Constructive Reasoning for Semantic Wikis

One of the main design goals of social software, such as wikis, is to support and facilitate interaction and collaboration. This dissertation explores challenges that arise from extending social software with advanced facilities such as reasoning and semantic annotations and presents tools in form of a conceptual model, structured tags, a rule language, and a set of novel forward chaining and reason maintenance methods for processing such rules that help to overcome the challenges. Wikis and semantic wikis were usually developed in an ad-hoc manner, without much thought about the underlying concepts. A conceptual model suitable for a semantic wiki that takes advanced features such as annotations and reasoning into account is proposed. Moreover, so called structured tags are proposed as a semi-formal knowledge representation step between informal and formal annotations. The focus of rule languages for the Semantic Web has been predominantly on expert users and on the interplay of rule languages and ontologies. KWRL, the KiWi Rule Language, is proposed as a rule language for a semantic wiki that is easily understandable for users as it is aware of the conceptual model of a wiki and as it is inconsistency-tolerant, and that can be efficiently evaluated as it builds upon Datalog concepts. The requirement for fast response times of interactive software translates in our work to bottom-up evaluation (materialization) of rules (views) ahead of time – that is when rules or data change, not when they are queried. Materialized views have to be updated when data or rules change. While incremental view maintenance was intensively studied in the past and literature on the subject is abundant, the existing methods have surprisingly many disadvantages – they do not provide all information desirable for explanation of derived information, they require evaluation of possibly substantially larger Datalog programs with negation, they recompute the whole extension of a predicate even if only a small part of it is affected by a change, they require adaptation for handling general rule changes. A particular contribution of this dissertation consists in a set of forward chaining and reason maintenance methods with a simple declarative description that are efficient and derive and maintain information necessary for reason maintenance and explanation. The reasoning methods and most of the reason maintenance methods are described in terms of a set of extended immediate consequence operators the properties of which are proven in the classical logical programming framework. In contrast to existing methods, the reason maintenance methods in this dissertation work by evaluating the original Datalog program – they do not introduce negation if it is not present in the input program – and only the affected part of a predicate’s extension is recomputed. Moreover, our methods directly handle changes in both data and rules; a rule change does not need to be handled as a special case. A framework of support graphs, a data structure inspired by justification graphs of classical reason maintenance, is proposed. Support graphs enable a unified description and a formal comparison of the various reasoning and reason maintenance methods and define a notion of a derivation such that the number of derivations of an atom is always finite even in the recursive Datalog case. A practical approach to implementing reasoning, reason maintenance, and explanation in the KiWi semantic platform is also investigated. It is shown how an implementation may benefit from using a graph database instead of or along with a relational database

Aprendizagem colaborativa com o uso de wikis: um estudo de caso em diferentes ambientes formais (sala de aula, laboratório e outdoor) numa turma de biologia e geologia do ensino secundário

Doutoramento em Multimédia em EducaçãoEste estudo teve como finalidade a análise da dinâmica colaborativa estabelecida e dos documentos elaborados coletivamente pelos alunos numa Wiki, articulados com as estratégias desenvolvidas em diferentes ambientes formais de ensino e aprendizagem: sala de aula, laboratório e outdoor. A análise foi contextualizada em dois referenciais teóricos: ciclo Wiki (Davies, 2004) e Teoria da Atividade Histórico-Cultural (Vygotsky, 1978; Engeström, 2001). Do ponto de vista metodológico foi adotado o estudo de caso para fazer uma análise profunda da dinâmica colaborativa, utilizando vários instrumentos de recolha de dados. Concluiu-se que o grupo de alunos estudado manteve globalmente o compromisso na construção da Wiki, decorrente de vários fatores previstos por Davies (2004): compreensão técnica e concetual do trabalho Wiki, confiança na comunidade, na tecnologia, bem como nos conteúdos publicados. De acordo com este modelo, estes fatores contribuiram de forma retroativa para as contribuições regulares e para manter o valor individual e social da Wiki. A Teoria da Atividade Histórico-Cultural permitiu o reconhecimento de numerosas contradições no sistema de atividade Wiki, quando este se encontrava em interação com atividades desenvolvidas noutros ambientes de aprendizagem: primárias, secundárias, terciárias e quaternárias. A colaboração dos alunos nas atividades Wiki foi variável ao longo do tempo e dentro de cada atividade. As evidências resultantes da triangulação dos dados mostraram, neste caso, a co-existência de dois grupos de alunos com visões distintas do trabalho coletivo, uma perspetivada na literatura como cooperativa e a outra como colaborativa. O learning design aplicado não foi suficiente para neutralizar esta clivagem. No que concerne aos produtos coletivos desenvolvidos pelo grupo estudado, constatou-se que os alunos, somente de forma parcial, conseguiram desenvolver e expressar as suas próprias ideias por três razões fundamentais: (i) persistência e domínio de informação factual previamente lecionada nas aulas presenciais; (ii) redução da contribuição e da intensidade colaborativa dos alunos em páginas Wiki de maior exigência cognitiva e (iii) persistência nas páginas Wiki de informação copiada pelos alunos a partir de outros sítios da Web.The aim of this research was the analysis of the collaborative dynamic and the collective documents done by the students within a Wiki, structured in accordance with the strategies developed in different learning environments, such as the classroom, lab and outdoors. The analysis was contextualized in two theoretical frameworks: Wiki cicle (Davies, 2004) and cultural–historical activity theory (Vygotsky, 1978; Engeström, 2001). The methodology chosen was a case study in order to make a deeper analysis of the collaborative dynamics, using different instruments to gather data. The conclusion was that the students in the case study adhered to building the Wiki, in accordance to several factors as foreseen by Davies (2004): concetual and technical understanding of the work pertaining the Wiki, trust in the community and in the technology, as well as in the published materials. According to this model these factors helped in a retroactive way towards the periodical contributions and also to keep the individual and social value of the Wiki. The Historical and Cultural Activity Theory allowed the recognition of several contradictions within the Wiki activity system whenever it interacted with other activities developed in another learning environment: first, second, third and fourth. Students’ collaboration in Wiki’s activities differed throughout the study as well as within each activity. The evidence that resulted from analyzing the data showed, in this case, the co-existence of two students’ groups with different approaches to collective work. One was based on literature as cooperative and another as collaborative. The learning design applied was not enough to dissipate this difference. Regarding the collective products developed by the group that was studied, it was noted that the students only partially were able to develop and express their own ideas, due to three main reasons: (i) resilience and an overall knowledge of factual information taught previously in the classroom, (ii) a lesser demand on cognitive skills regarding the intensity and contribution from the students in Wiki pages and (iii) persistence of Web copied information by the students without credits on the Wiki pages

Integration of Communities into Process-Oriented Structures

This article aims at the integration of communities of practice into work processes. Linear structures are often inappropriate for the execution of knowledge intensive tasks and work processes. The latter are characterized by non-linear sequences and dynamic, social interaction. But for the work in communities of practice the leading path, that is needed for structuring the work, is often missing. Our article exposes the requirements in order to integrate the dynamic, social processes of the knowledge generation in communities of practice with formal described knowledge intensive processes. For the support of communities the Wiki-concept is introduced. In order to integrate communities into process structures a concept for an appropriate interface is presented. On the basis of this interface concept an information retrieval algorithm is used to connect the process-oriented structures with community-oriented structures. The prototype realisation of this concept is shown by a short example