Re: findall with @< fails on when there is only one answer

Roelof Wobben <[email protected]> Fri, 28 Mar 2014 21:40:46 +0000

Newsgroups	gmane.comp.ai.prolog.swi
Message-ID	<[email protected]>

Found the answer  in this discussion: https://groups.google.com/forum/#!topic/comp.lang.prolog/shp_5cTfOOo

Roelof

From: [email protected]
To: [email protected]
Subject: findall with @< fails on when there is only one answer
Date: Fri, 28 Mar 2014 19:47:44 +0000

Hello, 

I use this in a predicate :

  findall(Person - Y, (siblings(Person,Y), Person @< Y)  Sibs).

This one gives a empty list if the person is futher on the alfabeth then Y.

If I delete it , it gives the right answers.
Also if there is more then 1 answers , it gives the right answer.

Is it right that sorting (@<) is not working when there is only 1 answer.
and if so, can I then better sort when there are more then 1 answer. 

Roelof

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