Places ("downtown"), spatial objects ("highway 1") and localized events ("hurricane Katrina"), are commonly referred to in the Semantic Web. They serve to search for and link to information across domains. Spatial reference systems, such as WGS84¹⁾, allow for representing such references as points or regions. This makes them amenable not only for mapping, but also for powerful location-based querying and computing.

Spatial references are also fundamental in embodied cognition and robotics. Egocentric and allocentric spatial reference frames underlie robot learning and interaction. Decades of research in cognitive robotics highlight the role of social interaction, joint attention, language games, and visual discrimination games in establishing referents for symbols. The most well-known experiment is that of the Talking Heads. Spatial relations, such as right, front, left, behind, serve to name and identify other objects in a self-organizing vocabulary. Affordance-based cognition is a source of spatial reference in robots. However, so far, this research is only loosely connected to information science and the Semantic Web.

Existing options to localize information in the Semantic Web and in Robotics through coordinate systems cover only limited cases of spatial reference. Humans localize referents in space in many ways, based on different tasks and spatial competencies. For example, the location of a workplace may be linked to people, tasks, and infrastructures. It can be specified in terms of a coordinate system or, alternatively, in terms of containment, connectedness and accessibility in a building; yet another option is to specify it by the possibility to perform certain activities, such as sitting or reading and writing at the workplace.

This Dagstuhl Seminar will bring together leading international researchers from the Semantic Web, Spatial Cognition, Geo-informatics and Cognitive Robotics areas to work on the application, synthesis, formal construction, extension, and use of spatial reference systems, identifying challenges and research opportunities.

A closer connection of Cognitive Robotics and Semantic Web would provide particularly attractive options for research. For example, robot reference systems can be used in order to describe things accessible in the world, and Semantic Web technology to publish those descriptions for better information access. And vice versa, spatial referents and descriptions in the Semantic Web may guide robots towards accessible things in the world. Robots may function as surrogates of human observers and actors exchanging information on the Web of Data encoded in terms of their reference systems.

The following questions will be dealt with: 1. How can spatial reference systems improve search and integration in the Semantic Web? 2. How can spatial reference systems used in Robotics and the Semantic Web be made more adequate, flexible, and powerful? 3. How can the appropriateness of spatial reference systems be tested formally and empirically? Which spatial calculi and other formalisms support computations with spatial reference systems? 4. How can empirical evidence of spatial reference systems be found and in what sources? Dialogue corpora about directions and orientation? Narrative structures involving spatial referents? 5. How can we construct new kinds of reference systems for indoor and outdoor places? 6. What is the role of action-perception cycles, action simulation, social interaction, and joint attention in establishing spatial reference?

In order to focus discussions and make progress on each of these questions, the seminar will be organized around the use case of building an indoor mapping system for office workplaces. This system should allow for establishing place referents by various means, including robot and human interaction, in order to localize work resources, such as people, tasks, rooms, and activities.

1. The world geodetic system https://en.wikipedia.org/wiki/World_Geodetic_System, a standard reference ellipsoid and coordinate frame for encoding locations on the earth surface.

• Brandon Bennett (University of Leeds, GB) [dblp]
• Mehul Bhatt (Universität Bremen, DE) [dblp]
• Sasa Bodiroza (HU Berlin, DE) [dblp]
• Martin V. Butz (Universität Tübingen, DE) [dblp]
• Nicholas Chrisman (RMIT University - Melbourne, AU) [dblp]
• Helen Couclelis (University of California - Santa Barbara, US) [dblp]
• Anne Cregan (Intersect - Sydney, AU) [dblp]
• Max J. Egenhofer (University of Maine, US) [dblp]
• Andrew U. Frank (TU Wien, AT) [dblp]
• Christian Freksa (Universität Bremen, DE) [dblp]
• Aldo Gangemi (CNR - Rome, IT) [dblp]
• Giancarlo Guizzardi (UFES - Vitoria, BR) [dblp]
• Verena V. Hafner (HU Berlin, DE) [dblp]
• Pascal Hitzler (Wright State University - Dayton, US) [dblp]
• Werner Kuhn (University of California - Santa Barbara, US) [dblp]
• Bruno Lara Guzman (National University of Mexico, MX) [dblp]
• Vivien Mast (Universität Bremen, DE) [dblp]
• Mihoko Niitsuma (Chuo University, JP) [dblp]
• Kai-Florian Richter (Universität Zürich, CH) [dblp]
• Katharina J. Rohlfing (Universität Bielefeld, DE) [dblp]
• Yulia Sandamirskaya (Ruhr-Universität Bochum, DE) [dblp]
• Thomas Scharrenbach (Universität Zürich, CH) [dblp]
• Simon Scheider (Universität Münster, DE) [dblp]
• Michael Spranger (Sony - Tokyo, JP) [dblp]
• Stephan Winter (The University of Melbourne, AU) [dblp]
• Stefan Wölfl (Universität Freiburg, DE) [dblp]
• Diedrich Wolter (Universität Bamberg, DE) [dblp]