 					END IF;
 				END IF;
 			WHEN '&'::calendar_operator THEN -- Must calculate intersection
-				RAISE WARNING 'Intersection';
 				IF _start_date IS NULL THEN
 					-- We assume that if _start_date is NULL _end_date is also NULL
 					_computed_date_pair.start_date := NULL;

					END IF;
				END IF;
		END CASE;
		RAISE WARNING 'Result (%,%)',_computed_date_pair.start_date,_computed_date_pair.end_date;
		RETURN _computed_date_pair;
	END;
	$$;

	DECLARE
		_computed_date_pair date_pair;
	BEGIN
		-- RAISE DEBUG 'Operate this : (%,%) % (%,%)',previous_bounds.start_date,previous_bounds.end_date,_operator,_start_date,_end_date;		
		CASE _operator
			WHEN '+'::calendar_operator THEN -- Date muse be added
				IF _start_date IS NULL THEN
					-- We assume that if _start_date is NULL _end_date is also NULL
					_computed_date_pair := previous_bounds;
