逐步描述、变换及证明的软件开发过程包含两个转换,一是从非形式的用户需求到形式描述,一是从形式描述到算法实现。开发过程中的关键是如何做出设计决定。为了更好地维护、重用软件以及程序证明,不仅仅要对软件的形式描述及实现做文档记录,也要记下开发过程中所做的每一步决定。我 们用两个例子来说明如上这种逐步求精的方法以及设计决定在其中所起的作用,并且我们实现了一个包括SPEC、OOMM、PROT、VERI几个子系统组成的环境来支持上述过程。

The program development preocess of stepwise specification, transformation and verification consists of two transitions. One is from the informal requirement to the formal specificaiton, the other is from the formal specification to the algorithmic implementation. The key point in the development process is how to make design decisions. In order to maintain and adapt software and to verify, not only should the specification and the implementation be recorded, but also the design decisions made during the development.We give two examples to demonstrate this methodo;ogy and how the design decisions take role in it.An environment which includes several subsystems called SPEC,PROT,VERI,and OOMM is implemented to support the above process.