public static Stella_Object symbolDbuildProposition(Symbol symbol) {
    { Proposition proposition = null;

      if (symbol == Logic.SYM_STELLA_TRUE) {
        proposition = Logic.TRUE_PROPOSITION;
      }
      else if (symbol == Logic.SYM_STELLA_FALSE) {
        proposition = Logic.FALSE_PROPOSITION;
      }
      else {
        return (Logic.evaluateSymbolTerm(symbol));
      }
      return (proposition);
    }
  }