From Topic Networks to Distributed Cognitive Maps: Zipfian Topic Universes in the Area of Volunteered Geographic Information

Figure 2

Schema of mapping texts onto hierarchically organized topic networks: words, sentences, and texts describing a certain thematic frame (e.g., a place as the central topic of a city wiki) are mapped onto a topic hierarchy as an example of a so-called generalized tree [56, 57]. Based on kernel links of thematic specialization, the topics are organized hierarchically, whereby this organization is superimposed by up- and downward cross-references. Dashed links are inferred as a result of modeling the thematic networking of input words, sentences, or texts. As we assume that the underlying topic model has been trained by means of a reference corpus (see Definition 2), each topic is associated with a distribution of lexical elements of that are preferably used to manifest this topic (see the types in relation to the topics in Figure 1). This preference relation may be extended to higher-level units such as sentences.