One can only estimate some bounds of f(r) except for f(3)=3 and f(4)=4. In this paper, the applications of minimal unsatisfiable formulas are described for transformations between CNF formulas.

• 函数f是否可计算是一个开问题；除了知道f(3)=3；f(4)=4外；只能估计f(r)的界.；描述了极小不可满足公式在CNF公式类之间转换中的作用