coherence relations between large spans of text

[Eduard Hovy]

Hello Ken,

At 8:44 AM +0600 4/14/09, Ken Keyes wrote:
>I am intrigued (again) by Mick's comment about modeling the schemas for
>texts.
>...So, mononuclear relations may not be a good way of modeling. Mick, are you
>saying that multinuclear relations are more appropriate?

It's probably helpful to remember the difference between schemas and relations:

Schemas are generally larger frameworks, consisting of several 
elements in [often fixed] sequence, in which each element has a 
function that contributes [equally] to the overall whole.  The 
functions may themselves be structures (hence, filled by other 
schemas).

Relations are smaller, linking [generally] only two pieces of text 
together.  Generally, one of the two is primary (in RST called the 
Nucleus).  But a few RST relations (notably Joint) were defined as 
multi-nuclear: not two, but many, components, all co-equal.  One 
doesn't have to care about the fact that one of the two branches of a 
relation is dominant, but taking this into account allows you to do 
things like shorten the text (dropping out the non-dominant parts), 
identify the most 'important' parts of a text, etc.

Note that one can often 'decompose' a schema into its constituent 
(tree of) relations.  In this view a schema is nothing more than a 
frozen stereotypical structure of relations.

Regards,
E

-- 
Eduard Hovy
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