A Constraint-Based Graph Visualisation Architecture for Mobile Semantic Web Interfaces Daniel Sonntag and Philipp Heim German Research Center for Artificial Intelligence 66123 Saarbr¨ ucken, Germany sonntag@dfki.de, heim@interactivesystems.info Abstract. Multimodal and dialogue-based mobile interfaces to the Se- mantic Web offer access to complex knowledge and information struc- tures. We explore more fine-grained co-ordination of multimodal pre- sentations in mobile environments by graph visualisations and naviga- tion in ontological RDF result structures and multimedia archives. Se- mantic Navigation employs integrated ontology structures and leverages graphical user interface activity for dialogical interaction on mobile de- vices. Hence information visualisation benefits from the Semantic Web. Constraint-based programming helps to find optimised multimedia graph visualisations. We report on the constraint-formulisation process to op- timise the visualisation of semantic-based information on small devices and its integration in a distributed dialogue system. 1 Introduction For every specific type of information there are certain categories of visual rep- resentations that are more suitable than others. The use of a graph for the visualisation of information has the advantage that it can capture a detailed knowledge structure. Therefore graphs are suitable for conveying semantic rela- tions between individual information items and for providing an understanding of the overall information structure. We aim to display information that stem from semantic RDF 1 structures and explore if the implicit graph structure in the RDF data can be used for the knowledge visualisation process, especially on mobile devices. By additional graph presentations of answers in a linguistic question answering scenario, the user would become more engaged in the di- alogue, navigate through the incrementally presented result space, and would be encouraged to pose follow-up questions in natural language. The challenge we address is the intuitive navigation in a semantically organised information space on small interaction devices. Using RDF structures for graph representa- tions can improve the users’ understanding of certain information pieces and the relations between these pieces. The second aim is to produce evidence for this hypothesis by implementing and evaluating mobile Semantic Web interfaces and applying direct structure mapping from RDF graphs toward their multimedia visualisations. 1 Resource Description Framework, http://www.w3.org/RDF/