如何写好谓词（not Between）

发布于 2024-11-01 10:38:54 字数 300 浏览 1 评论 0原文

我编写代码如下

testb :-
    X::1..10,
    V1 = 3,
    V2 = 6,
    testbb(X,V1,V2),
    writeln(X).

testbb(X,V1,V2) :-
    (
      count(I,V1,V2),param(X,V1,V2) do 
      X#\=I 
    ).


?- testb.
Yes (0.00s cpu)
_385{[1, 2, 7 .. 10]}

它运行良好，但我认为它效率不高，

非常感谢:)

原文

I write code follwing

testb :-
    X::1..10,
    V1 = 3,
    V2 = 6,
    testbb(X,V1,V2),
    writeln(X).

testbb(X,V1,V2) :-
    (
      count(I,V1,V2),param(X,V1,V2) do 
      X#\=I 
    ).


?- testb.
Yes (0.00s cpu)
_385{[1, 2, 7 .. 10]}

It works well, but i think it isn't efficient

Thanks very much :)

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-残月青衣踏尘吟 2024-11-08 10:38:54

您可以通过以下方式将 X 的域限制在 V1 到 V2 的范围之外：

not_between(X, Lower, Upper) :-
     % it is not the case that X is both greater and 
     % equal to Lower, and less than or equal to Upper: 
    #\ ((X #>= Lower) #/\ (X #=< Upper)).

替换您的 testbb/3 与 not_ Between/3。此定义确保 X 无法准确地采用 Lower 和 Upper 值；如果您希望将范围约束包含在 X 的域中，则可以使用范围约束 #< 和 #>。

这已经过测试并可与 SWI-Prolog 一起使用。要在 SWI-Prolog 文件中使用 CLP(FD)，请确保在指令中导入源文件顶部的 CLP(FD) 库，如下所示：

:- use_module(library(clpfd)).

You could confine the domain of X to lie outside the range within V1 to V2 by:

not_between(X, Lower, Upper) :-
     % it is not the case that X is both greater and 
     % equal to Lower, and less than or equal to Upper: 
    #\ ((X #>= Lower) #/\ (X #=< Upper)).

Replace your testbb/3 with not_between/3. This definition ensures that X cannot take on Lower and Upper values exactly; you could use the range constraints #< and #> instead if you wish them to be included in the domain for X.

This is tested and working with SWI-Prolog. To use CLP(FD) in a SWI-Prolog file, make sure you import the CLP(FD) library at the top of your source file in a directive, like this: