Semantic Query Reformulation in Social PDMS

We consider social peer-to-peer data management systems (PDMS), where each peer maintains both semantic mappings between its schema and some acquaintances, and social links with peer friends. In this context, reformulating a query from a peer's schema into other peer's schemas is a hard problem, as it may generate as many rewritings as the set of mappings from that peer to the outside and transitively on, by eventually traversing the entire network. However, not all the obtained rewritings are relevant to a given query. In this paper, we address this problem by inspecting semantic mappings and social links to find only relevant rewritings. We propose a new notion of 'relevance' of a query with respect to a mapping, and, based on this notion, a new semantic query reformulation approach for social PDMS, which achieves great accuracy and flexibility. To find rapidly the most interesting mappings, we combine several techniques: (i) social links are expressed as FOAF (Friend of a Friend) links to characterize peer's friendship and compact mapping summaries are used to obtain mapping descriptions; (ii) local semantic views are special views that contain information about external mappings; and (iii) gossiping techniques improve the search of relevant mappings. Our experimental evaluation, based on a prototype on top of PeerSim and a simulated network demonstrate that our solution yields greater recall, compared to traditional query translation approaches proposed in the literature.Comment: 29 pages, 8 figures, query rewriting in PDM

Improving User Interaction on Ontology-based Peer Data Management Systems

The issue of user interaction for query formulation and execution has been investigated for distributed and dynamic environments, such as Peer Data Management System (PDMS). Many of these PDMS are semantic based and composed by data peers which export schemas that are represented by ontologies. In the literature we can find some proposed PDMS interfaces, but none of them addresses, in a general way, the needs of a PDMS for user interaction. In this work we propose a visual user query interface for ontology-based PDMS. It provides a simple and straightforward interaction with this type of system. It aims not only providing a natural visual query interface but also supporting a precise and direct manipulation of the data schemas for query generation

Viewpoints on emergent semantics

Authors include:Philippe Cudr´e-Mauroux, and Karl Aberer (editors), Alia I. Abdelmoty, Tiziana Catarci, Ernesto Damiani, Arantxa Illaramendi, Robert Meersman, Erich J. Neuhold, Christine Parent, Kai-Uwe Sattler, Monica Scannapieco, Stefano Spaccapietra, Peter Spyns, and Guy De Tr´eWe introduce a novel view on how to deal with the problems of semantic interoperability in distributed systems. This view is based on the concept of emergent semantics, which sees both the representation of semantics and the discovery of the proper interpretation of symbols as the result of a self-organizing process performed by distributed agents exchanging symbols and having utilities dependent on the proper interpretation of the symbols. This is a complex systems perspective on the problem of dealing with semantics. We highlight some of the distinctive features of our vision and point out preliminary examples of its applicatio

Processing Rank-Aware Queries in Schema-Based P2P Systems

Effiziente Anfragebearbeitung in Datenintegrationssystemen sowie in P2P-Systemen ist bereits seit einigen Jahren ein Aspekt aktueller Forschung. Konventionelle Datenintegrationssysteme bestehen aus mehreren Datenquellen mit ggf. unterschiedlichen Schemata, sind hierarchisch aufgebaut und besitzen eine zentrale Komponente: den Mediator, der ein globales Schema verwaltet. Anfragen an das System werden auf diesem globalen Schema formuliert und vom Mediator bearbeitet, indem relevante Daten von den Datenquellen transparent für den Benutzer angefragt werden. Aufbauend auf diesen Systemen entstanden schließlich Peer-Daten-Management-Systeme (PDMSs) bzw. schemabasierte P2P-Systeme. An einem PDMS teilnehmende Knoten (Peers) können einerseits als Mediatoren agieren andererseits jedoch ebenso als Datenquellen. Darüber hinaus sind diese Peers autonom und können das Netzwerk jederzeit verlassen bzw. betreten. Die potentiell riesige Datenmenge, die in einem derartigen Netzwerk verfügbar ist, führt zudem in der Regel zu sehr großen Anfrageergebnissen, die nur schwer zu bewältigen sind. Daher ist das Bestimmen einer vollständigen Ergebnismenge in vielen Fällen äußerst aufwändig oder sogar unmöglich. In diesen Fällen bietet sich die Anwendung von Top-N- und Skyline-Operatoren, ggf. in Verbindung mit Approximationstechniken, an, da diese Operatoren lediglich diejenigen Datensätze als Ergebnis ausgeben, die aufgrund nutzerdefinierter Ranking-Funktionen am relevantesten für den Benutzer sind. Da durch die Anwendung dieser Operatoren zumeist nur ein kleiner Teil des Ergebnisses tatsächlich dem Benutzer ausgegeben wird, muss nicht zwangsläufig die vollständige Ergebnismenge berechnet werden sondern nur der Teil, der tatsächlich relevant für das Endergebnis ist. Die Frage ist nun, wie man derartige Anfragen durch die Ausnutzung dieser Erkenntnis effizient in PDMSs bearbeiten kann. Die Beantwortung dieser Frage ist das Hauptanliegen dieser Dissertation. Zur Lösung dieser Problemstellung stellen wir effiziente Anfragebearbeitungsstrategien in PDMSs vor, die die charakteristischen Eigenschaften ranking-basierter Operatoren sowie Approximationstechniken ausnutzen. Peers werden dabei sowohl auf Schema- als auch auf Datenebene hinsichtlich der Relevanz ihrer Daten geprüft und dementsprechend in die Anfragebearbeitung einbezogen oder ausgeschlossen. Durch die Heterogenität der Peers werden Techniken zum Umschreiben einer Anfrage von einem Schema in ein anderes nötig. Da existierende Techniken zum Umschreiben von Anfragen zumeist nur konjunktive Anfragen betrachten, stellen wir eine Erweiterung dieser Techniken vor, die Anfragen mit ranking-basierten Anfrageoperatoren berücksichtigt. Da PDMSs dynamische Systeme sind und teilnehmende Peers jederzeit ihre Daten ändern können, betrachten wir in dieser Dissertation nicht nur wie Routing-Indexe verwendet werden, um die Relevanz eines Peers auf Datenebene zu bestimmen, sondern auch wie sie gepflegt werden können. Schließlich stellen wir SmurfPDMS (SiMUlating enviRonment For Peer Data Management Systems) vor, ein System, welches im Rahmen dieser Dissertation entwickelt wurde und alle vorgestellten Techniken implementiert.In recent years, there has been considerable research with respect to query processing in data integration and P2P systems. Conventional data integration systems consist of multiple sources with possibly different schemas, adhere to a hierarchical structure, and have a central component (mediator) that manages a global schema. Queries are formulated against this global schema and the mediator processes them by retrieving relevant data from the sources transparently to the user. Arising from these systems, eventually Peer Data Management Systems (PDMSs), or schema-based P2P systems respectively, have attracted attention. Peers participating in a PDMS can act both as a mediator and as a data source, are autonomous, and might leave or join the network at will. Due to these reasons peers often hold incomplete or erroneous data sets and mappings. The possibly huge amount of data available in such a network often results in large query result sets that are hard to manage. Due to these reasons, retrieving the complete result set is in most cases difficult or even impossible. Applying rank-aware query operators such as top-N and skyline, possibly in conjunction with approximation techniques, is a remedy to these problems as these operators select only those result records that are most relevant to the user. Being aware that in most cases only a small fraction of the complete result set is actually output to the user, retrieving the complete set before evaluating such operators is obviously inefficient. Therefore, the questions we want to answer in this dissertation are how to compute such queries in PDMSs and how to do that efficiently. We propose strategies for efficient query processing in PDMSs that exploit the characteristics of rank-aware queries and optionally apply approximation techniques. A peer's relevance is determined on two levels: on schema-level and on data-level. According to its relevance a peer is either considered for query processing or not. Because of heterogeneity queries need to be rewritten, enabling cooperation between peers that use different schemas. As existing query rewriting techniques mostly consider conjunctive queries only, we present an extension that allows for rewriting queries involving rank-aware query operators. As PDMSs are dynamic systems and peers might update their local data, this dissertation addresses not only the problem of considering such structures within a query processing strategy but also the problem of keeping them up-to-date. Finally, we provide a system-level evaluation by presenting SmurfPDMS (SiMUlating enviRonment For Peer Data Management Systems) -- a system created in the context of this dissertation implementing all presented techniques

Designing Cross-Company Business Intelligence Networks

Business Intelligence (BI) ist der allgemein akzeptierte Begriff für Methoden, Konzepte und Werkzeuge zur Sammlung, Aufbereitung, Speicherung, Verteilung und Analyse von Daten für Management- und Geschäftsentscheidungen. Obwohl unternehmensübergreifende Kooperation in den vergangenen Jahrzehnten stets an Einfluss gewonnen hat, existieren nur wenige Forschungsergebnisse im Bereich unternehmensübergreifender BI. Die vorliegende Arbeit stellt eine Arbeitsdefinition des Begriffs Cross-Company BI (CCBI) vor und grenzt diesen von gemeinschaftlicher Entscheidungsfindung ab. Auf Basis eines Referenzmodells, das existierende Arbeiten und Ansätze verwandter Forschungsbereiche berücksichtigt, werden umfangreiche Simulationen und Parametertests unternehmensübergreifender BI-Netzwerke durchgeführt. Es wird gezeigt, dass eine Peer-To-Peer-basierte Gestaltung der Netzwerke leistungsfähig und kompetitiv zu existierenden zentral-fokussierten Ansätzen ist. Zur Quantifizierung der Beobachtungen werden Messgrößen geprüft, die sich aus existierenden Konzepten zur Schemaüberführung multidimensionaler Daten sowie Überlegungen zur Daten- und Informationsqualität ableiten oder entwickeln lassen.Business Intelligence (BI) is a well-established term for methods, concepts and tools to retrieve, store, deliver and analyze data for management and business purposes. Although collaboration across company borders has substantially increased over the past decades, little research has been conducted specifically on Cross-Company BI (CCBI). In this thesis, a working definition and distinction from general collaborative decision making is proposed. Based on a reference model that takes existing research and related approaches of adjacent fields into account a peer-to-peer network design is created. With an extensive simulation and parameter testing it is shown that the design proves valuable and competitive to centralized approaches and that obtaining a critical mass of participants leads to improved usefulness of the network. To quantify the observations, appropriate quality measures rigorously derived from respected concepts on data and information quality and multidimensional data models are introduced and validated

Development strategies of re-urbanization for sustainable extensive towns

Tese de Doutoramento em Arquitetura, com a especialização em Desenho e Computação apresentada na Faculdade de Arquitetura da Universidade de Lisboa para obtenção do grau de Doutor.O território português apresenta uma dispersão urbana generalizada que incentiva práticas de consumo do solo, causa altos custos infraestruturais e coloca novos problemas nas políticas urbanas e regionais. O tema da presente pesquisa é a mitigação dos efeitos negativos da urbanização extensiva do território português, propondo ferramentas para processos de reurbanização / intensificação para tais territórios dispersos. A esse respeito, este trabalho traz uma nova contribuição ao processo de conceição e implementação de planos de desenvolvimento territorial capazes de incorporar estratégias de desenvolvimento sustentável para diferentes tipos de territórios dispersos, integrando as ferramentas tradicionais de planeamento em uso em contextos de planeamento local. Para isso, o presente trabalho desenvolveu uma ferramenta metodológica que reúne análises de rede, ferramentas de estudo de densidade / dispersão e análises de capital territorial e que constitui um sistema válido de apoio à tomada de decisão capaz de ajudar planeadores e stakeholders a abordar questões econômicas, desafios sociais e de governança colocados pelos territórios dispersos. Para isso, foi desenvolvido um conjunto de métodos quantitativos para avaliar o capital territorial de diferentes territórios (compactos e dispersos) identificando a suas características, vocações e potenciais no que respeita ao desenvolvimento territórial, medindo e monitorando as suas flutuações em uma lista selecionada de indicadores territoriais afetada pela introdução de diferentes cenários de desenvolvimento. Ao analisar o território de uma perspectiva configuracional e econômico-espacial, e não apenas de uma perspectiva morfológica, a presente investigação tenta trazer uma contribuição original ao processo de elaboração de um novo framework operacional capaz de lidar com os territórios dispersos, com o intuito de constituir um instrumento de surporte para planeadores e administrações publicas no âmbito da tomada de decisões informadas sobre vários tópicos, do planejamento à governança. Um case study, o concelho de Sintra, altamente representativo da questão atual da dispersão territorial em Portugal, foi analisado e discutido. O desenvolvimento de um novo framework para a avaliação de diferentes cenários de desenvolvimento, que incorpora o conceito de capital territorial, guia na busca de estratégias e ferramentas para reurbanização estratégica ou desenvolvimento setorial desconcentrado do território em análise, produzindo, esperançosamente, ambientes urbanos mais sustentáveis com mais potencial para uma interação humana vital, ou seja, uma melhor “urbanidade”.ABSTRACT:The Portuguese territory displays a wide-spread urban dispersion that encouraged land-consuming practices, causes high infrastructural costs and poses new issues to urban and regional policies. The subject of the present research is the mitigation of the negative effects of extensive urbanization of the Portuguese territory focusing on processes of re-urbanization / intensification for such dispersed territories. In this respect, this work brings a novel contribution to the process of concealing and implementing territorial development plans capable of incorporating sustainable development strategies for different kinds of dispersed territories, integrating the traditional planning tool in use in local planning. In order to do so, the present work developed a methodological tool – bringing together network analyses, density/dispersion assessment tools and a territorial capital analyses – that constitutes a valid decision-making support system capable of helping planners and stakeholders to address the economic, social and governance challenges posed by dispersed territories. In order to do so a set of quantitative methods was developed to assess the territorial capital of different territories (both compact and dispersed) to identify their inherent characteristics, vocations and potentials for development, measuring and monitoring the fluctuations in a selected list of territorial indicators as affected by the introduction of different development scenarios. By analyzing the territory from a configurational and spatial-economic perspective rather than just from a morphological perspective, the present research tries to bring an original contribution to the process of crafting a new operative framework capable of dealing with the dispersed territories assisting planners and administrations to take informed decision on various topics, from planning to governance. A case study, the municipality of Sintra, highly representative of the current issue of the territorial dispersion in Portugal, has been analyzed and discussed. The development of a novel framework for the assessment of different development scenarios that will incorporate the concept of territorial capital will guide in finding strategies and tools for strategic re-urbanization or deconcentrated sectorial development of the territory in analysis, hopefully producing more sustainable urban environments with potential for vital human interaction, i.e. a better “urbanity”.N/

Acquiring syntactic and semantic transformations in question answering

One and the same fact in natural language can be expressed in many different ways by using different words and/or a different syntax. This phenomenon, commonly called paraphrasing, is the main reason why Natural Language Processing (NLP) is such a challenging task. This becomes especially obvious in Question Answering (QA) where the task is to automatically answer a question posed in natural language, usually in a text collection also consisting of natural language texts. It cannot be assumed that an answer sentence to a question uses the same words as the question and that these words are combined in the same way by using the same syntactic rules. In this thesis we describe methods that can help to address this problem. Firstly we explore how lexical resources, i.e. FrameNet, PropBank and VerbNet can be used to recognize a wide range of syntactic realizations that an answer sentence to a given question can have. We find that our methods based on these resources work well for web-based Question Answering. However we identify two problems: 1) All three resources as of yet have significant coverage issues. 2) These resources are not suitable to identify answer sentences that show some form of indirect evidence. While the first problem hinders performance currently, it is not a theoretical problem that renders the approach unsuitable–it rather shows that more efforts have to be made to produce more complete resources. The second problem is more persistent. Many valid answer sentences–especially in small, journalistic corpora–do not provide direct evidence for a question, rather they strongly suggest an answer without logically implying it. Semantically motivated resources like FrameNet, PropBank and VerbNet can not easily be employed to recognize such forms of indirect evidence. In order to investigate ways of dealing with indirect evidence, we used Amazon’s Mechanical Turk to collect over 8,000 manually identified answer sentences from the AQUAINT corpus to the over 1,900 TREC questions from the 2002 to 2006 QA tracks. The pairs of answer sentences and their corresponding questions form the QASP corpus, which we released to the public in April 2008. In this dissertation, we use the QASP corpus to develop an approach to QA based on matching dependency relations between answer candidates and question constituents in the answer sentences. By acquiring knowledge about syntactic and semantic transformations from dependency relations in the QASP corpus, additional answer candidates can be identified that could not be linked to the question with our first approach

A schema-based peer-to-peer infrastructure for digital library networks

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International project teams as innovation hubs: power and politics in the knowledge change process

The aim of this investigation is to understand how international project teams enable mature multinational enterprises (MNEs) to cope with knowledge diversity and political activity, two well-known disruptive organizational phenomena, in order to leverage their innovative potential and competitive capabilities. To answer this question a longitudinal multi-case study has been designed to collect in-depth qualitative data from three large-scale international projects conducted by a focal MNE and an array of its subsidiaries. In a dialectic way, data collected has been used both to enhance the dynamic knowledge change framework provided by contemporary sociology and to explain the complex mechanisms that make international project teams an increasingly used organizational tool. As a result, knowledge change (and thus innovation) has been found to hinge on a dynamic balance between power and politics which is favored by conditions that are inherent to these organizational settings. Finally, a model describing the mechanisms that enable international project teams to drive knowledge diversity and political activity towards innovation and knowledge change within MNEs has been developed.L'objectiu d'aquesta investigació és entendre com els equips de projectes internacionals permeten a les empreses multinacionals madures fer front a la diversitat de coneixements i l'activitat política, dues reconegudes fonts de problemes organitzacionals, amb la finalitat de potenciar les seves capacitats d'innovació i potencial competitiu . Per respondre a aquesta pregunta un estudi longitudinal embolicant casos múltiples s'ha desenvolupat per recollir dades qualitatives en profunditat des de tres grans projectes internacionals a càrrec d'una empresa multinacional focal i una gran varietat de les seves filials. D'una manera dialèctica, les dades recollides han estat utilitzats tant per millorar el marc del canvi dinàmic del coneixement proposat per la sociologia contemporània i explicar els complexos mecanismes que fan que els equips de projectes internacionals en una eina cada vegada més utilitzada per aquestes organitzacions. Com a resultat, es mostra que el canvi d'un determinat coneixement depèn d'un equilibri dinàmic entre poder i política afavorit per les condicions que són inherents a aquests formats organitzacionals. Finalment, es desenvolupa un model que detalla els mecanismes que permeten als equips de projectes internacionals impulsar la diversitat de coneixements i l'activitat política cap a la innovació i el canvi del coneixement dins de les empreses multinacionals madures.El objetivo de esta investigación es entender cómo los equipos de proyectos internacionales permiten a las empresas multinacionales maduras hacer frente a la diversidad de conocimientos y la actividad política, dos reconocidas fuentes de problemas organizacionales, con el fin de potenciar sus capacidades de innovación y potencial competitivo. Para responder a esta pregunta un estudio longitudinal envolviendo casos múltiplos se ha desarrollado para recoger datos cualitativos en profundidad desde tres grandes proyectos internacionales a cargo de una empresa multinacional focal y una gran variedad de sus filiales. De una manera dialéctica, los datos recogidos han sido utilizados tanto para mejorar el marco del cambio dinámico del conocimiento propuesto por la sociología contemporánea y explicar los complejos mecanismos que hacen que los equipos de proyectos internacionales en una herramienta cada vez más utilizada por estas organizaciones. Como resultado, se muestra que el cambio de un determinado conocimiento depende de un equilibrio dinámico entre poder y política favorecido por las condiciones que son inherentes a estos formatos organizacionales. Por fin, se desarrolla un modelo que detalla los mecanismos que permiten a los equipos de proyectos internacionales impulsar la diversidad de conocimientos y la actividad política hacia la innovación y el cambio del conocimiento dentro de las empresas multinacionales maduras