static L<PTElement> ai_parseTree_getChildren(AI_BottomUpParser1 parser, L<WeightedProduction> productions, PTElement e) {

  if (e.children == null) {

    e.children = ai_parseTree_makeChildren(parser, productions, e);

    for (PTElement child : unnull(e.children)) child.parent = e;

  }

  ret e.children;

}

static L<PTElement> ai_parseTree_makeChildren(AI_BottomUpParser1 parser, L<WeightedProduction> productions, final PTElement e) {

  if (e instanceof ChooseCategory)

    ret map(((ChooseCategory) e).categories, func(S cat) -> PTElement { new HaveCategory(((ChooseCategory) e).word, cat) });

  if (e instanceof HaveCategory) {

    final HaveCategory h = cast e;

    L<ai_Reconstructed> l = ai_buParser1_reconstructedProductions(parser, productions, h.word, h.category);

    ret map(l, func(ai_Reconstructed r) -> PTElement {

      r.production.b == null

        ? new HaveCategory(r.a, r.production.a, r)

        : new ChoosePart(h.word, r)

    });

  }

  if (e instanceof ChoosePart) {

    ai_Reconstructed r = ((ChoosePart) e).reconstruction;

    ret (L) ll(new HaveCategory(r.a, r.production.a),

      new HaveCategory(r.b, r.production.b));

  }

  null;

}