This paper describes a simple discourse parsing and analysis algorithm that combines a formal
underspecification utilising discourse grammar with Information Retrieval (IR) techniques.
First, linguistic knowledge based on discourse markers is used to constrain a totally underspecified discourse representation. Then, the remaining underspecification is further specified
by the computation of a topicality score for every discourse unit. This computation is done via
the vector space model. Finally, the sentences in a prominent position (e.g. the first sentence
of a paragraph) are given an adjusted topicality score. The proposed algorithm was evaluated
by applying it to a text summarisation task. Results from a psycholinguistic experiment,
indicating the most salient sentences for a given text as the ‘gold standard’, show that the
algorithm performs better than commonly used machine learning and statistical approaches
to summarisation.