Abstract. People conventionally refer to an action or occurrence taking place at a certain time at a specific location as an event. This notion is potentially useful for connecting individual facts recorded in the rapidly growing collection of linked data sets and for discovering more complex relationships between data. In this paper, we provide an overview and comparison of existing event models, looking at the different choices they make of how to represent events. We describe a model for publishing records of events as Linked Data. We present tools for populating this model and a prototype "event directory" web service, which can be used to locate stable URIs for events that have occurred, provide RDFS+OWL descriptions and link to related resources.

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Abstract. Semantic descriptions of non-textual media available on the web can be used to facilitate retrieval and presentation of media assets and documents containing them. While technologies for multimedia semantic descriptions already exist, there is as yet no formal description of a high quality multimedia ontology that is compatible with existing (semantic) web technologies. We explain the complexity of the problem using an annotation scenario. We then derive a number of requirements for specifying a formal multimedia ontology before we present the developed ontology, COMM, and evaluate it with respect to our requirements. We provide an API for generating multimedia annotations that conform to COMM.

On the surface, hypermedia is a simpie and natural extension of muitimedia and hypertext: multimedia provides a richness in data types that faciiitates fiexibiiity in expressing Information, whiie hypertext provides a controi structure that supports an eiegant way of navigating through this data in a content-based manner, unfortunateiy. the concepts that apply to collections of static information do not all translate well to complex collections of dynamic information. What does it mean, for example, to foilow a linic in a hypermedia presentation when the source node consists of nonpersistent data? Does the source presentation freeze, does it go away, do parts of it go away? Similarly, how should the synchronization relationships within and among elements in a composite component be defined? is this part of the hypermedia model or part of a data storage or data presentation modei? in our view, a gênerai hypermedia model needs to be able to specify both the conventionai linicbased navigation elements of hypertext and the compiex timing and presentation relationships found in muitimedia presentations. Such a modei is presented here.Intuitively, support for bypermedia can be defined by taking tbe Dexter Hypertext Reference Model [7,8], cmd augmenting it witb multimedia data types witbin its storage layer. The Dexter model provides a facility for creating links within a document, with the links being anchored inside document components. The notions of links, anchors and components are basic to hypertext systems, and since they are not tied to any particular type of implementation or to any particular type of data, integrating them into a hypermedia system would seem to be a straightforward task. (Note that this does not make the task easy: finding a general way to indicate the presence of a link in a dynamic data, or providing means of "clicking" a portion of video or audio, remain difficult and unsolved problems.) Although such a •Carriage of convenience" can provide immediate results, the underlying control assumptions of the Dexter model make it unsuitable for describing and supporting generalized bypermedia documents.' In particular, this approach cannot adequately support complex temporal relationships among data items, specifications that support high-level presentation semantics, or a notion of "information context" that specifies global behavior when a link is followed-all elements that are of fundamental importance in supporting hypermedia.This article presents the Amsterdam Hypermedia Model (AHM), a general framework tbat can be used to describe the basic constructs and actions that are common to a wide range of hypermedia systems. We present the AHM in the context of the Dexter model's hypertext technology and terminology. We do this because hypertext is-in the time scale of information technology-a relatively mature discipline, with a well-defined model of general system bebavior. The AHM is developed as an extension to the Dexter model in order to capitalize on its contributions to understanding hypertext...

We present a web-based diary study on location-based search behavior using a mobile search engine. To capture users' location-based search behavior in a ubiquitous setting, we use a web-based diary tool that collects users' detailed mobile search activity, their location and diary entries. This method enables us to capture users' explicit behavior (query made), their implicit intention (motivation behind search) and the context (spatial, temporal, and social) in which the search was carried out. The results of the study show that people tend to stick closely to regularly used routes and regularly visited places, e.g. home and work. We also found that most location-based searches are conducted while in the presence of others. We summarize our findings and offer suggestions to improve location-based search by using features such as location-based service mash-ups.

We present the user interface to the CMIF authoring environment for constructing and playing multimedia presentations. The CMIF authoring environment supports a rich hypermedia document model allowing structure-based composition of multimedia presentations and the specification of synchronization constraints between constituent media items. An author constructs a multimedia presentation in terms of its structure and additional synchronization constraints, from which the CMIF player derives the precise timing information for the presentation.We discuss the advantages of a structured approach to authoring multimedia, and describe the facilities in the CMIF authoring environment for supporting this approach. The authoring environment presents three main views of a multimedia presentation: the hierarchy view is used for manipulating and viewing a presentation's hierarchical structure; the channel view is used for managing logical resources and specifying and viewing precise timing constraints; and the player for playing the presentation.We present the authoring environment in terms of a short example: constructing a walking tour of Amsterdam.

First generation Web-content encodes information in handwritten (HTML) Web pages. Second generation Web content generates HTML pages on demand, e.g. by filling in templates with content retrieved dynamically from a database or transformation of structured documents using style sheets (e.g. XSLT). Third generation Web pages will make use of rich markup (e.g. XML) along with metadata (e.g. RDF) schemes to make the content not only machine readable but also machine processable ---a necessary pre-requisite to the Semantic Web.While text-based content on the Web is already rapidly approaching the third generation, multimedia content is still trying to catch up with second generation techniques. Multimedia document processing has a number of fundamentally different requirements from text which make it more difficult to incorporate within the document processing chain. In particular, multimedia transformation uses different document and presentation abstractions, its formatting rules cannot be based on text-flow, it requires feedback from the formatting back-end and is hard to describe in the functional style of current style languages.We state the requirements for second generation processing of multimedia and describe how these have been incorporated in our prototype multimedia document transformation environment, Cuypers. The system overcomes a number of the restrictions of the text-flow based tool sets by integrating a number of conceptually distinct processing steps in a single runtime execution environment. We describe the need for these different processing steps and describe them in turn (semantic structure, communicative device, qualitative constraints, quantitative constraints, final form presentation), and illustrate our approach by means of an example. We conclude by discussing the models and techniques required for the creation of third generation multimedia content.

Abstract. Traditionally, research in applying Semantic Web technology to multimedia information systems has focused on using annotations and ontologies to improve the retrieval process. This paper concentrates on improving the presentation of the retrieval results. First, our approach uses ontological domain knowledge to select and organize the content relevant to the topic the user is interested in. Domain ontologies are valuable in the presentation generation process, because effective presentations are those that succeed in conveying the relevant domain semantics to the user. Explicit discourse and narrative knowledge allows selection of appropriate presentation genres and creation of narrative structures, which are used for conveying these domain relations. In addition, knowledge of graphic design and media characteristics is essential to transform abstract presentation structures into real multimedia presentations. Design knowledge determines how the semantics and presentation structure are expressed in the multimedia presentation. In traditional Web environments, this type of design knowledge remains implicit, hidden in style sheets and other document transformation code. Our second use of Semantic Web technology is to model design knowledge explicitly, and to enable it to drive the transformations needed to turn annotated media items into structured presentations.