Re: terminology: double-rooted DAG?

Vladimir Alexiev <vladimir@cs.ualberta.ca>
7 Mar 1998 22:41:17 -0500

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Related articles
terminology: double-rooted DAG? markh@usai.asiainfo.com (Mark Harrison) (1998-03-03)
Re: terminology: double-rooted DAG? mfinney@inmind.com (1998-03-06)
Re: terminology: double-rooted DAG? dwight@pentasoft.com (1998-03-06)
Re: terminology: double-rooted DAG? vladimir@cs.ualberta.ca (Vladimir Alexiev) (1998-03-07)
Re: terminology: double-rooted DAG? markh@usai.asiainfo.com (Mark Harrison) (1998-03-07)
Re: terminology: double-rooted DAG? mfinney@inmind.com (1998-03-08)
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From: Vladimir Alexiev <vladimir@cs.ualberta.ca>
Newsgroups: comp.compilers
Date: 7 Mar 1998 22:41:17 -0500
Organization: University of Alberta, Computing Science
References: 98-03-021 98-03-042
Keywords: theory
In-reply-to: mfinney@inmind.com's message of 6 Mar 1998 16:48:42 -0500

mfinney@inmind.com writes:


> :>1. It always has a defined root node (like a tree), and
> :>2. There is also a "tail" node
> Its called a "lattice". One of the definitions of a lattice is that it
> is a dag which contains both a least upper bound and greatest lower
> bound -- precisely what you have described.


No, because he never stated that his DAG is to be interpreted as a
partial order. In other words, a DAG is not necessarily transitive,
and we don't know if transitive edges are assumed, either.


The correct answer is: who cares :-) Now, if he had asked about some
algorithms that might be applicable to some problem on such a
structure, it would matter...
--


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