abstract sclass AbstractThoughtSpace implements AI_PostHandler {

  AbstractThoughtSpace parent;

  *() {}

  *(AbstractThoughtSpace *parent) {}

  // take unshortened queries

  abstract L<TripleRef<Symbol>> get(Symbol query);

  abstract L<TripleRef<Symbol>> get(Symbol query, int position);

  abstract L<TripleWeb> getTriples(Symbol query);

  abstract L<TripleWeb> getTriples(Symbol query, int position);

  abstract L<TripleWeb> getOneTwo(Symbol a, Symbol b);

  // existence of triple has already been checked

  public abstract GlobalID postTriple(T3<Symbol> t);

  abstract int size();

  // doesn't take variables

  public bool hasTriple(Symbol a, Symbol b, Symbol c) {

    ret findTriple(a, b, c) != null;

  }

  // doesn't take variables

  public TripleWeb findTriple(Symbol a, Symbol b, Symbol c) {

    L<TripleWeb> l = shortestList3(getTriples(a, 0), getTriples(b, 1), getTriples(c, 2));

    if (l != null) for (TripleWeb w : l)

      if (w != null && tripleEqic(w, a, b, c))

        ret w;

    null;

  }

  public bool hasTriple_verified(Symbol a, Symbol b, Symbol c) {

    L<TripleWeb> l = shortestList3(getTriples(a, 0), getTriples(b, 1), getTriples(c, 2));

    if (l != null) for (TripleWeb w : l)

      if (w != null && w.verified() && tripleEqic(w, a, b, c))

        true;

    false;

  }

}