To solve these problems we will restrict our attention to those queries that are domain independent, i.e., the queries that return the same result for a database under all of its schemas.
要解决这些问题我们将把我们的注意力限制于“域独立”的那些查询，就是说，对一个数据库的查询在它的所有模式下都返回同样的结果。