在 Prolog 中断言数字谓词 [英] Assert numeric predicates in Prolog

问题描述

Prolog 中是否有可能断言代表数字的事实?例如，我想使用谓词 distance/2 并断言像 distance(town1, city2) = 1200 这样的事实.

Is there a possibility in Prolog to assert facts that represent a number? For example, I would like to use a predicate distance/2 and assert facts like distance(town1, city2) = 1200.

推荐答案

distance(town1, city2) = 1200 术语是术语 '='(distance(town1) 的语法糖, city2), 1200) as (=)/2 是一个标准的 Prolog 中缀运算符.(=)/2 也是标准的统一内置谓词.在大多数 Prolog 系统中，用户不能重新定义内置谓词.因此，您不能为它们断言子句，因为这相当于重新定义谓词.Carlo 建议使用 distance/3 谓词可能是最好的解决方案.

The distance(town1, city2) = 1200 term is syntactic sugar for the term '='(distance(town1, city2), 1200) as (=)/2 is a standard Prolog infix operator. (=)/2 is also the standard unification built-in predicate. In most Prolog systems, built-in predicates cannot be redefined by the user. Thus, you cannot assert clauses for them as that would amount to redefine the predicate. Carlo's suggestion of using a distance/3 predicate is likely the best solution.

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