“…In the future, we will try to compare our work with other works on the inference of tree languages and of context-free languages, as they are contained, e.g., in [5,27,30,33,43,47,48,61,[64][65][66][71][72][73]. Moreover, it would be interesting to extend the work to other, more general classes of tree languages and the corresponding languages of yielded strings, see [70] for a short exposition.…”