diff --git a/src/eva2/server/go/strategies/ANPSO.java b/src/eva2/server/go/strategies/ANPSO.java
index 0f1bbebb..61b93921 100644
--- a/src/eva2/server/go/strategies/ANPSO.java
+++ b/src/eva2/server/go/strategies/ANPSO.java
@@ -22,6 +22,7 @@ import eva2.tools.chart2d.DPointSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
+import java.util.Vector;
 
 /**
  * The Adaptive Niching PSO(ANPSO)[1] extends the particle swarm optimizer (PSO)