Towards a Dichotomy for the Possible Winner Problem in Elections Based on Scoring Rules

To make a joint decision, agents (or voters) are often required to provide their preferences as linear orders. To determine a winner, the given linear orders can be aggregated according to a voting protocol. However, in realistic settings, the voters may often only provide partial orders. This directly leads to the Possible Winner problem that asks, given a set of partial votes, whether a distinguished candidate can still become a winner. In this work, we consider the computational complexity of Possible Winner for the broad class of voting protocols defined by scoring rules. A scoring rule provides a score value for every position which a candidate can have in a linear order. Prominent examples include plurality, k-approval, and Borda. Generalizing previous NP-hardness results for some special cases, we settle the computational complexity for all but one scoring rule. More precisely, for an unbounded number of candidates and unweighted voters, we show that Possible Winner is NP-complete for all pure scoring rules except plurality, veto, and the scoring rule defined by the scoring vector (2,1,...,1,0), while it is solvable in polynomial time for plurality and veto.Comment: minor changes and updates; accepted for publication in JCSS, online version available

Synchroneity of major late Neogene sea level fluctuations and paleoceanographically controlled changes as recorded by two carbonate platforms

Shallow-water carbonate systems are reliable recorders of sea level fluctuations and changes in ambient seawater conditions. Drilling results from Ocean Drilling Program (ODP) Legs 133 and 166 indicate that the timing of late Neogene sedimentary breaks triggered by sea level lowerings is synchronous in the sedimentary successions of the Queensland Plateau and the Great Bahama Bank. This synchrony indicates that these sea level changes were eustatic in origin. The carbonate platforms were also affected by contemporary, paleoceanographically controlled fluctuations in carbonate production. Paleoceanographic changes are recorded at 10.7, 3.6, and 1.7–2.0 Ma. At the Queensland Plateau, sea surface temperature shifts are documented by shifts from tropical to temperate carbonates (10.7 Ma) and vice versa (3.6 Ma); the modern tropical platform was established at 2.0–1.8 Ma. At Great Bahama Bank, changes were registered in compositional variations of platform-derived sediment, such as major occurrence of peloids (3.6 Ma) and higher rates of neritic carbonate input (1.7 Ma). The synchroneity of these changes attests to the far-field effects of modifications in the oceanographic circulation on shallow-water, low-latitude carbonate production

Erziehung zur Autonomie als Elternpflicht

Parents have the duty (among others) to enhance the autonomy of their child. Someone can be regarded as autonomous if she knows what she really wants, and if she is able to guide herself over time in light of that. I first show that we are confronted with a puzzle: children can be characterized, in part at least, as not being sufficiently autonomous (if at all). To enhance the autonomy of a child, it must be subject to her parents' heteronomy. But how can a child then ever find out what it really wants for herself? In a second step, I defend the claim that a child needs to acquire the attitude of valuing. I propose a definition of valuing, and show that children already are proto-valuers. I then argue that personal projects are the adequate means to acquire the attitude of valuing. In discussing four objections I bolster the view that personal projects are constitutive for the autonomy of a child. They are therefore an important part of the parents' duty to enhance the child′s autonom

Dualities, extended geometries and the string landscape

This thesis is concerned with the role of dualities and nongeometric backgrounds in string theory. Dualities define nontrivial mappings by which seemingly distinct theories can be identified as alternative descriptions of the same physical reality. Their presence often suggests that the dual models are built upon more fundamental structures which cannot be fully captured by the applied formalisms. In string theory the web of dualities between the five consistent superstring theories served as a motivation to postulate the existence of an underlying M-theory. However, it was later observed that certain background fluxes are thereby mapped to objects which are ill-defined in conventional differential geometry. Such nongeometric backgrounds play an essential role in the field of string phenomenology. The first half of this work focuses on the application of extended field theories to describe string theories on generalized backgrounds. An emphasis is thereby placed on dimensional reductions of type II double field theory, which allows for a local description of type II supergravities with geometric and nongeometric fluxes. We show explicitly by the examples of Calabi-Yau manifolds and K3xT^2 that the effective four-dimensional action of such models is described by gauged supergravities in which all appearing moduli are stabilized. The role of the fluxes in respect of the structure of the effective action and the relation to other approaches to flux compactifications are discussed in detail. The second half of this thesis is built around the statistical analysis of string vacua in orientifold compactifications with fluxes. A major focus is thereby set on the interplay between dualities and the so-called tadpole-cancellation condition. We demonstrate at the example of T^6/Z2xZ2 that only a small fraction of the computed vacua is located in a region for which both a perturbative approach and a probe approximation for D-branes are reliable. In addition, we show that the vacua often accumulate on submanifolds of the full moduli space and that there exist certain voids in which no values are stabilized under the given assumptions. The issues of moduli stabilization and model building are therefore closely intertwined, and a unified treatment might provide valuable insights into the structure of the string landscape

The Right to Associational Freedom and the Scope of Relationship-Dependent Duties

Humans have a fundamental need to belong. This, need, as Kimberley Brownlee argues in her book Being Sure of Each Other grounds the human right against social deprivation. But in addition to having a human right against social deprivation, we also have a right to associational freedom, which is grounded in our right to autonomy. We cannot be forced into relationships;we are free to choose our friends and loved ones.? In this paper I discuss what our right to associational freedom morally permits us to do when are already in an intimate relationship and, relatedly, what our relationship-dependent duties require of us in such cases. What exactly are the constraints on our right to associational freedom? And what is the content and scope of our relationship-dependent duties, given that our right to associational freedom conflicts with the fulfillment of these duties?? After providing some clarifications as to how we should understand intimate relationships that have ended, I will first highlight what relationship-dependent duties are and how they correlate with a right to associational control. I will then discuss several break-up scenarios, the aim of which is to determine the conditions that justify constraints being imposed on the right to associational freedom and to delineate the scope of relationship-dependent duties

Is statistical learning a mechanism?

Philosophers of science have offered several definitions of mechanism, most of which have biological or neuroscientific roots. In this paper, I consider whether these definitions apply equally well to cognitive science. I examine this question by looking at the case of statistical learning, which has been called a domain-general learning mechanism in the cognitive scientific literature. I argue that statistical learning does not constitute a mechanism in the philosophical sense of the term. This conclusion points to significant limitations in the scope of the mechanist philosophy when it comes to accounting for explanation in cognitive science.The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement no 284123.This is the author accepted manuscript. The final version is available from Taylor & Francis via http://dx.doi.org/10.1080/09515089.2016.116717

Dualities, extended geometries and the string landscape

This thesis is concerned with the role of dualities and nongeometric backgrounds in string theory. Dualities define nontrivial mappings by which seemingly distinct theories can be identified as alternative descriptions of the same physical reality. Their presence often suggests that the dual models are built upon more fundamental structures which cannot be fully captured by the applied formalisms. In string theory the web of dualities between the five consistent superstring theories served as a motivation to postulate the existence of an underlying M-theory. However, it was later observed that certain background fluxes are thereby mapped to objects which are ill-defined in conventional differential geometry. Such nongeometric backgrounds play an essential role in the field of string phenomenology. The first half of this work focuses on the application of extended field theories to describe string theories on generalized backgrounds. An emphasis is thereby placed on dimensional reductions of type II double field theory, which allows for a local description of type II supergravities with geometric and nongeometric fluxes. We show explicitly by the examples of Calabi-Yau manifolds and K3xT^2 that the effective four-dimensional action of such models is described by gauged supergravities in which all appearing moduli are stabilized. The role of the fluxes in respect of the structure of the effective action and the relation to other approaches to flux compactifications are discussed in detail. The second half of this thesis is built around the statistical analysis of string vacua in orientifold compactifications with fluxes. A major focus is thereby set on the interplay between dualities and the so-called tadpole-cancellation condition. We demonstrate at the example of T^6/Z2xZ2 that only a small fraction of the computed vacua is located in a region for which both a perturbative approach and a probe approximation for D-branes are reliable. In addition, we show that the vacua often accumulate on submanifolds of the full moduli space and that there exist certain voids in which no values are stabilized under the given assumptions. The issues of moduli stabilization and model building are therefore closely intertwined, and a unified treatment might provide valuable insights into the structure of the string landscape

CoAP congestion control for the Internet of Things

“© © 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.” August Betzler, Javier Isern, Carles Gomez, Ilker Demirkol, Josep Paradells, "Experimental evaluation of congestion control for CoAP communications without end-to-end reliability", Ad Hoc Networks, pp. , 2016, ISSN 15708705. DOI: 10.1109/MCOM.2016.7509394CoAP is a lightweight RESTful application layer protocol devised for the IoT. Operating on top of UDP, CoAP must handle congestion control by itself. The core CoAP specification defines a basic congestion control mechanism, but it is not capable of adapting to network conditions. However, IoT scenarios exhibit significant resource constraints, which pose new challenges on the design of congestion control mechanisms. In this article we present CoCoA, an advanced congestion control mechanism for CoAP being standardized by the Internet Engineering Task Force CoRE working group. CoCoA introduces a novel round-trip time estimation technique, together with a variable backoff factor and aging mechanisms in order to provide dynamic and controlled retransmission timeout adaptation suitable for the peculiarities of IoT communications. We conduct a comparative performance analysis of CoCoA and a variety of alternative algorithms including state-of-the-art mechanisms developed for TCP. The study is based on experiments carried out in real testbeds. Results show that, in contrast to the alternative methods considered, CoCoA consistently outperforms the default CoAP congestion control mechanism in all evaluated scenarios.Peer ReviewedPostprint (author's final draft

13. Tagung des Forums Kultur und Ökonomie

Seit 2001 lädt das Forum Kultur und Ökonomie (FKÖ) die öffentlichen und privaten Kulturfinanzierenden ein, das Wissen über die Wechselwirkungen zwischen der wirtschaftlichen und politischen Dimension in der Kulturförderung zu vertiefen. Rund 130 Teilnehmende aus der gesamten Schweiz sowie Referierende aus Deutschland, den Niederlanden und Frankreich trafen sich dieses Jahr, um die künftige Rolle der Kunst und damit jener der Kulturfinanzierer im öffentlichen Raum zu diskutieren. Hintergrund der Diskussion sind vielfältige Herausforderungen, die sich aus Spannungen zwischen lokaler Planung und Partizipation sowie Forderungen unterschiedlichster öffentlicher, wirtschaftlicher und zivilgesellschaftlicher Instanzen ergeben