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;
  }
}