Ontological database management systems are a powerful tool that combine traditional database techniques with ontological reasoning methods. In this setting, a classical extensional database is enriched with an ontology, or a set of logical assertions, that describe how new, intensional knowledge can be derived from the extensional data. Conjunctive queries are therefore answered against this combined knowledge base of extensional and intensional data. Many languages that represent ontologies have been introduced in the literature. In this thesis we will focus on existential rules (also called tuple-generating dependencies or Datalog^± rules), and three established languages in this area, namely guarded-based rules, sticky rules and weakly-acyclic rules. The main goal of the thesis is to enrich these languages with non-deterministic constructs (i.e. disjunctions) and investigate the complexity of the answering conjunctive queries under these extended languages. As is common in the literature, we will distinguish between combined complexity, where the database, the ontology and the query are considered as input, and data complexity, where only the database is considered as input. The latter case is relevant in practice, as usually the ontology and the query can be considered as fixed, and are usually much smaller than the database itself. After giving appropriate definitions to extend the considered languages to disjunctive existential rules, we establish a series of complexity results, completing the complexity picture for each of the above languages, and four different query languages: arbitrary conjunctive queries, bounded (hyper-)treewidth queries, acyclic queries and atomic queries. For the guarded-based languages, we show a strong 2EXPTIME lower bound for general queries that holds even for fixed ontologies, and establishes 2EXPTIME-completeness of the query answering problem in this case. For acyclic queries, the complexity can be reduced to EXPTIME, if the predicate arity is bounded, and the problem even becomes tractable for certain restricted languages, if only atomic queries are used. For ontologies represented by sticky disjunctive rules, we show that the problem becomes undecidable, even in the case of data complexity and atomic queries. Finally, for weakly-acyclic rules, we show that the complexity increases from 2EXPTIME to coN2EXPTIME in general, and from tractable to coNP in case of the data complexity, independent of which query language is used. After answering the open complexity questions, we investigate applications and relevant consequences of our results for description logics and give two generic complexity statements, respectively, for acyclic and general conjunctive query answering over description logic knowledge bases. These generic results allow for an easy determination of the complexity of this reasoning task, based on the expressivity of the considered description logic.

The goal of this thesis is to create a dependency treebank for Yorùbá, a language with very little pre-existing machine-readable resources. The treebank follows the Universal Dependencies (UD) annotation standard, certain language-specific guidelines for Yorùbá were specified. Known techniques for porting resources from resource-rich languages were tested, in particular projection of annotation across parallel bilingual data. Manual annotation is not the main focus of this thesis; nevertheless, a small portion of the data was verified manually in order to evaluate the annotation quality. Also, a model was trained on the manual annotation using UDPipe.

Background. Over the years, agile software development has become increasingly popular in the software industry. One of the reasons is that agile development addressed the needs of the organisations better than the traditional models, such as the waterfall model. However, the textbook version of agile development still leaves something to be desired. This could be learnt by observing the implementation of agile methods/frameworks in the industry. The teams often customize agile methods to suit their context-specific needs. When teams in the industry decide to adopt the agile way of working, they are confronted by a choice¾either they have to implement all the agile practices at a time or adopt them over the time. The former choice has shown to come with risks and, therefore, was found that practitioners generally preferred the latter. However, agile practices are not independent, they have dependencies amongst them. A new approach to agile development emerged in the recent years known as Agile Maturity Models (AMMs). AMMs claim to offer a better path to agile adoption. In AMMs, the practices are typically introduced gradually in a particular order. However, these AMMs are multifarious and haven’t been sufficiently evaluated¾especially in the industry practice. Thus, they need to be evaluated in order to understand their relevance in the industry.   Objectives. The goal is to evaluate the relevance of AMMs in the industry. By finding relevant AMMs, they could be used to alleviate the formation of agile teams and contribute toward their smoother functioning. By finding those that aren’t, this research could act as a cautionary to those practitioners who could potentially implement these AMMs and risk failure. The objectives are: identifying the agile practice dependencies in the AMMs; finding the agile practice dependencies in an agile team by conducting a case study in the industry; comparing the dependencies from the case study with those in the AMMs.
   Methods. The agile maturity models were identified and analysed. A case study was conducted on an agile team to identify the dependencies between the agile practices in the industry practice. Semi-structured interviews were conducted with members of the agile team. Qualitative coding was used to analyse the collected data. The dependencies from the case study were compared with the AMMs to achieve the aim of this research.   Results. It was found that dependencies between individual agile practices in the AMMs were almost never possible to be found. However, practices suggested in each maturity levels were derived. Hence, the dependencies were found in the maturity-level level. From the case study, 20 agile practice dependencies were found. 7/8 AMMs were found to be not relevant. 1 AMM couldn’t be evaluated as it heavily relied on the practitioner’s choices.   Conclusions. The researchers could use the evaluation method presented in this thesis to conduct more such evaluations. By doing so, the dynamics present in the industry teams could be better understood. On their basis, relevant AMMs could be developed in the future. Such AMMs could help practitioners leverage agile development.

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No. of bitstreams: 1 milenecristinedecastroteixeira.pdf: 1373244 bytes, checksum: 7bba0e38b23013ba9fba481b4563dce8 (MD5) Previous issue date: 2012-02-29 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este estudo investiga as capacidades de abstração e generalização de padrões linguísticos nas etapas iniciais do processo de aquisição de língua materna, privilegiando relações de dependências não-adjacentes (DNA) e explora a relação entre itens funcionais e marcadores de palavras de Nome (word markers). Diferentemente de trabalhos anteriores, que usaram línguas totalmente artificiais – cujas propriedades fonológicas, morfológicas e prosódicas eram muito simples –, esta pesquisa usa uma língua pseudonatural, preservando tais propriedades. A conciliação entre um modelo de processamento voltado para a aquisição da linguagem (Bootstrapping Fonológico: Morgan & Demuth, 1996; Christophe et al., 1997) e um modelo de língua que considere níveis de interface entre o sistema linguístico e outros sistemas – perceptuais e cognitivos (Programa Minimalista: Chomsky 1995; 1999 e obras posteriores) - permite compreender a passagem de um nível de representação fonético/fonológico para um nível de representação formal. Assumindo-se ainda que mecanismos estatísticos e de abstração e generalização são recursos precocemente disponíveis e explorados por bebês no processo de categorização de elementos lexicais (Marcus et al., 1999; Gómez, 2002; Newport & Aslin, 2004), a conciliação entre o modelo de língua e o modelo de processamento pretende explicitar o modo como a criança extrai do continuum sonoro, além de pistas distribucionais e prosódicas, propriedades dos traços formais dos elementos funcionais nos quais o Sistema Computacional age resultando na derivação linguística. Bebês, com média de idade de 11 meses, foram expostos durante um curto período de tempo a uma língua diferente de sua língua materna e, posteriormente, expostos a novos DPs congruentes ou não aos apresentados anteriormente. Os resultados indicam que os bebês reagiram à diferença de padrões de DNA em função daqueles previamente apresentados, escutando por mais tempo padrões não familiarizados, sugerindo que a partir de uma curta exposição a uma língua pseudonatural – diferente do padrão do PB – bebês, aos 11 meses, são capazes de abstrair e generalizar o padrão dessa “língua”. Tais resultados sugerem que mecanismos de abstração e generalização podem ser recursos utilizados por crianças no processo inicial de aquisição lexical. / This study investigates the capacities of abstraction and generalization of linguistic patterns in the early stages of the acquisition of mother tongue, emphasizing the relationship of nonadjacent dependencies (DNA) and exploring the relationship between functional items and word markers of nouns. Unlike previous studies, which used artificial languages - whose phonological, morphological and prosodical properties were very simple - this research uses a pseudonatural language, preserving such properties. The conciliation between a psycholinguistic model aimed at the acquisition of language (Phonological Bootstrapping: Morgan & Demuth, 1996; Christophe et al., 1997) and a linguistic theory based on interface levels (Minimalist Program, Chomsky, 1995; 1999) allows us to understand the passage from one level of phonetic/phonological representation to a level of formal representation. Assuming also that statistical mechanisms of abstraction and generalization are resources available to infants and exploited early by them in the process of categorization of lexical (Marcus et al., 1999; Gómez, 2002; Newport & Aslin, 2004), the conciliation between the two theories aims to clarify how the child extracts from the sonorous continuum as well as distributional and prosodic clues, properties of the formal traces of the functional elements in which the Computational System acts resulting linguistic derivations. Babies at 11 months were exposed for a short period of time to a language other than their mother tongue and later exposed to new DPs congruent or not to those previously presented. The results indicate that babies reacted to different patterns of DNA according to those previously presented, listening longer to unfamiliar patterns, suggesting that from a short exposure to a pseudonatural language, babies at 11 months are able to abstract and generalize the pattern of this language. These results suggest that mechanisms of abstraction and generalization can be used by children in the initial process of language acquisition.

Context: Distributed software development has become a most desired way of software development. Application of agile development methodologies in distributed environments has taken a new trend in developing software due to its benefits of improved communication and collaboration. Teamwork is an important concept that agile methodologies facilitate and is one of the potential determinants of team performance which was not focused in distributed agile software development. Objectives: This research shed a light on the topic of teamwork in the context of distributed agile software development. The objectives are to identify the factors contributing teamwork of distributed agile teams along with the dependencies between the factors. And, as it is not without challenges to work with unity in a heterogeneous environment, identification of challenges related to teamwork factors of distributed agile teams along with the mitigation strategies is an another objective. Methods: A systematic literature review (SLR) was employed to identify the teamwork factors along with their dependencies and corresponding challenges and mitigation strategies of each teamwork factor from state-of-the-art literature. Quasi-gold standard method was employed as search strategy in SLR to find out the primary studies representing the objective under investigation. Further a survey was conducted with industrial practitioners working in distributed agile projects to validate the findings from state-of-the-art literature. Results: A total of 13 teamwork factors (i.e. team orientation, shared leadership, mutual performance monitoring, backup behavior, feedback, team autonomy, team learning, coordination, communication, trust, collective culture, ease of use of technology, team familiarity), a set of nine dependencies between the teamwork factors and 45 challenges and 41 mitigation strategies related to the teamwork factors were identified from state-of-the-art literature. From survey result, communication, coordination, trust and team orientation were identified as four most important teamwork factors for distributed agile teams. Out of nine dependencies, seven were supported and two were not supported by the practitioners of distributed agile projects. Additionally, nine challenges and 12 mitigation strategies were identified through survey. Conclusions: From this study, we conclude that communication is the top most important factor for successful teamwork of distributed agile teams. And, unlike its prime importance in distributed software development for getting teams work together, trust was identified with a third priority for successful teamwork of distributed agile teams. Similar to the findings of the agile teams, team autonomy was identified with least importance towards the successful teamwork of distributed agile teams. Results of dependencies show that there is need for future research to explore all the dependencies between the teamwork factors. Furthermore, there are teamwork factors with no challenges and mitigation strategies being identified in state-of-the-art literature but later, through survey it was found that practitioners are facing the challenges for that particular teamwork factor. Though, this study identified those missed challenges, due to the limited number of participants involved in the survey, we cannot conclude that these were the only challenges faced in relation to the teamwork. Hence, there is a need to have a dedicated investigation in exploring all the challenges and mitigation strategies, such that it would help the distributed agile teams in attaining the fruitful interactions between them. / H.no. 5-5-289, Prashanth Nagar, Vanasthalipuram, Hyderabad-500070, Andhra Pradesh. India

Companies that operate with critical infrastructure face a growing threat from cyber-attacks while at the same time the development in the business is rapidly moving towards a higher level of digitalization. A common type of system in critical infrastructure is supervisory control and data acquisition systems, these systems have properties that can affect their security and will therefore serve as the basis for this thesis work. To stay protected despite systems changes, companies need to make risk assessments in order to analyze how changes will affect the overall system. One thing that is important to focus on is dependencies within the system, this means that not only interaction among computers and networks are concerned but instead a more holistic view of the system need to be considered. This thesis aims to aid the process of a future risk assessment by providing a methodology to be used as a preparatory step before a risk assessment by describing the current situation of the system. This is done by evaluating two system modeling approaches, and also by proposing a number of perspectives that each provides different kind of information about the system’s dependencies. These perspectives are then evaluated by creating system models and dependency graphs, and discussing the outcomes with experts in a utility company to find out their applicability. According to the experts, the proposed perspectives have promising properties that can be useful in future risk assessments as well as in other scenarios. Moreover, the evaluated modeling approaches got positive comments during evaluation and are considered to serve their purpose.

The thesis aims to investigate some of the approaches to modelling portfolio returns with heavy-tailed risk factors. It first elaborates on the univariate time series models, and compares the benchmark model (GARCH with Student t innovations or its GJR extension) predictive performance with its two competitors, the EVT-GARCH model and the Markov-Switching Multifractal (MSM) model. The motivation of EVT extension of GARCH specification is to use a more proper distribution of the innovations, based on the empirical distribution function. The MSM is one of the best performing models in the multifractal literature, a markov-switching model which is unique by its parsimonious specification and variability. The performance of these models is assessed with Mincer-Zarnowitz regressions as well as by comparison of quality of VaR and expected shortfall predictions, and the empirical analysis shows that for the risk management purposes the EVT-GARCH dominates the benchmark as well as the MSM. The second part addresses the dependence structure modelling, using the Gauss and t-copula to model the portfolio returns and compares the result with the classic variance-covariance approach, concluding that copulas offer a more realistic estimates of future extreme quantiles.

Natural language is inherently ambiguous. For example, the word "bank" can mean a financial institution or a river shore. Finding the correct meaning of a word in a particular context is a task known as word sense disambiguation (WSD), which is essential for many natural language processing applications such as machine translation, information retrieval, and others. While most current WSD methods try to disambiguate a small number of words for which enough annotated examples are available, the method proposed in this thesis attempts to address all words in unrestricted text. The method is based on constraints imposed by syntactic dependencies and concept generalizations drawn from an external dictionary. The method was tested on standard benchmarks as used during the SENSEVAL-2 and SENSEVAL-3 WSD international evaluation exercises, and was found to be competitive.

Opinion Target Extraction (OTE) is a well-established subtask of sentiment analysis. While detecting sentiment polarity is useful in itself, the ability to extract the targets of the opinions allows for more thorough decision making. For example, an owner of a restaurant needs to know whether the guests are complaining about the food, or the ambience, or any other aspect of their establishment, etc. Despite the lexical information being crucial for the task, syntactic structures have potential in being used to correctly decide among multiple candidate entities. Rules based on such structures have been used previously for the task. The objective of this thesis is to investigate, whether syntactic information influences the behavior of the state-of-the-art models such as recurrent neural networks for the OTE task. We did not find any substantial evidence to suggest that adding the syntactic information influences the behavior of the models.

Many organizations turn to agile methods and practices in their organization in order to retain competitiveness in today's rapidly changing environment and changing customer demands. Researchers claim agile practices, such as Agile Project Management to be most successful if implemented in the entire organization, in an all-or-nothing approach. However, as many traditional organizations are attempting to adopt agile principles such as APM, few studies have been made to what extent agile methods and practices can be successful in traditional organizations. This research investigates how a APM-team at SEB can function in accordance to agile philosophy, and further, if the legacy and traditional structures at SEB counteract the APM-team. The study is a single case study, investigating one APM-team at SEB through semi-structured interviews and organizational documents. In order to answer the research question, a model of analysis was derived in order to capture the important theoretical concepts. It was found that the investigated APM-team in SEB does not function fully in order with agile philosophies, and further that the traditional structures and legacy at SEB hinders the APMteam to work according to agile philosophies. It was also found that the APM-team experienced difficulties with the actual agile way of working, which could affect their ability to work in accordance with said practices. Further research is needed for a greater context to fully understand how traditional organizations can counteract agile initiatives.