Daniel Schwabe

• Computer Science
• Professor (Full) at Pontifical Catholic University of Rio de Janeiro

In order to use a value retrieved from a Knowledge Graph (KG) for some computation, the user should, in principle, ensure that s/he trusts the veracity of the claim, i.e., considers the statement as a fact. Crowd-sourced KGs, or KGs constructed by integrating several different information sources of varying quality, must be used via a trust layer....

Online Social Networks (OSNs) have become part of our daily life, contributing to the vast amount of data generated online. The OSNs' data contribute to obtaining information about our society in various areas, such as misinformation, politics, marketing, and engagement metrics. OSN is a comparatively new concept, without a generic model, with prob...

The exploratory search approach recognizes that user queries can be incomplete, inaccurate, and ambiguous. This occurs both because of incomplete domain knowledge by the user or due to implicit assumptions about the context. This ongoing research aims to enrich Knowledge Graphs (KG) to support context-aware exploration through expanded queries. We...

Information exploration tasks are inherently complex, ill-structured, and involve sequences of actions usually spread over many sessions. When exploring a dataset, users tend to experiment higher degrees of uncertainty, mostly raised by knowledge gaps concerning the information sources, the task, and the efficiency of the chosen exploration actions...

Smells are a key sensory experience. They are part of a multi-billion euro industry and gaining traction in different research fields such as museology, art, history, and digital humanities. Until now, a semantic model for describing smells and their associated experiences was lacking. In this paper, we present the Odeuropa data model for olfactory...

Wikidata has been increasingly adopted by many communities for a wide variety of applications, which demand high-quality knowledge to deliver successful results. In this paper, we develop a framework to detect and analyze low-quality statements in Wikidata by shedding light on the current practices exercised by the community. We explore three indic...

In this work, we present a way to model and reason over Knowledge Graphs via an Intuitionistic Description Logic called iALC. We also introduce a Natural Deduction System for iALC to reason over our modelling of the information of the Knowledge Graphs. Furthermore, we apply this modelling to a case study in a context that aims to support the defini...

This paper presents the Outer-Tuning framework, which aims to support the (semi) automatic tuning of relational database systems through a domain-specific ontology. Ontologies have shown themselves to be increasingly promising, adding semantics and standardizing the different terms used in a domain. Thereby, our framework seeks to explain and make...

In this paper we propose a framework characterizing information disorders as disputes of narratives. Such narratives present claims to readers, who must decide whether to accept the statements in the claims as facts. We point out that this process requires establishing connections to moral values, since it has been shown that human decision making...

Wikidata has been increasingly adopted by many communities for a wide variety of applications, which demand high-quality knowledge to deliver successful results. In this paper, we develop a framework to detect and analyze low-quality statements in Wikidata by shedding light on the current practices exercised by the community. We explore three indic...

Database tuning is a task executed by Database Administrators (DBAs) based on their practical experience and on tuning systems, which support DBA actions towards improving the performance of a database system. It is notoriously a complex task that requires precise domain knowledge about possible database configurations. Ideally, a DBA should keep t...

This paper presents the Knowledge Graph Usage framework, which allows the introduction of Knowledge Graph features to support Trust, Privacy, Transparency and Accountability concerns regarding the use of its contents by applications. A real-world example is presented and used to illustrate how the framework can be used. This article also shows how...

Face recognition systems are present in many modern solutions and thousands of applications in our daily lives. However, current solutions are not easily scalable, especially when it comes to the addition of new targeted people. We propose a cluster-matching-based approach for face recognition in video. In our approach, we use unsupervised learning...

Knowledge graphs (KGs) have become the preferred technology for representing, sharing and adding knowledge to modern AI applications. While KGs have become a mainstream technology, the RDF/SPARQL-centric toolset for operating with them at scale is heterogeneous, difficult to integrate and only covers a subset of the operations that are commonly nee...

In the originally published version of chapter 18 the name of Rongpeng Li was misspelled. This has been corrected.

Face recognition systems are present in many modern solutions and thousands of applications in our daily lives. However, current solutions are not easily scalable, especially when it comes to the addition of new targeted people. We propose a cluster-matching-based approach for face recognition in video. In our approach, we use unsupervised learning...

Wikidata and Wikipedia have been proven useful for reason-ing in natural language applications, like question answering or entitylinking. Yet, no existing work has studied the potential of Wikidata for commonsense reasoning. This paper investigates whether Wikidata con-tains commonsense knowledge which is complementary to existing commonsense sourc...

Knowledge graphs (KGs) have become the preferred technology for representing, sharing and adding knowledge to modern AI applications. While KGs have become a mainstream technology, the RDF/SPARQL-centric toolset for operating with them at scale is heterogeneous, difficult to integrate and only covers a subset of the operations that are commonly nee...

Database tuning is a complex task, involving technology-specific concepts. Although they seem to share a common meaning, there are very specific implementations across different DBMSs vendors and particular releases. Database tuning also involves parameters that are often adjusted empirically based on rules of thumb. Moreover, the intricate relatio...

Database tuning is a crucial task to address the performance of information systems that deal with a considerable amount of information stored in databases. Current tuning tools are very platform-specific and do not provide adequate support for the database administrator to reason about performance improvement suggestions. In this paper, we discuss...

This paper presents the KG Usage framework, which allows the introduction of KG features to support Trust, Privacy and Transparency concerns regarding the use of its contents by applications. A real-world example is presented and used to illustrate how the framework can be used.

The Fourth Industrial Revolution (4IR) is characterized by a fusion of technologies, which is blurring the lines between the physical, digital, and biological spheres. In this context, two fundamental characteristics emerge: transparency and privacy. From one side, transparency can be seen as the quality that allows participants of a community to k...

Welcome to this special issue of the Semantic Web (SWJ) journal. The special issue compiles three technical contributions that significantly advance the state-of-the-art in exploration of semantic data using semantic web techniques and technologies.

This paper presents the KG Usage framework, which allows the introduction of KG features to support Trust, Privacy and Transparency concerns regarding the use of its contents by applications. A real-world example is presented and used to illustrate how the framework can be used.

This paper presents the construction of a Knowledge Graph about relations between agents in a political system. It discusses the main modeling challenges, with emphasis on the issue of trust and provenance. Implementation decisions are also presented

This document presents the Configuration Management Ontology Pattern Language (CM-OPL). It is the second version of the CM-OPL, represented by using OPL-ML (Ontology Pattern Language Modeling Language). Therefore, we used a structural model to represent the CM-OPL patterns and structural relationships between them. Also, we present a general proces...

Current society is heavily influenced by the spread of online information, containing all sorts of claims, commonly found in news stories, tweets, and social media postings. Depending on the user, they may be considered "true" or "false", according to the agent's trust on the claim. In this paper, we discuss the concept of content trust and trust p...

A video with a demo of the Synth environment in action.

The Internet and the Web are now an integral part of the way most modern societies, and corresponding political systems, work. We regard Political systems as the formal and informal political processes by which decisions are made concerning the use, production and distribution of resources in any given society. Our focus in on the sets of agents -...

A currently recognized barrier for the wider adoption and dissemination of Semantic Web technologies is the absence of suitable interfaces and tools to allow suitable access by end-users. In a wider context, it has also been recognized that modern day interfaces must deal with a large number of heterogeneity factors, such as varying user profiles a...

The advent of Linked Data is spurring the deployment of applications that use the RDF data model at the information tier. In addition to querying RDF data, there is also the requirement for online updates with suitable concurrency control. Client sessions in Web applications are organized as transactions involving requests that read and write share...

State-of-the-art instance matching approaches do not perform well when used for matching instances across heterogeneous datasets. This shortcoming derives from their core operation depending on direct matching, which involves a direct comparison of instances in the source with instances in the target dataset. Direct matching is not suitable when th...

Development, distribution and use of open source software comprise a market of data (source code, bug reports, documentation, number of downloads, etc.) from projects, developers and users. This large amount of data hampers people to make sense of implicit links between software projects, e.g., Dependencies, patterns, licenses. This context raises...

There has been a large growth of available semi-structured data on the Web, spurred both by governmental requirements for publishing public data, and by private sector, for various purposes. One such large initiative is the Linked Open Data Cloud. An increasingly important activity is to make sense of such published data, often exploring it as a pr...

This book constitutes the refereed proceedings of the 15th International Conference on Web Engineering, ICWE 2015, held in Rotterdam, The Netherlands, in June 2015. The 26 full research papers, 11 short papers, 7 industry papers, 11 demonstrations, 6 posters and 4 contributions to the PhD symposium presented were carefully reviewed and selected fro...

A well-known drawback in building machine learning semantic relation detectors for natural language is the lack of a large number of qualified training instances for the target relations in multiple languages. Even when good results are achieved, the datasets used by the state-of-the-art approaches are rarely published. In order to address these pr...

A well-known drawback in building machine learning semantic relation detectors for natural language is the lack of a large number of qualified training instances for the target relations in multiple languages. Even when good results are achieved, the datasets used by the state-of-the-art approaches are rarely published. In order to address these pr...

Modern day interfaces must deal with a large number of heterogeneity factors, such as varying user profiles and runtime hardware and software platforms. These conditions require interfaces that can adapt to the changes in the <user, platform, environment> triad. The Model-Based User Interface approach has been proposed as a way to deal with these r...

The Role-based Access Control (RBAC) model provides a safe and efficient way to manage access to information of an organization, while reducing the complexity and cost of security administration in large networked applications. However, Web Engineering frameworks that treat access control models as first-class citizens are still lacking so far. In...

Online auction fraud is the most common complaint according to Internet Crime and Complaint Center. Despite that, there are not many published empirical studies about fraud occurrence in online auction sites, and the existing ones mostly target eBay. This lack of research is even worse in Latin American countries. In this paper we present the resul...

Supervised classifiers are limited by the annotated corpora available. Active learning is a way to circumvent this bottleneck, reducing the number of annotated examples required. In this paper, we analyze the benefits of active learning combined with bagging applied to Quotation Start, Noun Phrase Chunking and Text Chunking tasks. We employ query-b...

The interlinking of datasets published in the Linked Data Cloud is a challenging problem and a key factor for the success of the Semantic Web. Manual rule-based methods are the most effective solution for the problem, but they require skilled human data publishers going through a laborious, error prone and time-consuming process for manually descri...

In this paper, show how Linked Data Applications (LDAs) can be designed and implemented using an evolution of the Semantic Hypermedia Design Method, SHDM, and a new development environment supporting it, Synth. Using them, it is possible to take any RDF data available on the Linked Data cloud, extend it with one’s own data, and provide a Web applic...

The Linked Data cloud growth is changing current Web application development. One of the first steps is to determine whether there is information already available that can be immediately reused. A recurring problem being faced in this process is finding and understanding information in such repositories, especially because often their structure is...

One of the most important problems on the semantic web area is the one of trust. The growing exchange of semantic web data raises the need of policies that allow filtering out untrustworthy information. It is necessary, how-ever, to model adequately the concept of trustworthiness, otherwise one may end up with operational trust measures that lack a...

Building applications over Linked Data often requires a mapping between the application model and the ontology underlying the source dataset in the Linked Data cloud. This mapping can be defined in many ways. For instance, by describing the application model as a view over the source dataset, by giving mappings in the form of dependencies between t...

In this paper, we introduce Linkator, an application architecture that exploits semantic annotations for automatically adding links to previously generated web pages. Linkator provides a mechanism for dereferencing these semantic annotations with what it calls semantic links. Automatically adding links to web pages improves the users’ navigation. I...

In this paper, we present a Domain Specific Language (DSL) to specify business and Web transactions in a systematic way, addressing both structural and behavioral perspectives. Our metamodel is based on the reification of transactions, where transactions are modeled as first-class types, supporting attributes, associations, operations and state mac...

Software development tools aimed at end-users tend to employ various forms of visual programming because these users find textual programming very difficult to learn. However, visual programming has known scalability issues. As an alternative, we propose hypertextual programming; a technique that represents the program as hypertext and allows the u...

LinkedTube is a service to create semantic and non-semantic relationships between videos available on services on the Internet (such as YouTube) and external elements (such as Wikipedia, Internet Movie Database, DBPedia, etc). The relationships are defined based on semantic entities obtained through an analysis of textual elements related to the vi...

Fraud is a constant problem for online auction sites. Besides failures in detecting fraudsters, the currently employed methods yield many false positives: bona fide sellers that end up harassed by the auction site as suspects. We advocate the use of human computation (also called crowdsourcing) to improve precision and recall of current fraud detec...

Domain-specific languages (DSLs) have successfully been used for end-user development. However, dealing with language syntax poses significant learning challenges. In this paper, we introduce hypertextual programming, a technique that represents language syntax as hypertext. With this technique, instead of dealing with textual languages, users can...

In this paper we introduce Explorator, a tool for exploring the Semantic Web data by direct manipulation. Explorator implements a model of operations that is supported by a visual interface that enables the user, with minimal knowledge of RDF model, to explore an RDF database without a-priori knowledge of data domain. Consequently, it is well suite...

In this paper we present a preliminary study with Explorator, a tool for exploring RDF data by direct manipulation. Explorator's visual user interface allows users to explore a semi-structured RDF database to both gain knowledge and answer specific questions about a domain, through browsing, search, and exploration mechanisms. Author Keywords Explo...

LinkedTube is a service to create semantic and non-semantic relationships between videos available on services on the Internet (such as YouTube) and external elements (such as Wikipedia, Internet Movie Database, DBPedia, etc). The relationships are defined based on semantic entities obtained through an analysis of textual elements related to the vi...

In this Web 2.0 era, the browsers perform ever-richer graphical interfaces. This paper discusses an approach to web applications interface design that employs the semantic web primitives and it is expressive enough to model most common Rich Internet Application functionalities. It proposes an abstract interface description language and a whole soft...

This article presents Kuaba, a new design rationale representation approach that enables employing design rationale to support reuse of model-based designs, particularly, software design. It is shown that this can be achieved through the adoption of an appropriate vocabulary that allows design rationale representations to be computationally process...

Adaptation techniques often consider applications developed for single users and static scenarios. With the evolution of collaborative environments and the widespread use of mobile technologies, adaptation must take into account the use of systems at any time, anywhere and in a collaborative way. This work suggests a way to extend the Adaptive Sema...

This work has been partly funded by the Austrian Federal Ministry for Education, Science, and Culture, and the European Social Fund (ESF) under grant 31.963/46‐VII/9/2002. The authors would like to thank Andreas Schönbeck and Alexander Knapp for their fruitful comments and contributions to prior versions of this work.

The increasing use of the Web as a software platform together with the advance of technology has given rise to new generations of Web Applications that become more sophisticated almost every year. For example, these applications allow ubiquitous Web access from stationary and mobile computing platforms, they provide individuals and collectivities w...

Many Semantic Wiki Engines have been developed in response to a semi-structured domain of application. Nevertheless these engines take very few advantages of the structured model on their viewing and editing interfaces. In this paper we present HyperDEWiki implementation where we combine Semantic Wiki and model-based Semantic Web Application allowi...

Web Engineering: Modelling and Implementing Web Applications presents the state of the art approaches for obtaining a correct and complete Web software product from conceptual schemas, represented via well-known design notations. Describing mature and consolidated approaches to developing complex applications, this edited volume is divided into th...

Traditional business transactions are established under well-defined contracts, agreed, explicitly or implicitly, by all the parties involved. To support such transactions in the Internet (and in the Web) it is necessary to characterize all of its aspects, such as agents, contracts, roles, relationships, interactions between partners, policies, etc...

In this paper we present a novel approach for designing the interface of rich internet applications. Our approach uses the Abstract Data Views (ADV) design model which allows to express at a high level of abstraction the structure and behaviors of the user interface. Additionally, by using advanced techniques for separation of concerns it allows to...

This paper presents a systematic approach for the authoring of animated multimedia transitions in Web applications, following the current trend of rich interfaces. The transitions are defined based on an abstract interface specification, over which a rhetorical structure is overlaid. This structure is then rendered over concrete interfaces by apply...

In this paper we argue that Web applications are a particular kind of hypermedia application and show how to model their navigational structure. We argue that if we need to design applications combining hypermedia navigation with complex transactional behaviors (as in E-commerce systems), we need a systematic development approach. We present the ma...

Many engineering areas benefit from design reuse, and it is widely accepted that software engineering should be no exception. However, design reuse requires knowledge about the "why" and "how" an artifact was designed the way it was. Design Rationale provides such information. This paper presents Kuaba, a new design rationale representation approac...

This paper presents a development environment and framework that supports a Model Driven Development approach to Web Application Development. In this framework, the models are described through graphical diagrams that are processed by the environment. The main purpose is to ease the development of a web application using Visual Studio .Net 2005 as...

In this work we propose a general purpose architecture for adaptation and meta-adaptation in hypermedia systems, using the Adaptive Semantic Hypermedia Design Model together with the Hypermedia Development Environment, extended to include adaptation. This architecture is model-driven and ontology-based, so data and model may be handled in the same...

There have been several authoring methods proposed in the literature that are model based, essentially following the Model Driven Design philosophy. While useful, such methods need an effective way to allow the application designer to somehow synthesize the actual running application from the specification. In this paper, we describe HyperDe, an en...

In this chapter we present our experience with the Object-Oriented Hypermedia Design Method (OOHDM), a model-based approach for developing Web applications. We first describe the main activities in OOHDM and then we illustrate the application of the method with a simple example, a CD store.

We propose a pluralistic attitude to software specification, where multiple viewpoints/methods are integrated to enhance our understanding of the required system. In particular, we investigate how this process can be supported by heuristics acquired from well-known software specification methods such as Data Flow Diagrams, Petri Nets and Entity Rel...

This workshop is the result of joining the two workshops "Web Services Modeling and Implementation Using Sound Web Engineering Practices" (SMIWEP) and "Methods, Architectures & Technologies for e-Service Engineering" (MATeS), which were originally proposed in conjunction with the ICWE 2006 conference. As a result of the selection process of both wo...

“Evolve or perish” – this is the motto for living systems. Judging by this saying, the Web is alive and well: new sites and business ideas are coming online almost daily and are able to attract millions of users often. The more recently coined term “Web 2.0” summarizes many of the new developments, capturing efforts making the Web more interactive...

Este trabalho apresenta uma estratégia para desenvolver sistemas de informação geográfica, seguindo uma variante do padrão de projeto Modelo- Visão-Controle (MVC). A estratégia adota ontologias para modelar classes de usuário e capturar características adicionais das classes de informação da aplicação. A variante do padrão MVC proposta altera os co...

This paper presents the Kuaba Ontology, a knowledge representation model for Design Rationale described in an ontology definition language. The representation of this model in a specific ontologies specification language, such as OWL or F-Logic, allows attributing semantics to recorded Design Rationale content, and defining rules that enable perfor...

In this paper, we show how one can leverage a Semantic Web appli-cation development environment to define an application that is a Semantic Desktop browser called HyperSD. In addition, special wrappers have been de-fined to allow importing regular desktop objects, such as files, person records, calendar entries, etc… into the semantic desktop acces...

In this paper we propose a modeling and design approach for building physical hypermedia applications, i.e. those mobile applications in which physical and digital objects are related and explored using the hypermedia paradigm. We show that by separating the geographical and domain concerns we gain in modularity, and evolution ease. We first review...

This paper presents the Kuaba Ontology, a vocabulary for Design Rationale described in an ontology definition language that allows attributing semantics to recorded content, and defining rules that enable performing computable operations and inferences on this content. This vocabulary extends the argumentation structure of the Issue Based Informati...

This panel aims to explore the nature of the emerging Web engineering discipline. It will attempt to strongly engage with the issue of whether Web Engineering is currently, and (more saliently) should be in the future, viewed primarily as a technical design discipline with its attention firmly on the way in which Web technologies can be leveraged i...