1 files changed, 2 insertions, 2 deletions

diff --git a/Solvers/VIATRA-Solver/hu.bme.mit.inf.dslreasoner.viatrasolver.logic2viatra/src/hu/bme/mit/inf/dslreasoner/viatrasolver/logic2viatra/interval/IntervalAggregationOperator.xtend b/Solvers/VIATRA-Solver/hu.bme.mit.inf.dslreasoner.viatrasolver.logic2viatra/src/hu/bme/mit/inf/dslreasoner/viatrasolver/logic2viatra/interval/IntervalAggregationOperator.xtend
index 940c71bb..21d3d73b 100644
--- a/Solvers/VIATRA-Solver/hu.bme.mit.inf.dslreasoner.viatrasolver.logic2viatra/src/hu/bme/mit/inf/dslreasoner/viatrasolver/logic2viatra/interval/IntervalAggregationOperator.xtend
+++ b/Solvers/VIATRA-Solver/hu.bme.mit.inf.dslreasoner.viatrasolver.logic2viatra/src/hu/bme/mit/inf/dslreasoner/viatrasolver/logic2viatra/interval/IntervalAggregationOperator.xtend
@@ -36,13 +36,13 @@ class IntervalAggregationOperator implements IMultisetAggregationOperator<Interv
 
         override getAggregate(IntervalRedBlackNode result) {
                 if (result.leaf) {
-                        null
+                        mode.neutral
                 } else {
                         result.result
                 }
         }
 
         override aggregateStream(Stream<Interval> stream) {
-                stream.reduce(mode).orElse(null)
+                stream.reduce(mode).orElse(mode.neutral)
         }
 }