diff --git a/src/graphtea/extensions/algorithms/shortestpath/algs/Dijkstra.java b/src/graphtea/extensions/algorithms/shortestpath/algs/Dijkstra.java
index 73fa89a2..13a00ee7 100755
--- a/src/graphtea/extensions/algorithms/shortestpath/algs/Dijkstra.java
+++ b/src/graphtea/extensions/algorithms/shortestpath/algs/Dijkstra.java
@@ -97,7 +97,7 @@ public int compare(Vertex o1, Vertex o2) {
                         target.setMark(true);
                         target.setColor(5);
                         Q.add(target);
-                        prev.set(edge.source.getId(), edge.target);
+                        prev.set(target.getId(), vMin);
                     }
                 }
             }
diff --git a/src/graphtea/extensions/generators/BananaTreeGenerator.java b/src/graphtea/extensions/generators/BananaTreeGenerator.java
index 2bb599a1..e6b44d23 100755
--- a/src/graphtea/extensions/generators/BananaTreeGenerator.java
+++ b/src/graphtea/extensions/generators/BananaTreeGenerator.java
@@ -76,7 +76,7 @@ private static GraphModel generateBananaTree(int n, int k) {
 
             GPoint[] sR = PositionGenerators.circle(1000, center.x, center.y, k);
             for (int j = 0; j < k; j++) {
-                if(j == (i + k/2)%n) continue;
+                if (j == (i * k / n + k / 2) % k) continue;
                 curv = new Vertex();
                 g.insertVertex(curv);
                 setloc(curv, sR[j]);
diff --git a/src/graphtea/plugins/main/select/MakeSelectionComplementGraph.java b/src/graphtea/plugins/main/select/MakeSelectionComplementGraph.java
index 69139970..ef1af84b 100755
--- a/src/graphtea/plugins/main/select/MakeSelectionComplementGraph.java
+++ b/src/graphtea/plugins/main/select/MakeSelectionComplementGraph.java
@@ -41,14 +41,20 @@ public void action(GraphData gd) {
 
     protected void doEdgeOperation(GraphModel g, HashSet<Vertex> v) {
         boolean directed = g.isDirected();
-        
+
         for (Vertex v1 : v) {
             for (Vertex v2 : v) {
-                if (!directed)
-                    if (v1.getId() < v2.getId())
-                        continue;
+                if (v1 == v2) {
+                    continue;
+                }
+                if (!directed && v1.getId() < v2.getId()) {
+                    continue;
+                }
                 if (g.isEdge(v1, v2)) {
                     g.removeAllEdges(v1, v2);
+                    if (!directed) {
+                        g.removeAllEdges(v2, v1);
+                    }
                 } else {
                     g.insertEdge(new Edge(v1, v2));
                 }
diff --git a/test/AlgorithmsTest.java b/test/AlgorithmsTest.java
index 8c4e206e..d03d83ae 100644
--- a/test/AlgorithmsTest.java
+++ b/test/AlgorithmsTest.java
@@ -25,7 +25,7 @@ public class AlgorithmsTest {
     // -------------------------------------------------------------------------
 
     /** Build a simple directed weighted path 0→1(w=1)→2(w=2)→3(w=3) and verify
-     *  that Dijkstra from vertex 0 encodes the correct successor chain. */
+     *  that Dijkstra from vertex 0 encodes the correct predecessor chain. */
     @Test
     public void testDijkstraLinearPath() throws Exception {
         GraphModel g = new GraphModel(true);
@@ -40,10 +40,11 @@ public void testDijkstraLinearPath() throws Exception {
         List<Vertex> prev = new Dijkstra().getShortestPath(g, v0);
 
         assertNotNull(prev);
-        // prev[i] is the successor of vertex i on the shortest path from v0
-        assertEquals(v1, prev.get(v0.getId()));
-        assertEquals(v2, prev.get(v1.getId()));
-        assertEquals(v3, prev.get(v2.getId()));
+        // prev[i] is the predecessor of vertex i on the shortest path from v0
+        assertNull(prev.get(v0.getId()), "Source vertex has no predecessor");
+        assertEquals(v0, prev.get(v1.getId()), "Predecessor of v1 is v0");
+        assertEquals(v1, prev.get(v2.getId()), "Predecessor of v2 is v1");
+        assertEquals(v2, prev.get(v3.getId()), "Predecessor of v3 is v2");
     }
 
     /** Dijkstra on a complete K4 graph should return a prev-array of size 4
@@ -71,9 +72,12 @@ public void testDijkstraDiamond() throws Exception {
 
         List<Vertex> prev = new Dijkstra().getShortestPath(g, v0);
         assertNotNull(prev);
-        // The path to v1 should go via v2, not directly
-        assertEquals(v2, prev.get(v0.getId()),
-                "Dijkstra should prefer short path 0→2 over long path 0→1");
+        // prev[i] is the predecessor of vertex i on the shortest path from v0
+        assertNull(prev.get(v0.getId()), "Source vertex has no predecessor");
+        assertEquals(v0, prev.get(v2.getId()),
+                "Predecessor of v2 is v0 (direct path 0→2)");
+        assertEquals(v2, prev.get(v1.getId()),
+                "Predecessor of v1 is v2 (shortest path 0→2→1)");
     }
 
     // -------------------------------------------------------------------------