This artical mainly presents the elementary thought and method that David. Gries, professor of the Cornell University applied in his research on programming with WP (weakest precondition) in small program aspect.

• 本文主要简介美国康奈尔(Coroell)大学大卫·格里斯(David.；Gries)教授在小程序方面；运用wp(weakest precondition)研究程序设计的基本思想和方法。