Relations that are seldom or never signale

[Bill Mann]

I want to respond to Alistair Knott's very interesting message, reproduced
below. (Sorry, this mail processor does not do >.)

I will edit in remarks marked WM: , mark his with AK: , and delete some things.

______________________________ Reply Separator _________________________________

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2) Now to some specific analyses given. John Bateman's example is a prima
facie case where a BACKGROUND relation is signaled using a connective
(which I was claiming never happens):

> (1)     Look, you'll just have to go with him to the store.
> (2)     Since his foot is broken, he can't go by himself.

> Background? (2a,2b) with 2b as nucleus.

WM: It is possible, and arguably is seen here, that "Since" is not signaling the
Background relation.  For example, in a text just made up for the purpose, we
could find:

(a)     Since Bush is the son of a former President,
(b)     He needs to keep up his image so that he won't be an international
embarrassment.

I can say that the Background relation is the best fit here, the one that I
think plausibly the author intended, and still say that Since signals logical
consequence of some sort.

"Since" would then be parallel to "Although" in position:  Since A, B.
Although A, B.  Both of them allow both A and B to be affirmed, but with
differents stances by the writer.

What is signaled by such a lexical item need not be the RST relation.

This possibility creates difficulties if we want to assemble a corpus of RST
relations and their signals.  It is not enough to find a lexical item or phrase
in just the right place where the relation surely is present.  We must also
judge each case to say whether the item is representing the relation in any way.

It's a shame that it cannot be more mechanical, but I don't see any way around
that bit of judging.

AK: As John says, it's hard to distinguish between Background, Justify, and
Evidence here.

WM: Let me make an absolutely trivial point and then develop some
significance for it.   In cases where no signal is present, it cannot be
the conjunctive word or phrase that distinguishes between relations.  All
of relations on that list of 12 are not explicitly distinguished most of
the time.  And every relation can be unsignaled in certain texts.

The normal case, the high frequency case, is for a relation to be
unsignaled.  So developing this sort of text structure on grounds of form
alone is hopeless.  If we have some indirect (not textually explicit)
reason to believe that a relation is present, then generally we will need
to explain that on grounds other than the forms.  This group has not
discussed "Relational Propositions" in RST, but they provide one line of
such evidence.

To me, Justify and Background are quite distinct.  Justify involves the
speaker's right to express something.  Background involves the possibility
that the audience may lack some information that is vital or very helpful
for interpreting something.

I don't see how Justify fits in the texts cited below, because there seem
to be no issues of the speaker's right to express anything.

AK: Daniel Marcu gave two texts in which he suggested a background or
justification relation holds between large text spans, and in which the
notion of focus wouldn't be helpful in explicating the relationship
between the spans. (The texts are repeated below.)

In all three texts, it's interesting that there are difficulties in
distinguishing between the RST relations of background and justification.
So there are two separate questions: (i) Is the relation in question
background or not? (ii) If it is background, (a) is it signaled by a
connective? and (b) can a notion of focus continuity be used to explain
the coherence between the two spans?  I must admit that I find it
extremely difficult in practice to use the definitions given in classical
RST to distinguish between background and justification relations. On the
other hand, I think the question of whether or not a particular connective
would be suitable to signal a particular relation is much easier to
determine: at least some of the time the text already contains a
connective, and in the absence of a connective, the question of whether
one would be appropriate draws on the kind of judgment we make all the
time as writers/speakers. For instance, it seems quite clear that we could
use a connective like `because' to signal the relation in Daniel's `Flu
stopper' text:

> [Running nose. Raging fever. Aching joints. Splitting headache. Are
> there any poor souls suffering from the flu this winter who haven't
> longed for a pill to make it all go away? Relief may be in
> sight] , BECAUSE
> [Researchers at Gilead Sciences, a pharmaceutical company in
> Foster City, California, reported last week in the Journal of the
> American Chemical Society that they have discovered a compound that
> can stop the influenza virus from spreading in animals. Tests on
> humans are set for later this year.]

And I really think it's difficult to use `because', or any other
connective, in Daniel's other example text.

>         [The lore of ancient Greece recalls an Olympic athlete who was
> determined to become the strongest person in the world. Every day
> Milon of Croton would pick up a calf, raise it above his head and
> carry it around a stable. As the calf grew, so did Milon's strength,
> until eventually he was able to lift the full-grown cow.
>
>         Milon, who won the wrestling contest five times,
> intuitively grasped one of the basic tenets of contemporary sports
> science.] [Progressive resistance training - the stressing of muscles
> with steadily increasing loads - is something well understood by the more
> than 10,000 athletes from 197 countries who will go to Atlanta, Ga.,
> next month for the centennial of the modern Olympic Games. (...)

This is not just because the spans are large: as Bill Mann noted, we can
signal relations using phrases or even clauses, such as `This is because'
or `This is for the following reason', but no phrases of this sort seem to
fit either. I'd argue that this points up an interesting difference
between the Olympic text and the other two. There has got to be something
that explains why connectives are suitable in two cases and not in the
third. This is true quite independently of any discussion about which RST
relation should be used in analysing the texts. However, given the
difficulty of distinguishing between background and justification going by
the definitions in classical RST, I think it might make sense to take the
question of whether or not a connective can be used as a diagnostic for
whether the relation is background or not. Of course, this means it would
no longer be an empirical result to say that background relations cannot
be signaled with connectives: it'd be true by definition. The interesting
research question would then be to look for a new definition for
background and justification which (a) makes the two easier to
distinguish, and (b) accounts for the data about the places where a
connective can and cannot be used. Again, this would be a significant
departure from RST, whose relations are explicitly defined with no
reference to surface linguistic features.

WM:  Insertability of particular lexical items, as a test of relations, is
certainly outside of the methods and spirit of RST.  But perhaps we could
satisfy AK as follows:  Insertability of particular conjunctions can be a
clarifier of the plausibility of particular relations holding, and thus a
tool for the observer to use in deciding whether to affirm a relation
between two spans.  It's not a test in the same sense, but I think it
fits.

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AK: Incidentally, you have to sympathise with the cow in Daniel's Olympic
story. It must have wondered what the world was coming to being lifted up
and carried around the stables all day.

WM: Perhaps, like conjunctions, it's something you grow up with.

AK: In any case, as I said in my original message, I'm wary of using the success
of a generation system implementing a certain theory of discourse as strong
support for the theory.

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WM: Yes.  But having been there, I know that the process of implementation
rejects great hordes of process and knowledge ideas that were initially
attractive.  It is fine as a kind of first filter.

Thank you, Alistair, for your message.  I am sure we have not finished sorting
these things out.

Bill Mann