final BulkIterationBase<?> enclosingIteration = holder.getContainingBulkIteration();
        final BulkIterationNode containingIterationNode =
              (BulkIterationNode) this.parent.con2node.get(enclosingIteration);
        
        // catch this for the recursive translation of step functions
        BulkPartialSolutionNode p = new BulkPartialSolutionNode(holder, containingIterationNode);
        p.setDegreeOfParallelism(containingIterationNode.getDegreeOfParallelism());
        p.setSubtasksPerInstance(containingIterationNode.getSubtasksPerInstance());
        n = p;
      }
      else if (c instanceof WorksetPlaceHolder) {
        final WorksetPlaceHolder<?> holder = (WorksetPlaceHolder<?>) c;
        final DeltaIterationBase<?, ?> enclosingIteration = holder.getContainingWorksetIteration();
        final WorksetIterationNode containingIterationNode =
              (WorksetIterationNode) this.parent.con2node.get(enclosingIteration);
        
        // catch this for the recursive translation of step functions
        WorksetNode p = new WorksetNode(holder, containingIterationNode);
        p.setDegreeOfParallelism(containingIterationNode.getDegreeOfParallelism());
        p.setSubtasksPerInstance(containingIterationNode.getSubtasksPerInstance());
        n = p;
      }
      else if (c instanceof SolutionSetPlaceHolder) {
        final SolutionSetPlaceHolder<?> holder = (SolutionSetPlaceHolder<?>) c;
        final DeltaIterationBase<?, ?> enclosingIteration = holder.getContainingWorksetIteration();
        final WorksetIterationNode containingIterationNode =
              (WorksetIterationNode) this.parent.con2node.get(enclosingIteration);
        
        // catch this for the recursive translation of step functions
        SolutionSetNode p = new SolutionSetNode(holder, containingIterationNode);
        p.setDegreeOfParallelism(containingIterationNode.getDegreeOfParallelism());
        p.setSubtasksPerInstance(containingIterationNode.getSubtasksPerInstance());
        n = p;
      }
      else {
        throw new IllegalArgumentException("Unknown operator type: " + c.getClass() + " " + c);
      }