Existence versus Exploitation: The Opacity of Backbones and Backdoors Under a Weak Assumption

Backdoors and backbones of Boolean formulas are hidden structural properties. A natural goal, already in part realized, is that solver algorithms seek to obtain substantially better performance by exploiting these structures. However, the present paper is not intended to improve the performance of SAT solvers, but rather is a cautionary paper. In particular, the theme of this paper is that there is a potential chasm between the existence of such structures in the Boolean formula and being able to effectively exploit them. This does not mean that these structures are not useful to solvers. It does mean that one must be very careful not to assume that it is computationally easy to go from the existence of a structure to being able to get one's hands on it and/or being able to exploit the structure. For example, in this paper we show that, under the assumption that P $\neq$ NP, there are easily recognizable families of Boolean formulas with strong backdoors that are easy to find, yet for which it is hard (in fact, NP-complete) to determine whether the formulas are satisfiable. We also show that, also under the assumption P $\neq$ NP, there are easily recognizable sets of Boolean formulas for which it is hard (in fact, NP-complete) to determine whether they have a large backbone

Constraint Satisfaction Techniques for Combinatorial Problems

The last two decades have seen extraordinary advances in tools and techniques for constraint satisfaction. These advances have in turn created great interest in their industrial applications. As a result, tools and techniques are often tailored to meet the needs of industrial applications out of the box. We claim that in the case of abstract combinatorial problems in discrete mathematics, the standard tools and techniques require special considerations in order to be applied effectively. The main objective of this thesis is to help researchers in discrete mathematics weave through the landscape of constraint satisfaction techniques in order to pick the right tool for the job. We consider constraint satisfaction paradigms like satisfiability of Boolean formulas and answer set programming, and techniques like symmetry breaking. Our contributions range from theoretical results to practical issues regarding tool applications to combinatorial problems. We prove search-versus-decision complexity results for problems about backbones and backdoors of Boolean formulas. We consider applications of constraint satisfaction techniques to problems in graph arrowing (specifically in Ramsey and Folkman theory) and computational social choice. Our contributions show how applying constraint satisfaction techniques to abstract combinatorial problems poses additional challenges. We show how these challenges can be addressed. Additionally, we consider the issue of trusting the results of applying constraint satisfaction techniques to combinatorial problems by relying on verified computations

Ethical Issues in Covert, Security and Surveillance Research

The ebook edition of this title is Open Access and freely available to read online. The EU-funded PRO-RES Project aimed to produce a guidance framework that helps to deliver Responsible Research and Innovation (RRI). PRO-RES is a Horizon 2020 project coordinated by the European Science Foundation (ESF), involving 14 different partners across Europe. As one of a series of open access products of the Project, Ethical Issues in Covert, Security and Surveillance Research will be placed in the hands of policymakers and their advisors to offer practical and efficient ways to respond to the issues addressed. Understanding that the problem of covert research and surveillance research for security purposes have proven highly challenging for all research ethics appraisal services, the chapters here are valuable resources for expert reviewers, helping further the discussion of these complex ethical issues, and raising the standards applied to the process. Delivering an applied approach, and influencing where it counts, this volume showcases that it is only when the integrity of research is carefully pursued can users of the evidence produced be assured of its value and its ethical credentials

Ethical Issues in Covert, Security and Surveillance Research

The ebook edition of this title is Open Access and freely available to read online. The EU-funded PRO-RES Project aimed to produce a guidance framework that helps to deliver Responsible Research and Innovation (RRI). PRO-RES is a Horizon 2020 project coordinated by the European Science Foundation (ESF), involving 14 different partners across Europe. As one of a series of open access products of the Project, Ethical Issues in Covert, Security and Surveillance Research will be placed in the hands of policymakers and their advisors to offer practical and efficient ways to respond to the issues addressed. Understanding that the problem of covert research and surveillance research for security purposes have proven highly challenging for all research ethics appraisal services, the chapters here are valuable resources for expert reviewers, helping further the discussion of these complex ethical issues, and raising the standards applied to the process. Delivering an applied approach, and influencing where it counts, this volume showcases that it is only when the integrity of research is carefully pursued can users of the evidence produced be assured of its value and its ethical credentials

Constructing and restraining the societies of surveillance: Accountability, from the rise of intelligence services to the expansion of personal data networks in Spain and Brazil (1975-2020)

541 p.The objective of this study is to examine the development of socio-technical accountability mechanisms in order to: a) preserve and increase the autonomy of individuals subjected to surveillance and b) replenish the asymmetry of power between those who watch and those who are watched. To do so, we address two surveillance realms: intelligence services and personal data networks. The cases studied are Spain and Brazil, from the beginning of the political transitions in the 1970s (in the realm of intelligence), and from the expansion of Internet digital networks in the 1990s (in the realm of personal data) to the present time. The examination of accountability, thus, comprises a holistic evolution of institutions, regulations, market strategies, as well as resistance tactics. The conclusion summarizes the accountability mechanisms and proposes universal principles to improve the legitimacy of authority in surveillance and politics in a broad sense

Tracking the Temporal-Evolution of Supernova Bubbles in Numerical Simulations

The study of low-dimensional, noisy manifolds embedded in a higher dimensional space has been extremely useful in many applications, from the chemical analysis of multi-phase flows to simulations of galactic mergers. Building a probabilistic model of the manifolds has helped in describing their essential properties and how they vary in space. However, when the manifold is evolving through time, a joint spatio-temporal modelling is needed, in order to fully comprehend its nature. We propose a first-order Markovian process that propagates the spatial probabilistic model of a manifold at fixed time, to its adjacent temporal stages. The proposed methodology is demonstrated using a particle simulation of an interacting dwarf galaxy to describe the evolution of a cavity generated by a Supernov