From p.singleton@keele.ac.uk  Wed Sep 20 14:04:32 2000
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Date: Wed, 20 Sep 2000 12:34:31 +0100
From: Paul Singleton <p.singleton@keele.ac.uk>
Organization: SmartArts Computing Consultancy
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To: "Richard A. O'Keefe" <ok@atlas.otago.ac.nz>
CC: prolog@swi.psy.uva.nl
Subject: Re: Circular references
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"Richard A. O'Keefe" wrote:

> ... (what _should_ sort/2 do, given an infinite list? fail I guess)

As soon as the cycle is detected:

 * a duplicate-deleting sort/2 could yield an ordset of elements seen
   so far

 * a duplicate-preserving sort/2 could give L where L = [MinElement|L] ;-/

Paul Singleton


