【摘要】 本文介绍了Ｐｒｏ树的生成规则，并以一个递归程序为例，对追踪过程和由Ｐｒｏ树图解的运行机制进行了详细比较，说明Ｐｒｏ树可作为一种直现、形象、易于理解的辅助工具，用于Ｐｒｏｌｏｇ程序的设计和调试。更多还原

【Abstract】 This paper presents the symbols and the generating rules of the Pro-tree. It compares a program tracing with graphic procedure of the Pro-tree in detail. From this, we can see that the Pro-tree can be an imaginable, audio-visual, easy-to-understand auxiliary debugging tool.更多还原