From: Bruce Lilly (blilly@erols.com)
Date: Thu Apr 01 2004 - 20:48:18 CST
Charles Lindsey wrote:
> In <4065FA65.4050308@erols.com> Bruce Lilly <blilly@erols.com> writes:
>
>
>>Charles Lindsey wrote:
>
>
>>>Indeed so. But the whole point is that it is not necessary to construct
>>>the entire dependency graph in order to provide an acceptable presentation
>>>of articles within a newsreader.
>
>
>>It is if the definition of "acceptable" includes conformance to
>>reality rather than some arbitrary presentation.
>
>
> What is "reality"?
"[R]eality" in this case refers to the actual dependency relationship
between the postulated articles, said relationship having been the basis
of the specified References and In-Reply-To fields. And that turns out
(unsurprisingly) to be what can be regenerated if all of that information
contained in those fields is taken into account (and, also unsurprisingly,
not possible w/o that information).
> The whole point is that, if followups to multiple precursors are going to
> be recognized, then what you have is a DAG rather than a tree. In which
> case, reading agents are going to have to display that DAG in some manner.
> So what is a reasonable way to display a DAG, especially it there are lots
> of bits inside it that are purely tree-like?
That's purely up to the UA author; we don't dictate display form. We
are responsible for specifying how followups are indicated via message
header fields such as References and In-Reply-To. Whether/How UA authors
use that information for display is outside of scope.
> How, for example, would you present the example that you
> gave?
The obvious answer is "exactly as I have presented it".
> [...] the complete dependency graph (which is
> expensive to obtain)
Bald assertion, which fails on two accounts:
1. The graph can be conveyed simply in each message by providing the
edge information (the References field provides the nodes); that
is much cheaper than having to grope through each ancestor message
(e.g. to compare Subject fields).
2. Determining the dependency graph from each message's In-Reply-To
fields is no more expensive than other methods which require
examining content of each ancestor message (e.g. those that
compare Subject fields, and/or Date fields).