1 files changed, 9 insertions, 0 deletions

diff --git a/Solvers/VIATRA-Solver/hu.bme.mit.inf.dslreasoner.viatrasolver.logic2viatra/src/hu/bme/mit/inf/dslreasoner/viatrasolver/logic2viatra/interval/IntervalAggregationMode.java b/Solvers/VIATRA-Solver/hu.bme.mit.inf.dslreasoner.viatrasolver.logic2viatra/src/hu/bme/mit/inf/dslreasoner/viatrasolver/logic2viatra/interval/IntervalAggregationMode.java
index f5bd2efc..66dcb00f 100644
--- a/Solvers/VIATRA-Solver/hu.bme.mit.inf.dslreasoner.viatrasolver.logic2viatra/src/hu/bme/mit/inf/dslreasoner/viatrasolver/logic2viatra/interval/IntervalAggregationMode.java
+++ b/Solvers/VIATRA-Solver/hu.bme.mit.inf.dslreasoner.viatrasolver.logic2viatra/src/hu/bme/mit/inf/dslreasoner/viatrasolver/logic2viatra/interval/IntervalAggregationMode.java
@@ -21,6 +21,11 @@ public enum IntervalAggregationMode implements BinaryOperator<Interval> {
                                 }
                         };
                 }
+                
+                @Override
+                public Interval getNeutral() {
+                        return Interval.ZERO;
+                }
         },
 
         JOIN("intervalJoin", "Calculate the smallest interval containing all the intervals in a set") {
@@ -63,4 +68,8 @@ public enum IntervalAggregationMode implements BinaryOperator<Interval> {
         }
 
         public abstract IntervalRedBlackNode createNode(Interval interval);
+        
+        public Interval getNeutral() {
+                return Interval.EMPTY;
+        }
 }