page_title: Rhetorical structure theory
section_title: Rhetorical relations
hierarchical_section_title: Rhetorical structure theory / Rhetorical relations
caption_attribution_description: English: Its a diagram of an RST analysis
context_page_description: Rhetorical structure theory was originally developed by William Mann and Sandra Thompson of the University of Southern California's Information Sciences Institute and defined in a seminal paper in 1988. This theory was developed as part of studies of computer based text generation. Natural language researchers later began using RST in text summarization and other applications. RST addresses text organization by means of relations that hold between parts of text. It explains coherence by postulating a hierarchical, connected structure of texts. In 2000, Daniel Marcu, also of ISI, demonstrated that practical discourse parsing and text summarization also could be achieved using RST.
context_section_description: Rhetorical relations or coherence relations or discourse relations are paratactic (coordinate) or hypotactic (subordinate) relations that hold across two or more text spans. It is widely accepted that notion of coherence is through text relations like this. RST using rhetorical relations provide a systematic way for an analyst to analyse the text. An analysis is usually built by reading the text and constructing a tree using the relations. The following example is a title and
  summary, appearing at the top of an article in Scientific American magazine (Ramachandran and Anstis, 1986). The original text, broken into numbered units, is:
  [Title:] The Perception of Apparent Motion
  [Abstract:] When the motion of an intermittently seen object is ambiguous
  the visual system resolves confusion
  by applying some tricks that reflect a built-in knowledge of properties of the physical world
  In the figure, numbers 1,2,3,4 show the corresponding units as explained above.
  The fourth unit and the third unit form a relation "Means". The fourth unit is the essential part of this relation, so it is called the nucleus of the relation and third unit is called the satellite of the relation. Similarly second unit to third and fourth unit is forming relation "Condition". All units are also spans and spans may be composed of more than one unit.
caption: Diagram of RST analysis
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