bool accept(automaton *am, int dep, char *word, state_t act_st) {
  if (dep == strlen(word)) {
    return am->acc[act_st]; // true if accepting
  }
  bool res;
  int idx = alph_idx(word[dep]);
  if (is_existential(am, act_st)) {
    res = false;
    int i = 0;
    while (!res && am->T[act_st][idx][i] != (char) -1) {
      if (accept(am, dep + 1, word, (state_t) am->T[act_st][idx][i]))
        res = true;
      i++;
    }
  }
  else { // universal
    res = true;
    int i = 0;
    while (res && am->T[act_st][idx][i] != (char) -1) {
      if (accept(am, dep + 1, word, (state_t) am->T[act_st][idx][i]))
        res = false;
      i++;
    }
  }
  return res;
}