthsByID = new HashMap<>();
+
+		depthsByID.put(2, 0);
+		depthsByID.put(3, 1);
+		depthsByID.put(4, 2);
+		depthsByID.put(5, 2);
+		depthsByID.put(6, 3);
+		depthsByID.put(7, 3);
+		depthsByID.put(8, 4);
+		depthsByID.put(9, 5);
+		LayerStructure layers = new LayerStructure(depthsByID);
+
+		ResourceNode node2 = new ResourceNode(2, limited);
+		ResourceNode node3 = new ResourceNode(3, limited);
+		ResourceNode node4 = new ResourceNode(4, limited);
+		ResourceNode node5 = new ResourceNode(5, limited);
+		ResourceNode node6 = new ResourceNode(6, limited);
+		ResourceNode node7 = new ResourceNode(7, limited);
+		ResourceNode node8 = new ResourceNode(8, limited);
+		ResourceNode node9 = new ResourceNode(9, limited);
+		Set<ResourceNode> nodes = JavaUtils.asSet(node2, node3, node4, node5, node6, node7, node8, node9);
+
+		FeasibleCycleInspector inspector = new FeasibleCycleInspector(layers, nodes);
+
+		// We cannot create a feasible cycle with an inner delay of 0 without introducing an infeasibility.
+		assertTrue(inspector.getPossibleDstNodes(0).isEmpty());
+		assertEquals(nodes, inspector.getPossibleDstNodes(1));
+		assertEquals(nodes, inspector.getPossibleDstNodes(2));
+		// ...
+
+	}
+
+	@Test
+	public void getPossibleDstNodes_ZeroDelay2() {
+
+		Resource limited = new Resource("limited", 0, 1);
+		Resource other = new Resource("other", 0, 1);
+
+		Map<Integer, Integer> depthsByID = new HashMap<>();
+
+		depthsByID.put(2, 0);
+		depthsByID.put(3, 1);
+		depthsByID.put(4, 2);
+		depthsByID.put(5, 2);
+		depthsByID.put(6, 3);
+		depthsByID.put(7, 3);
+		depthsByID.put(8, 4);
+		depthsByID.put(9, 5);
+		LayerStructure layers = new LayerStructure(depthsByID);
+
+		ResourceNode node2 = new ResourceNode(2, other);
+		ResourceNode node3 = new ResourceNode(3, limited);
+		ResourceNode node4 = new ResourceNode(4, limited);
+		ResourceNode node5 = new ResourceNode(5, limited);
+		ResourceNode node6 = new ResourceNode(6, limited);
+		ResourceNode node7 = new ResourceNode(7, limited);
+		ResourceNode node8 = new ResourceNode(8, limited);
+		ResourceNode node9 = new ResourceNode(9, limited);
+		Set<ResourceNode> nodes = JavaUtils.asSet(node2, node3, node4, node5, node6, node7, node8, node9);
+
+		FeasibleCycleInspector inspector = new FeasibleCycleInspector(layers, nodes);
+
+		// Since we have at least one node with a non-problematic resource, we can easily create a feasible cycle.
+		assertEquals(nodes, inspector.getPossibleDstNodes(0));
+		assertEquals(nodes, inspector.getPossibleDstNodes(1));
+		// ...
+
+	}
+
+	@Test
+	public void getPossibleDstNodes_NonZeroDelay() {
+
+		Resource limited = new Resource("limited", 3, 1);
+		Resource other = new Resource("other", 5, 1);
+
+		Map<Integer, Integer> depthsByID = new HashMap<>();
+
+		depthsByID.put(2, 0);
+		depthsByID.put(3, 1);
+		depthsByID.put(4, 2);
+		depthsByID.put(5, 2);
+		depthsByID.put(6, 3);
+		depthsByID.put(7, 3);
+		depthsByID.put(8, 4);
+		depthsByID.put(9, 5);
+		LayerStructure layers = new LayerStructure(depthsByID);
+
+		ResourceNode node2 = new ResourceNode(2, other);
+		ResourceNode node3 = new ResourceNode(3, other);
+		ResourceNode node4 = new ResourceNode(4, other);
+		ResourceNode node5 = new ResourceNode(5, other);
+		ResourceNode node6 = new ResourceNode(6