In this thesis, we address several generic problems concerned with procurement of tasks from a crowd that consists of strategic workers with uncertainty in their qualities. These problems assume importance as the quality of services in a service marketplace is known to degrade when there is (unchecked) information asymmetry pertaining to quality. Moreover, crowdsourcing is increasingly being used for a wide variety of tasks these days since it offers high levels of flexibility to workers as well as employers. We seek to address the issue of quality uncertainty in crowdsourcing through mechanism design and machine learning. As the interactions in web-based crowdsourcing platform are logged, the data captured could be used to learn unknown parameters such as qualities of individual crowd workers. Further, many of these platforms invite bids by crowd workers for available tasks but the strategic workers may not bid truthfully. This warrants the use of mechanism design to induce truthful bidding. There ensues a complex interplay between machine learning and mechanism design, leading to interesting technical challenges. We resolve some generic challenges in the context of the following problems. Design of a quality eliciting mechanism with interdependent values We consider an expert sourcing problem, where a planner seeks opinions from a pool of experts. Execution of the task at an assured quality level in a cost effective manner turns out to be a mechanism design problem when the individual qualities are private information of the experts. Also, the task execution problem involves interdependent values, where truthfulness and efficiency cannot be achieved in an unrestricted setting due to an impossibility result. We propose a novel mechanism that exploits the special structure of the problem and guarantees allocative efficiency, ex-post incentive compatibility and strict budget balance for the mechanism, and ex-post individual rationality for the experts. Design of an optimal dimensional crowdsourcing auction We study the problem faced by an auctioneer who gains stochastic rewards by procuring multiple units of a service from a pool of heterogeneous strategic workers. The reward obtained depends on the inherent quality of the worker; the worker’s quality is fixed but unknown. The costs and capacities are private information of the workers. The auctioneer is required to elicit costs and capacities (making the mechanism design dimensional) and further, has to learn the qualities of the workers as well, to enable utility maximization. To solve this problem, we design a dimensional multi-armed bandit auction that maximizes the expected utility of the auctioneer subject to incentive compatibility and individual rationality while simultaneously learning the unknown qualities of the agents. Design of a multi-parameter learning mechanism for crowdsourcing We investigate the problem of allocating divisible jobs, arriving online, to workers in a crowd-sourcing platform. Each job is split into a certain number of tasks that are then allocated to workers. These tasks have to meet several constraints that depend on the worker performance. The performance of each worker in turn is characterized by several intrinsic stochastic parameters. In particular, we study a problem where each arriving job has to be completed within a deadline and each task has to be completed, honouring a lower bound on quality. The job completion time and quality of each worker are stochastic with fixed but unknown means. We propose a learning mechanism to elicit the costs truthfully while simultaneously learning the stochastic parameters. Our proposed mechanism is dominant strategy incentive compatible and ex-post individually rational with asymptotically optimal regret performance.

The World Wide Web is an infrastructure to publish and retrieve information through web resources. It evolved from a static Web 1.0 to a multimodal and interactive communication and information space which is used to collaboratively contribute and discuss web resources, which is better known as Web 2.0. The evolution into a Semantic Web (Web 3.0) proceeds. One of its remarkable advantages is the decentralized and interlinked data composition. Hence, in contrast to its data distribution, workflows and technologies for decentralized collaborative contribution are missing. In this paper we propose the Structured Feedback protocol as an interactive addition to the Web of Data. It offers support for users to contribute to the evolution of web resources, by providing structured data artifacts as patches for web resources, as well as simple plain text comments. Based on this approach it enables crowd-supported quality assessment and web data cleansing processes in an ad-hoc fashion most web users are familiar with.

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This thesis explores the visual perception of material change over time, a novel topic that has received little attention so far. We aimed to understand the material surface features and mental representations associated with material change over time by the human visual system, and possibly wider cognitive systems. To this end, we performed a series of experiments with varying methodologies. These included a psychophysics experiment, online experiments, and data collection during a science festival. The latter showed that the general public mentioned “Faded (colour)” most often to describe material change over time and that specific material surface change features clustered around specific materials. In another experiment, material type, but not colour or the geometrical distribution, had a significant effect on perceived material change. Other experiments partially contradicted this finding. It was found that perceived material type showed a significant, non-linear association with perceived material change, replicating earlier findings on the effect of material type. In contrast, material surface lightness, a constituent of colour, was associated with perceived material change. The same held for components of the geometrical distribution. They showed a minor contribution to the perception of material change, but a major one to perceived material type. Together, our findings suggest that the human visual system seems to use constituents of material surface colour as a cue to material change over time. The geometrical distribution seems to play a minor role. Although these contributions may vary with material type, as our findings showed that material type affected the perception of material change over time. / DyViTo (Dynamics in Vision and Touch) has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 765121

Map Kibera project and it’s Voice of Kibera reporting initiative present an example of new media applying the principle of crowd sourcing to foster social change and provide voice to community of Kibera, Kenya. The aim of this study was to analyses, firstly, how the concept of participatory communication has been applied during the implementation of the project. As a basis for this approach an Integrated Model of Communication for Social Change was applied during the analysis of articles being produced on two project blogs to identify what steps have been implemented and what new aspects could be brought. Secondly, it was important to understand what social change the implementation of such project could bring to community it serves for. Finally, in order to develop a strategy for sustainability possible barriers/limitations of citizen/actor engagement were identified. Research tools used for this analysis were qualitative semi-structured interviews with project team members as well as participants/non participants of the project combined together with quantitative content analysis applied on articles produced on Map Kibera and Voice of Kibera blogs.Most important findings indicate that the application of IMCFSC took place almost fully but was applied on a particular community – project team. At the same time the use of crowd sourcing platform and reporting gave citizens of Kibera an opportunity to create their own agenda and provide a real picture of the area thus gaining a “voice” and possibility to speak out loud to broader communities. Nevertheless it is important to mention that the access to information created during the project was possible mostly in the offline form (printed materials, maps) and via mobile phones thus indicating to such barriers as the lack of such ICT tools as computers and also to the need to co-operate more closely to broader community of Kibera to avoid possible misconception of the work of the project. These findings are important to consider when planning implementation of similar projects in other communities located in different geographical, political and social settings.

La notion de trajectoire fait l'objet de nombreux travaux en informatique. La trajectoire de vie a plusieurs particularités qui la distinguent des trajectoires habituellement considérées dans ces travaux. C'est d'abord son emprise temporelle, qui est celle de la vie, de l'existence du sujet observé. C'est ensuite son emprise thématique, celle-ci pouvant potentiellement concerner de multiples aspects de la vie d'un objet ou d'un individu. C'est enfin, l'utilisation métaphorique du terme de trajectoire, qui renvoie davantage au sens de la trajectoire qu'à la description d'une simple évolution dans le temps et l'espace. La trajectoire de vie est utilisée par l'expert (sociologue, urbaniste...) qui souhaite mettre en perspective dans le temps les informations sur les individus pour mieux les comprendre. Les motivations d'étude de la trajectoire de vie sont différentes selon les cas d'application et les thématiques considérées : le rapport au travail, la vie familiale, la vie sociale, la santé, la trajectoire résidentielle...Nous proposons une approche d'étude des trajectoires de vie, basée sur le Web Sémantique, qui en permet la modélisation, la collecte et l'analyse. Cette approche est concrétisée par une architecture logicielle. Cette architecture repose sur un patron de conception d'ontologie de trajectoire de vie, ainsi que sur un modèle de facteurs explicatifs d'évènements de vie. Pour la modélisation,nous avons conçu des algorithmes qui permettent la création d'une ontologie de trajectoire de vie en exploitant le patron et le modèle précédents. Pour lacollecte de données, nous avons développé des APIs permettant de faciliter i)la construction d'une interface de collecte de données conforme aux modéles ;ii) l'insertion des données collectées dans un Triple Store. Notre approche permet la représentation, et, par suite, la collecte et l'exploitation d'informations multi-granulaires, qu'elles soient spatiales, temporelles ou thématiques.Enfin, pour permettre l'analyse des trajectoires, nous proposons des fonctions génériques, implémentées en étendant le langage SPARQL. L'approche méthodologique et les outils proposés sont validés sur un cas d'application visant à étudier les choix résidentiels d'individus en mettant en exergue les caractéristiques de leur trajectoire résidentielle et les éléments explicatifs de celle-ci. / The notion of trajectory is the subject of many works in computer science. The life trajectory has several peculiarities which distinguish it from the trajectories usually considered in these works. It is first of all its temporal hold, which is the life, the existence of the observed subject. It is then its thematic hold, this one potentially concerning multiple aspects of the life of an object or an individual. Finally, it is the metaphorical use of the term trajectory, which refers more to the meaning of the trajectory than to the description of a simple evolution in time and space. The life trajectory is used by the expert (sociologist, urban planner ...) who wishes to put in perspective the information on individuals to better understand their choices. The motivations for studying the life trajectory are depending on the application and themes considered: the relation to work and employment, family life, social life, health, residential trajectory ...We propose a Semantic Web based approach to study life trajectories, which allows their modeling, collection and analysis. This approach is embodied by a software architecture whose components are configurable for each application case. This architecture is based on a life trajectory ontology design pattern, as well as a model of explanatory factors for life events. To operationalize the proposed modeling, we designed algorithms that allow the creation of a life trajectory ontology by exploiting the previous pattern and model. For data collection, we developed APIs to facilitate i) the construction of a model-compliant data collection interface; and ii) the insertion of the collected data into a Triple Store. Our approach allows the representation, and hence the collection and exploitation of multi-granular information, whether spatial, temporal or thematic. Finally, to allow the analysis of the trajectories, we propose generic functions, which are implemented by extending the SPARQL language.The methodological approach and the proposed tools are validated on a case study on residential choices of individuals in the Grenoble metropolitan area by highlighting the characteristics of their residential trajectory and the explanatory elements of it, including from their personal and professional trajectories.

This study attempts to shed light on the efficacy of crowdsourcing as a means of translating web content in Canada. Within, we seek to explore and understand if a model can be created that can estimate the effectiveness of crowdsourced translation as a means of bridging the Canadian Linguistic Digital Divide. To test our hypotheses and models, we use structural equation modeling techniques coupled with confidence intervals for comparing experimental crowdsourced translation to both professional and machine translation baselines. Furthermore, we explore a variety of factors which influence the quality of the experimental translations, how those translations performed in the context of their source text, and the ways in which the views of the quality of the experimental translations were measured before and after participants were made aware of how the experimental translations were created.

Am Ende der Dresden Summer School 2012 haben die Teilnehmerinnen und Teilnehmer eigene Ideen und Impulse zur Zukunft der Vernetzung von Kultur- und Wissenschaftseinrichtungen vorgestellt. Claudia Becker, wissenschaftliche Mitarbeiterin am Vilém Flusser Archiv der Universität der Künste Berlin, ist an neuen Wegen der Wissens- und Kulturvermittlung mit digitalen Technologien interessiert. Wissen, Wissenssammlungen und Wissensordnungen haben sich im Laufe der Jahre verändert, ebenso wie die Wissensproduktion, die Schaffung neuen Wissens, die Wissenschaft selbst. Der Baum des Wissens, „arbor porphyriana“ oder auch „arbor scientiae“ war seit der Antike eine gültige Metapher und das Klassifikationsschema für die Struktur des Wissen, die epistemologische Ordnung. So lehnte auch Denis Diderot die Ordnung seiner berühmten Enzyklopädie an die Baumstruktur des Wissens von Francis Bacon an. Wohl wissend, dass Wissen Macht ist, widmeten Diderot und seine Enzyklopädisten einen großen Teil ihrer Lebenszeit, um das Wissen aus allen Bereichen der Welt zu sammeln und aller Welt zugänglich zu machen. Diderot nutzte somit damals schon die Intelligenz des Schwarmes, seine Enzyklopädie ist ein Produkt des „Crowd Sourcing“, eines kollektiven Verbundes mehrerer Autoren, die gemeinsam an einem Werk schreiben, um Wissen im Namen der Aufklärung den Herrschenden zu entreißen und möglichst vielen zugänglich zu machen. Die Parallelen zu einem der heutigen größten und bedeutendsten Wissensprojekte – der Internet-Enzyklopädie Wikipedia – sind unverkennbar. [...]

This study attempts to shed light on the efficacy of crowdsourcing as a means of translating web content in Canada. Within, we seek to explore and understand if a model can be created that can estimate the effectiveness of crowdsourced translation as a means of bridging the Canadian Linguistic Digital Divide. To test our hypotheses and models, we use structural equation modeling techniques coupled with confidence intervals for comparing experimental crowdsourced translation to both professional and machine translation baselines. Furthermore, we explore a variety of factors which influence the quality of the experimental translations, how those translations performed in the context of their source text, and the ways in which the views of the quality of the experimental translations were measured before and after participants were made aware of how the experimental translations were created.

This study attempts to shed light on the efficacy of crowdsourcing as a means of translating web content in Canada. Within, we seek to explore and understand if a model can be created that can estimate the effectiveness of crowdsourced translation as a means of bridging the Canadian Linguistic Digital Divide. To test our hypotheses and models, we use structural equation modeling techniques coupled with confidence intervals for comparing experimental crowdsourced translation to both professional and machine translation baselines. Furthermore, we explore a variety of factors which influence the quality of the experimental translations, how those translations performed in the context of their source text, and the ways in which the views of the quality of the experimental translations were measured before and after participants were made aware of how the experimental translations were created.