Question

我有一套规则;

family(Mother,Father,Children).

儿童是一个清单（例如[ag, bg]）。

parent(X,Y) :-
    family(X,_,_) -> mother(X,Y); father(X,Y).

根据上面的条款，如果我放入父母，它会正确地给我孩子。但是，如果我把孩子放进去，我就无法得到父母。

我也尝试为Child制定一个条款;

child(X,Y) :-
    mother(A,X),
    father(B,X),
    Y=A,B.

母亲和父亲的工作正常，但我需要两个变量才能转到Y。

有什么建议吗？

Answer 1

您可以简化子谓词：

>>> from shortener.models import KirrURL
>>> from django.shortcuts import get_object_or_404
>>> obj = get_object_or_404(KirrURL,shortcode='pric3e')

Traceback (most recent call last):File"/Users/phil/Desktop/django110/lib/python3.5/site
packages/django/shortcuts.py", line 85, in get_object_or_404
return queryset.get(*args, **kwargs)
File "/Users/phil/Desktop/django110/lib/python3.5/site-packages/django/db/models/query.py", line 385, in get
self.model._meta.object_name
shortener.models.DoesNotExist: KirrURL matching query does not exist.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/Users/phil/Desktop/django110/lib/python3.5/site-packages/django/shortcuts.py", line 93, in get_object_or_404
raise Http404('No %s matches the given query.' % queryset.model._meta.object_name)
django.http.response.Http404: No KirrURL matches the given query.

>>> obj = KirrURL.objects.get(shortcode='pric3e')
>>> obj
<KirrURL: http://google.com>
>>> obj.id
1
>>> obj.url
'http://google.com'

Prolog - 问题条款双向进行

1 个答案: