Prolog 给出错误“未定义的过程"尝试使用时:- [英] Prolog gives error "undefined procedure" when trying to use :-

问题描述

我在 Windows 上使用 SWI-Prolog 并收到以下错误:

I'm using SWI-Prolog on Windows and am getting the following error:

14 ?- parent(X, Y) :- child(Y, X).
ERROR: toplevel: Undefined procedure: (:-)/2 (DWIM could not correct)

我不完全确定发生了什么，因为这在上周起作用了，而且我刚刚开始学习 Prolog.

I'm not entirely sure what's going on, as this worked last week and I am just starting to learn Prolog.

推荐答案

FAQ 说明了一切:http://www.swi-prolog.org/FAQ/ToplevelMode.html

The FAQ says it all: http://www.swi-prolog.org/FAQ/ToplevelMode.html

您需要创建一个文件并在那里编写带有规则的程序.顶级命令行将只允许您发出查询.

You need to create a file and write your program with rules there. The top level command line will only allow you to issue queries.

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