ABSTRACT
This chapter presents the plot-unit representation and the summarization process and gains more insight into the phenomena of human and computer understanding. Plot units are constructed from smaller entities called affect states. The second component of plot units and affect state maps are causal links. Causal links always connect two affect states and indicate the different relationships that exist between various affect state pairs. The plot-unit system resides on one level of a multilayered representational scheme. In its role of text planner, PRECIS decides what should be mentioned and what should be left for the reader to infer. PRECIS associates different planning rules with different plot units or plot-unit combinations. Plot units work well both as a computer program and as a cognitive model: Plot-Unit Graph Generator (PUGG) is able to identify the key concepts in a story and its output agrees well with summaries produced by human subjects.
