RST* text mapping *Rhetorical Structure Theory

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RST text mappingRhetorical Structure
Theory
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The text 1) Lactose and Lactase 2) Lactose is
milk sugar 3) the enzyme lactase breaks it
down. 4) For want of lactase most adults cannot
digest milk. 5) In populations that drink milk
the adults have more lactase, perhaps through
natural selection. 6) Norman Kretchmer,
Scientific American, page 70, October 1972.
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The text 1) Lactose and Lactase 2) Lactose is
milk sugar 3) the enzyme lactase breaks it
down. 4) For want of lactase most adults cannot
digest milk. 5) In populations that drink milk
the adults have more lactase, perhaps through
natural selection. 6) Norman Kretchmer,
Scientific American, page 70, October 1972. RST
Analysis from the RST web site (http//www.sfu.ca/
rst) This abstract is nearly half background
information. One of the reasons that
backgrounding is not signalled by its own
distinct signal (such as a conjunction) may be
that such a signal would in effect say that the
author thought the reader would not know this
information. Some readers might find that mildly
condescending if it were made explicit. Backgroun
ding is seldom signalled explicitly.
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NucleusSatellite relations The most frequent
structural pattern is that two spans of text
(virtually always adjacent, but exceptions can be
found) are related such that one of them has a
specific role relative to the other. RST says
that the nucleus is more essential to the text
than the satellite
Relation Name Nucleus Satellite
Evidence claim evidence for the claim
Background text whose understanding is being facilitated text for facilitating understanding
Elaboration basic information additional information
Preparation text to be presented text which prepares the reader to expect and interpret the text to be presented.
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Multinuclear relations There are also relations
that do not carry a definite selection of one
nucleus.
Relation Name Span a Span b
Contrast
Joint
List
Sequence
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More RST relations