5,357 research outputs found
Subsidiarity and Proportionality in the Single Market: An EU fit for inclusive growth
This report offers a fresh perspective on the principles of subsidiarity and proportionality in the European Union based on a thorough-going economic analysis. Specifically, the report uses the EU Single Market as a case to discuss shortcomings and potential improvements in five key policy areas. It reviews how the principles of subsid- iarity and proportionality can help boost growth in the EU at the aggregate country level – while at the same time allowing EU regions to benefit from growth. The report focuses on the regional level as economic growth has been uneven across the EU’s regions over the last decade and, consequently, growing disparities between re- gions have emerged. This alone merits a review on how we can reconcile the twin objectives in the future
Particle Creation at a Point Source by Means of Interior-Boundary Conditions
We consider a way of defining quantum Hamiltonians involving particle
creation and annihilation based on an interior-boundary condition (IBC) on the
wave function, where the wave function is the particle-position representation
of a vector in Fock space, and the IBC relates (essentially) the values of the
wave function at any two configurations that differ only by the creation of a
particle. Here we prove, for a model of particle creation at one or more point
sources using the Laplace operator as the free Hamiltonian, that a Hamiltonian
can indeed be rigorously defined in this way without the need for any
ultraviolet regularization, and that it is self-adjoint. We prove further that
introducing an ultraviolet cut-off (thus smearing out particles over a positive
radius) and applying a certain known renormalization procedure (taking the
limit of removing the cut-off while subtracting a constant that tends to
infinity) yields, up to addition of a finite constant, the Hamiltonian defined
by the IBC.Comment: 41 page
Dynamic Complexity Meets Parameterised Algorithms
Dynamic Complexity studies the maintainability of queries with logical formulas in a setting where the underlying structure or database changes over time. Most often, these formulas are from first-order logic, giving rise to the dynamic complexity class DynFO. This paper investigates extensions of DynFO in the spirit of parameterised algorithms. In this setting structures come with a parameter k and the extensions allow additional "space" of size f(k) (in the form of an additional structure of this size) or additional time f(k) (in the form of iterations of formulas) or both. The resulting classes are compared with their non-dynamic counterparts and other classes. The main part of the paper explores the applicability of methods for parameterised algorithms to this setting through case studies for various well-known parameterised problems
Introduction to Iltis: An Interactive, Web-Based System for Teaching Logic
Logic is a foundation for many modern areas of computer science. In
artificial intelligence, as a basis of database query languages, as well as in
formal software and hardware verification --- modelling scenarios using logical
formalisms and inferring new knowledge are important skills for going-to-be
computer scientists. The Iltis project aims at providing a web-based,
interactive system that supports teaching logical methods. In particular the
system shall (a) support to learn to model knowledge and to infer new knowledge
using propositional logic, modal logic and first-order logic, and (b) provide
immediate feedback and support to students. This article presents a
prototypical system that currently supports the above tasks for propositional
logic. First impressions on its use in a second year logic course for computer
science students are reported
Dynamic Constant Time Parallel Graph Algorithms with Sub-Linear Work
The paper proposes dynamic parallel algorithms for connectivity and bipartiteness of undirected graphs that require constant time and ?(n^{1/2+?}) work on the CRCW PRAM model. The work of these algorithms almost matches the work of the ?(log n) time algorithm for connectivity by Kopelowitz et al. (2018) on the EREW PRAM model and the time of the sequential algorithm for bipartiteness by Eppstein et al. (1997). In particular, we show that the sparsification technique, which has been used in both mentioned papers, can in principle also be used for constant time algorithms in the CRCW PRAM model, despite the logarithmic depth of sparsification trees
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