Web Authentication Using Third Parties In Untrusted Environments

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Web Authentication Using Third Parties In Untrusted Environments

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Author : Anna Vapen
language : en
Publisher: Linköping University Electronic Press
Release Date : 2016-08-22

Web Authentication Using Third Parties In Untrusted Environments written by Anna Vapen and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-08-22 with categories.

With the increasing personalization of the Web, many websites allow users to create their own personal accounts. This has resulted in Web users often having many accounts on different websites, to which they need to authenticate in order to gain access. Unfortunately, there are several security problems connected to the use and re-use of passwords, the most prevalent authentication method currently in use, including eavesdropping and replay attacks. Several alternative methods have been proposed to address these shortcomings, including the use of hardware authentication devices. However, these more secure authentication methods are often not adapted for mobile Web users who use different devices in different places and in untrusted environments, such as public Wi-Fi networks, to access their accounts. We have designed a method for comparing, evaluating and designing authentication solutions suitable for mobile users and untrusted environments. Our method leverages the fact that mobile users often bring their own cell phones, and also takes into account different levels of security adapted for different services on the Web. Another important trend in the authentication landscape is that an increasing number of websites use third-party authentication. This is a solution where users have an account on a single system, the identity provider, and this one account can then be used with multiple other websites. In addition to requiring fewer passwords, these services can also in some cases implement authentication with higher security than passwords can provide. How websites select their third-party identity providers has privacy and security implications for end users. To better understand the security and privacy risks with these services, we present a data collection methodology that we have used to identify and capture third-party authentication usage on the Web. We have also characterized the third-party authentication landscape based on our collected data, outlining which types of third-parties are used by which types of sites, and how usage differs across the world. Using a combination of large-scale crawling, longitudinal manual testing, and in-depth login tests, our characterization and analysis has also allowed us to discover interesting structural properties of the landscape, differences in the cross-site relationships, and how the use of third-party authentication is changing over time. Finally, we have also outlined what information is shared between websites in third-party authentication, dened risk classes based on shared data, and proled privacy leakage risks associated with websites and their identity providers sharing data with each other. Our ndings show how websites can strengthen the privacy of their users based on how these websites select and combine their third-parties and the data they allow to be shared.

Completion Of Ontologies And Ontology Networks

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Author : Zlatan Dragisic
language : en
Publisher: Linköping University Electronic Press
Release Date : 2017-08-22

Completion Of Ontologies And Ontology Networks written by Zlatan Dragisic and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-08-22 with Computers categories.

The World Wide Web contains large amounts of data, and in most cases this data has no explicit structure. The lack of structure makes it difficult for automated agents to understand and use such data. A step towards a more structured World Wide Web is the Semantic Web, which aims at introducing semantics to data on the World Wide Web. One of the key technologies in this endeavour are ontologies, which provide a means for modeling a domain of interest and are used for search and integration of data. In recent years many ontologies have been developed. To be able to use multiple ontologies it is necessary to align them, i.e., find inter-ontology relationships. However, developing and aligning ontologies is not an easy task and it is often the case that ontologies and their alignments are incorrect and incomplete. This can be a problem for semantically-enabled applications. Incorrect and incomplete ontologies and alignments directly influence the quality of the results of such applications, as wrong results can be returned and correct results can be missed. This thesis focuses on the problem of completing ontologies and ontology networks. The contributions of the thesis are threefold. First, we address the issue of completing the is-a structure and alignment in ontologies and ontology networks. We have formalized the problem of completing the is-a structure in ontologies as an abductive reasoning problem and developed algorithms as well as systems for dealing with the problem. With respect to the completion of alignments, we have studied system performance in the Ontology Alignment Evaluation Initiative, a yearly evaluation campaign for ontology alignment systems. We have also addressed the scalability of ontology matching, which is one of the current challenges, by developing an approach for reducing the search space when generating the alignment.Second, high quality completion requires user involvement. As users' time and effort are a limited resource we address the issue of limiting and facilitating user interaction in the completion process. We have conducted a broad study of state-of-the-art ontology alignment systems and identified different issues related to the process. We have also conducted experiments to assess the impact of user errors in the completion process. While the completion of ontologies and ontology networks can be done at any point in the life-cycle of ontologies and ontology networks, some of the issues can be addressed already in the development phase. The third contribution of the thesis addresses this by introducing ontology completion and ontology alignment into an existing ontology development methodology.

Parameterized Verification Of Synchronized Concurrent Programs

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Author : Zeinab Ganjei
language : en
Publisher: Linköping University Electronic Press
Release Date : 2021-03-19

Parameterized Verification Of Synchronized Concurrent Programs written by Zeinab Ganjei and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-03-19 with categories.

There is currently an increasing demand for concurrent programs. Checking the correctness of concurrent programs is a complex task due to the interleavings of processes. Sometimes, violation of the correctness properties in such systems causes human or resource losses; therefore, it is crucial to check the correctness of such systems. Two main approaches to software analysis are testing and formal verification. Testing can help discover many bugs at a low cost. However, it cannot prove the correctness of a program. Formal verification, on the other hand, is the approach for proving program correctness. Model checking is a formal verification technique that is suitable for concurrent programs. It aims to automatically establish the correctness (expressed in terms of temporal properties) of a program through an exhaustive search of the behavior of the system. Model checking was initially introduced for the purpose of verifying finite‐state concurrent programs, and extending it to infinite‐state systems is an active research area. In this thesis, we focus on the formal verification of parameterized systems. That is, systems in which the number of executing processes is not bounded a priori. We provide fully-automatic and parameterized model checking techniques for establishing the correctness of safety properties for certain classes of concurrent programs. We provide an open‐source prototype for every technique and present our experimental results on several benchmarks. First, we address the problem of automatically checking safety properties for bounded as well as parameterized phaser programs. Phaser programs are concurrent programs that make use of the complex synchronization construct of Habanero Java phasers. For the bounded case, we establish the decidability of checking the violation of program assertions and the undecidability of checking deadlock‐freedom. For the parameterized case, we study different formulations of the verification problem and propose an exact procedure that is guaranteed to terminate for some reachability problems even in the presence of unbounded phases and arbitrarily many spawned processes. Second, we propose an approach for automatic verification of parameterized concurrent programs in which shared variables are manipulated by atomic transitions to count and synchronize the spawned processes. For this purpose, we introduce counting predicates that related counters that refer to the number of processes satisfying some given properties to the variables that are directly manipulated by the concurrent processes. We then combine existing works on the counter, predicate, and constrained monotonic abstraction and build a nested counterexample‐based refinement scheme to establish correctness. Third, we introduce Lazy Constrained Monotonic Abstraction for more efficient exploration of well‐structured abstractions of infinite‐state non‐monotonic systems. We propose several heuristics and assess the efficiency of the proposed technique by extensive experiments using our open‐source prototype. Lastly, we propose a sound but (in general) incomplete procedure for automatic verification of safety properties for a class of fault‐tolerant distributed protocols described in the Heard‐Of (HO for short) model. The HO model is a popular model for describing distributed protocols. We propose a verification procedure that is guaranteed to terminate even for unbounded number of the processes that execute the distributed protocol.

Designing Human Swarm Interaction Systems

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Author : Oscar Bjurling
language : en
Publisher: Linköping University Electronic Press
Release Date : 2025-02-20

Designing Human Swarm Interaction Systems written by Oscar Bjurling and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2025-02-20 with categories.

Swarms of Unmanned Aerial Vehicles (UAVs, or drones) are envisioned to transform various fields, from emergency response to law enforcement and military operations. Drone swarms provide scalable, adaptable, and decentralized solutions for dynamic work environments. However, the successful integration of these multi-agent systems into real-world settings presents significant challenges, particularly in terms of how humans can safely and effectively interact with and control these systems. Human-Swarm Interaction (HSI) aims to address these challenges by exploring how human operators can manage multiple drones in a cohesive manner, even under highly complex, uncertain conditions. This thesis studies the problem of designing effective interaction mechanisms and interfaces for human operators to command drone swarms, specifically addressing challenges such as managing a large number of drones, supporting operators’ situational awareness, and balancing between centralized and decentralized control. The research highlights the necessity of rethinking conventional approaches by introducing alternative conceptual models, such as the "choir" metaphor, which re-imagines drone swarms as coordinated, semi-centralized ensembles rather than purely emergent, decentralized collectives. This metaphor aims to balance the collective, often unpredictable behavior of drone swarms with the predictable, directed actions needed in operational environments. By demonstrating how this metaphor can be operationalized in an HSI system architecture, the thesis provides new avenues for conceptualizing human interaction with autonomous systems. Using a design research approach incorporating multiple-case study and scenario-based design activities to envision future swarm application in dialogue with prospective end users, the thesis develops and evaluates prototypes that embody these nuanced HSI concepts. The interface prototypes draw design inspiration from Real-Time Strategy (RTS) games. These elements include group commands, high-level mission planning, and resource pooling to create a hybrid interaction model that allows operators to maintain both a broad overview and precise control of multiple autonomous and collaborating drones. Domain expert evaluations of these prototypes in contexts such as firefighting and airport management validate the practical utility of these concepts. The findings emphasize the value of adopting a Human-Technology-Organization (HTO) perspective in the design of HSI systems. Rather than focusing solely on the interaction between humans and technology, this systems-thinking approach acknowledges that drone swarms must be integrated into larger organizational frameworks, such as emergency response command structures or airport ground operations teams. It demonstrates that successful deployment requires accounting for the broader organizational context, including roles, workflows, and coordination needs. This holistic approach to HSI system design ensures that drone swarms not only meet technical performance criteria, such as reliability, responsiveness, and scalability, but also align with human and organizational needs, facilitating their adoption and effective use in a wide range of real-world scenarios. Ultimately, these contributions are intended to bridge the gap between theoretical models of swarm control and practical deployment, advancing both the field of HSI and the broader adoption of drone swarm technologies. Svärmar av obemannade luftfarkoster (UAV, eller drönare) förväntas omvandla flera områden, exempelvis räddningsinsatser, brottsbekämpning, och militäroperationer. Drönarsvärmar innebar skalbara, anpassningsbara, och decentraliserade lösningar for dynamiska arbetsuppgifter. Den lyckade integreringen av dessa multi-agent-system i verkliga miljöer innebar dock betydande utmaningar, särskilt med avseende på hur människor säkert och effektivt interagerar med och kontrollerar dessa system. Forskningsfältet Människa-Svärm Interaktion (MSI) syftar till att möta dessa utmaningar genom att undersöka hur mänskliga operatorer kan hantera flera drönare på ett sammanhängande vis, även under komplexa och osäkra förhållanden. Denna avhandling utreder problemet att utforma effektiva och säkra interaktionsmekanismer och gränssnitt for mänskliga operatorer att leda drönarsvärmar, specifikt genom att adressera utmaningar som att hantera ett stort antal drönare, stödja operatorers situationsmedvetenhet, och balansera mellan centraliserad och decentraliserad kontroll. Avhandlingen betonar vikten av att ifrågasatta konventionella tillvägagångssätt genom att introducera alternativa konceptuella modeller, såsom "kör"-metaforen, som omtolkar drönarsvärmar som koordinerade, semicentraliserade ensembler snarare än rent decentraliserade kollektiv. Denna metafor syftar till att balansera det kollektiva, ofta oförutsägbara beteendet hos drönarsvärmar med de förutsägbara, riktade handlingar som behövs i operativa miljöer. Genom att visa hur denna metafor kan operationaliseras i en MSI-systemarkitektur, erbjuder avhandlingen nya sätt att konceptualisera mänsklig interaktion med autonoma system. Genom att tillämpa en designforskningsmetod som innefattar fallstudier och scenariobaserade designaktiviteter för att föreställa sig framtida svärmtillämpningar i dialog med potentiella slutanvändare, utvecklar och utvärderar avhandlingen prototyper som manifesterar dessa nyanserade MSI-koncept. Gränssnittens prototyper drar designinspiration från realtidsstrategispel (RTS). Dessa element inkluderar enhetshantering och kommandon på gruppnivå, strategisk uppdragsplanering, och resursdelning för att skapa en hybrid interaktionsmodell som gör det möjligt för operatörer att både bibehålla en bred lägesbild och utöva precis kontroll över flera autonoma och samverkande drönare. Domänexperters utvärderingar av dessa prototyper i arbetskontexter som brandbekämpning och flygplatsledning påvisar den praktiska användbarheten av dessa koncept. Resultaten betonar värdet av att anta ett Människa-Teknik-Organisation (MTO)-perspektiv vid utformningen av MSI-system. Snarare än att enbart fokusera på interaktionen mellan människor och teknik, erkänner detta systemtänkande tillvägagångssätt att drönarsvärmar måste integreras i större organisatoriska ramar, såsom ledningsstrukturer for räddningsinsatser eller markoperativa team på flygplatser. Det visar att framgångsrik implementering av drönarsvärmar kräver att systemutvecklare tar hänsyn till det bredare organisatoriska sammanhanget, inklusive roller, arbetsflöden, och samverkansbehov. Detta holistiska tillvägagångssatt för utformningen av MSI-system säkerställer att drönarsvärmar inte bara uppfyller tekniska prestandakriterier, såsom tillförlitlighet, responsivitet, och skalbarhet, utan också överensstämmer med mänskliga och organisatoriska behov, vilket underlättar deras införande och effektiv användning i en mängd olika tillämpningsscenarier. Över lag är dessa forskningsbidrag avsedda att överbrygga gapet mellan teoretiska modeller för svärmstyrning och praktisk implementering, och därmed avancera och främja både MSI-området och den bredare användningen av svärmteknologier.

Human Centred Design Of Socially Interactive Virtual Agents

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Author : Emma Mainza Chilufya
language : en
Publisher: Linköping University Electronic Press
Release Date : 2025-02-24

Human Centred Design Of Socially Interactive Virtual Agents written by Emma Mainza Chilufya and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2025-02-24 with categories.

The thesis is within the field of cognitive science, set within the domains of situated cognition and mediated action with a focus on mediation in Human- Computer Interaction (HCI). It discusses cognition in relation to users, Intelligent Virtual Agents (IVAs), and the interaction environment. The perspectives and actions of users (humans) significantly influence the course of the interaction. IVAs as mediators facilitate interactions between users and their environments. As agents, they actively engage with users, influencing their decisions and behaviours. User involvement in the design process is important for the design of interactive systems. When properly implemented, using the correct methods, principles, and techniques can lead to the development of systems that are effective, efficient, and satisfying to use. IVA research has shown a lack of user participation methodologies in the design process. The design of IVAs often focuses on individual elements and not the IVA as an integrated whole. As a result, these design insights do not easily convert into actionable guidelines. User involvement is primarily seen during the evaluation phase. This leads to the purpose of looking at the design of interactive interfaces of embodied agents (virtual and physical) set in social interactive spaces by involving the users in the conceptual generation and prototyping phase. The research questions are: How can we design interactive virtual agents for social interactive spaces? and How can we apply human-centred design methods to develop interactive virtual agents for social interactive spaces? Two case studies: a virtual receptionist for a university department and a reading robot (BookBot) for fourth-grade pupils are conducted. Each case study involved a concept generation and prototyping phase with the users using human-centred design (HCD) methods and tools. Prototypes were developed based on the conceptual phase findings and evaluated with the users. One key contribution is the application of HCD methodologies in the design of IVAs within social interactive spaces. This includes considerations of the context of interaction: mediation patterns, and the spaces of interaction. Another contribution is the introduction of novel design approaches/ solution features and competencies that designers should have when designing IVAs in social interactive spaces. The thesis presents exemplars of IVAs in these spaces. Avhandlingen ligger inom området kognitiv vetenskap, med fokus på situerad kognition och medierad handling inom Human-Computer Interaction (HCI). Den diskuterar kognition i relation till användare, intelligenta virtuella agenter (IVAs) och interaktionsmiljön. Användarnas (människors) perspektiv och handlingar påverkar i hög grad interaktionens förlopp. IVAs som medlare underlättar interaktioner mellan användare och deras miljöer. Som agenter engagerar de sig aktivt med användare och påverkar deras beslut och beteenden. Användarinvolvering i designprocessen är viktig for utformningen av interaktiva system. När den genomförs korrekt, med rätt metoder, principer och tekniker, kan den leda till utveckling av system som är effektiva, ändamålsenliga och tillfredsställande att använda. Forskning om IVAs har visat en brist på användarmetoder i designprocessen. Designen av IVAs fokuserar ofta på individuella element och inte på IVA som en integrerad helhet. Som ett resultat är dessa designinsikter svara att omvandla till handlingsbara riktlinjer. Användardeltagande ses främst under utvärderingsfasen. Detta leder till syftet att undersöka designen av interaktiva gränssnitt för forkroppsligade agenter (virtuella och fysiska) i sociala interaktiva utrymmen genom att involvera användarna i den konceptuella genereringen och prototypfasen. Forskningsfrågorna är: Hur kan vi designa interaktiva virtuella agenter for sociala interaktiva utrymmen? och Hur kan vi tillämpa användarcentrerade designmetoder för att utveckla interaktiva virtuella agenter för sociala interaktiva utrymmen? Två fallstudier: en virtuell receptionist för en universitetsavdelning och en läsrobot (BookBot) för fjärdeklassare utförs. Varje fallstudie involverade en konceptgenererings- och prototypfas med användarna med hjälp av användarcentrerade designmetoder och verktyg. Prototyper utvecklades baserat på resultaten från den konceptuella fasen och utvärderades med användarna. Ett viktigt bidrag är tillämpningen av användarcentrerade designmetoder i designen av IVAs inom sociala interaktiva utrymmen. Detta inkluderar överväganden av interaktionskontexten: medlingsmönster och interaktionsutrymmen. Ett annat bidrag är introduktionen av nya designmetoder/lösningsfunktioner och kompetenser som designers bör ha när de designar IVAs i sociala interaktiva utrymmen. Avhandlingen presenterar exempel på IVAs i dessa utrymmen.

Studying Simulations With Distributed Cognition

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Author : Jonas Rybing
language : en
Publisher: Linköping University Electronic Press
Release Date : 2018-03-20

Studying Simulations With Distributed Cognition written by Jonas Rybing and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-03-20 with categories.

Simulations are frequently used techniques for training, performance assessment, and prediction of future outcomes. In this thesis, the term “human-centered simulation” is used to refer to any simulation in which humans and human cognition are integral to the simulation’s function and purpose (e.g., simulation-based training). A general problem for human-centered simulations is to capture the cognitive processes and activities of the target situation (i.e., the real world task) and recreate them accurately in the simulation. The prevalent view within the simulation research community is that cognition is internal, decontextualized computational processes of individuals. However, contemporary theories of cognition emphasize the importance of the external environment, use of tools, as well as social and cultural factors in cognitive practice. Consequently, there is a need for research on how such contemporary perspectives can be used to describe human-centered simulations, re-interpret theoretical constructs of such simulations, and direct how simulations should be modeled, designed, and evaluated. This thesis adopts distributed cognition as a framework for studying human-centered simulations. Training and assessment of emergency medical management in a Swedish context using the Emergo Train System (ETS) simulator was adopted as a case study. ETS simulations were studied and analyzed using the distributed cognition for teamwork (DiCoT) methodology with the goal of understanding, evaluating, and testing the validity of the ETS simulator. Moreover, to explore distributed cognition as a basis for simulator design, a digital re-design of ETS (DIGEMERGO) was developed based on the DiCoT analysis. The aim of the DIGEMERGO system was to retain core distributed cognitive features of ETS, to increase validity, outcome reliability, and to provide a digital platform for emergency medical studies. DIGEMERGO was evaluated in three separate studies; first, a usefulness, usability, and facevalidation study that involved subject-matter-experts; second, a comparative validation study using an expert-novice group comparison; and finally, a transfer of training study based on self-efficacy and management performance. Overall, the results showed that DIGEMERGO was perceived as a useful, immersive, and promising simulator – with mixed evidence for validity – that demonstrated increased general self-efficacy and management performance following simulation exercises. This thesis demonstrates that distributed cognition, using DiCoT, is a useful framework for understanding, designing and evaluating simulated environments. In addition, the thesis conceptualizes and re-interprets central constructs of human-centered simulation in terms of distributed cognition. In doing so, the thesis shows how distributed cognitive processes relate to validity, fidelity, functionality, and usefulness of human-centered simulations. This thesis thus provides a new understanding of human-centered simulations that is grounded in distributed cognition theory.

Orchestrating A Resource Aware Edge

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Author : Klervie Toczé
language : en
Publisher: Linköping University Electronic Press
Release Date : 2024-09-02

Orchestrating A Resource Aware Edge written by Klervie Toczé and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024-09-02 with Electronic books categories.

More and more services are moving to the cloud, attracted by the promise of unlimited resources that are accessible anytime, and are managed by someone else. However, hosting every type of service in large cloud datacenters is not possible or suitable, as some emerging applications have stringent latency or privacy requirements, while also handling huge amounts of data. Therefore, in recent years, a new paradigm has been proposed to address the needs of these applications: the edge computing paradigm. Resources provided at the edge (e.g., for computation and communication) are constrained, hence resource management is of crucial importance. The incoming load to the edge infrastructure varies both in time and space. Managing the edge infrastructure so that the appropriate resources are available at the required time and location is called orchestrating. This is especially challenging in case of sudden load spikes and when the orchestration impact itself has to be limited. This thesis enables edge computing orchestration with increased resource-awareness by contributing with methods, techniques, and concepts for edge resource management. First, it proposes methods to better understand the edge resource demand. Second, it provides solutions on the supply side for orchestrating edge resources with different characteristics in order to serve edge applications with satisfactory quality of service. Finally, the thesis includes a critical perspective on the paradigm, by considering sustainability challenges. To understand the demand patterns, the thesis presents a methodology for categorizing the large variety of use cases that are proposed in the literature as potential applications for edge computing. The thesis also proposes methods for characterizing and modeling applications, as well as for gathering traces from real applications and analyzing them. These different approaches are applied to a prototype from a typical edge application domain: Mixed Reality. The important insight here is that application descriptions or models that are not based on a real application may not be giving an accurate picture of the load. This can drive incorrect decisions about what should be done on the supply side and thus waste resources. Regarding resource supply, the thesis proposes two orchestration frameworks for managing edge resources and successfully dealing with load spikes while avoiding over-provisioning. The first one utilizes mobile edge devices while the second leverages the concept of spare devices. Then, focusing on the request placement part of orchestration, the thesis formalizes it in the case of applications structured as chains of functions (so-called microservices) as an instance of the Traveling Purchaser Problem and solves it using Integer Linear Programming. Two different energy metrics influencing request placement decisions are proposed and evaluated. Finally, the thesis explores further resource awareness. Sustainability challenges that should be highlighted more within edge computing are collected. Among those related to resource use, the strategy of sufficiency is promoted as a way forward. It involves aiming at only using the needed resources (no more, no less) with a goal of reducing resource usage. Different tools to adopt it are proposed and their use demonstrated through a case study.

Scalable And Efficient Probabilistic Topic Model Inference For Textual Data

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Author : Måns Magnusson
language : en
Publisher: Linköping University Electronic Press
Release Date : 2018-04-27

Scalable And Efficient Probabilistic Topic Model Inference For Textual Data written by Måns Magnusson and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-04-27 with categories.

Probabilistic topic models have proven to be an extremely versatile class of mixed-membership models for discovering the thematic structure of text collections. There are many possible applications, covering a broad range of areas of study: technology, natural science, social science and the humanities. In this thesis, a new efficient parallel Markov Chain Monte Carlo inference algorithm is proposed for Bayesian inference in large topic models. The proposed methods scale well with the corpus size and can be used for other probabilistic topic models and other natural language processing applications. The proposed methods are fast, efficient, scalable, and will converge to the true posterior distribution. In addition, in this thesis a supervised topic model for high-dimensional text classification is also proposed, with emphasis on interpretable document prediction using the horseshoe shrinkage prior in supervised topic models. Finally, we develop a model and inference algorithm that can model agenda and framing of political speeches over time with a priori defined topics. We apply the approach to analyze the evolution of immigration discourse in the Swedish parliament by combining theory from political science and communication science with a probabilistic topic model. Probabilistiska ämnesmodeller (topic models) är en mångsidig klass av modeller för att estimera ämnessammansättningar i större corpusar. Applikationer finns i ett flertal vetenskapsområden som teknik, naturvetenskap, samhällsvetenskap och humaniora. I denna avhandling föreslås nya effektiva och parallella Markov Chain Monte Carlo algoritmer för Bayesianska ämnesmodeller. De föreslagna metoderna skalar väl med storleken på corpuset och kan användas för flera olika ämnesmodeller och liknande modeller inom språkteknologi. De föreslagna metoderna är snabba, effektiva, skalbara och konvergerar till den sanna posteriorfördelningen. Dessutom föreslås en ämnesmodell för högdimensionell textklassificering, med tonvikt på tolkningsbar dokumentklassificering genom att använda en kraftigt regulariserande priorifördelningar. Slutligen utvecklas en ämnesmodell för att analyzera "agenda" och "framing" för ett förutbestämt ämne. Med denna metod analyserar vi invandringsdiskursen i Sveriges Riksdag över tid, genom att kombinera teori från statsvetenskap, kommunikationsvetenskap och probabilistiska ämnesmodeller.

Beyond Recognition

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Author : Le Minh-Ha
language : en
Publisher: Linköping University Electronic Press
Release Date : 2024-05-06

Beyond Recognition written by Le Minh-Ha and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024-05-06 with categories.

This thesis addresses the need to balance the use of facial recognition systems with the need to protect personal privacy in machine learning and biometric identification. As advances in deep learning accelerate their evolution, facial recognition systems enhance security capabilities, but also risk invading personal privacy. Our research identifies and addresses critical vulnerabilities inherent in facial recognition systems, and proposes innovative privacy-enhancing technologies that anonymize facial data while maintaining its utility for legitimate applications. Our investigation centers on the development of methodologies and frameworks that achieve k-anonymity in facial datasets; leverage identity disentanglement to facilitate anonymization; exploit the vulnerabilities of facial recognition systems to underscore their limitations; and implement practical defenses against unauthorized recognition systems. We introduce novel contributions such as AnonFACES, StyleID, IdDecoder, StyleAdv, and DiffPrivate, each designed to protect facial privacy through advanced adversarial machine learning techniques and generative models. These solutions not only demonstrate the feasibility of protecting facial privacy in an increasingly surveilled world, but also highlight the ongoing need for robust countermeasures against the ever-evolving capabilities of facial recognition technology. Continuous innovation in privacy-enhancing technologies is required to safeguard individuals from the pervasive reach of digital surveillance and protect their fundamental right to privacy. By providing open-source, publicly available tools, and frameworks, this thesis contributes to the collective effort to ensure that advancements in facial recognition serve the public good without compromising individual rights. Our multi-disciplinary approach bridges the gap between biometric systems, adversarial machine learning, and generative modeling to pave the way for future research in the domain and support AI innovation where technological advancement and privacy are balanced.

Gated Bayesian Networks

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Author : Marcus Bendtsen
language : en
Publisher: Linköping University Electronic Press
Release Date : 2017-06-08

Gated Bayesian Networks written by Marcus Bendtsen and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-06-08 with categories.

Bayesian networks have grown to become a dominant type of model within the domain of probabilistic graphical models. Not only do they empower users with a graphical means for describing the relationships among random variables, but they also allow for (potentially) fewer parameters to estimate, and enable more efficient inference. The random variables and the relationships among them decide the structure of the directed acyclic graph that represents the Bayesian network. It is the stasis over time of these two components that we question in this thesis. By introducing a new type of probabilistic graphical model, which we call gated Bayesian networks, we allow for the variables that we include in our model, and the relationships among them, to change overtime. We introduce algorithms that can learn gated Bayesian networks that use different variables at different times, required due to the process which we are modelling going through distinct phases. We evaluate the efficacy of these algorithms within the domain of algorithmic trading, showing how the learnt gated Bayesian networks can improve upon a passive approach to trading. We also introduce algorithms that detect changes in the relationships among the random variables, allowing us to create a model that consists of several Bayesian networks, thereby revealing changes and the structure by which these changes occur. The resulting models can be used to detect the currently most appropriate Bayesian network, and we show their use in real-world examples from both the domain of sports analytics and finance.