583 research outputs found
Machine-Readable Privacy Certificates for Services
Privacy-aware processing of personal data on the web of services requires
managing a number of issues arising both from the technical and the legal
domain. Several approaches have been proposed to matching privacy requirements
(on the clients side) and privacy guarantees (on the service provider side).
Still, the assurance of effective data protection (when possible) relies on
substantial human effort and exposes organizations to significant
(non-)compliance risks. In this paper we put forward the idea that a privacy
certification scheme producing and managing machine-readable artifacts in the
form of privacy certificates can play an important role towards the solution of
this problem. Digital privacy certificates represent the reasons why a privacy
property holds for a service and describe the privacy measures supporting it.
Also, privacy certificates can be used to automatically select services whose
certificates match the client policies (privacy requirements).
Our proposal relies on an evolution of the conceptual model developed in the
Assert4Soa project and on a certificate format specifically tailored to
represent privacy properties. To validate our approach, we present a worked-out
instance showing how privacy property Retention-based unlinkability can be
certified for a banking financial service.Comment: 20 pages, 6 figure
Cooking pasta with Lie groups
We extend the (gauged) Skyrme model to the case in which the global isospin group (which usually is taken to be SU(N)) is a generic compact connected Lie group G. We analyze the corresponding field equations in (3+1) dimensions from a group theory point of view. Several solutions can be constructed analytically and are determined by the embeddings of three dimensional simple Lie groups into G, in a generic irreducible representation. These solutions represent the so-called nuclear pasta state configurations of nuclear matter at low energy. We employ the Dynkin explicit classification of all three dimensional Lie subgroups of exceptional Lie group to classify all such solutions in the case G is an exceptional simple Lie group, and give all ingredients to construct them explicitly. As an example, we construct the explicit solutions for G=G2. We then extend our ansatz to include the minimal coupling of the Skyrme field to a U(1) gauge field. We extend the definition of the topological charge to this case and then concentrate our attention to the electromagnetic case. After imposing a \u201cfree force condition\u201d on the gauge field, the complete set of coupled field equations corresponding to the gauged Skyrme model minimally coupled to an Abelian gauge field is reduced to just one linear ODE keeping alive the topological charge. We discuss the cases in which such ODE belongs to the (Whittaker-)Hill and Mathieu types
Symmetry breaking, conformal geometry and gauge invariance
When the electroweak action is rewritten in terms of SU(2) gauge invariant
variables, the Higgs can be interpreted as a conformal metric factor. We show
that asymptotic flatness of the metric is required to avoid a Gribov problem:
without it, the new variables fail to be nonperturbatively gauge invariant. We
also clarify the relations between this approach and unitary gauge fixing, and
the existence of similar transformations in other gauge theories.Comment: 11 pages. Version 2: typos corrected, discussion of Elitzur's theorem
added. Version to appear in J.Phys.
Spin-1 gravitational waves
Gravitational fields invariant for a 2-dimensional Lie algebra of Killing
fields [ X,Y] =Y, with Y of light type, are analyzed. The conditions for them
to represent gravitational waves are verified and the definition of energy and
polarization is addressed; realistic generating sources are described.Comment: 18 pages, no figures. A section on possible sources has been added.
Version accepted for publication in Int. J. Mod. Phys.
Potts model on recursive lattices: some new exact results
We compute the partition function of the Potts model with arbitrary values of
and temperature on some strip lattices. We consider strips of width
, for three different lattices: square, diced and `shortest-path' (to be
defined in the text). We also get the exact solution for strips of the Kagome
lattice for widths . As further examples we consider two lattices
with different type of regular symmetry: a strip with alternating layers of
width and , and a strip with variable width. Finally we make
some remarks on the Fisher zeros for the Kagome lattice and their large
q-limit.Comment: 17 pages, 19 figures. v2 typos corrected, title changed and
references, acknowledgements and two further original examples added. v3 one
further example added. v4 final versio
Nonlinear Gravitational Waves: Their Form and Effects
A gravitational wave must be nonlinear to be able to transport its own
source, that is, energy and momentum. A physical gravitational wave, therefore,
cannot be represented by a solution to a linear wave equation. Relying on this
property, the second-order solution describing such physical waves is obtained.
The effects they produce on free particles are found to consist of nonlinear
oscillations along the direction of propagation.Comment: 15 pages, no figures. v2: presentation changes aiming at clarifying
the text; matches published versio
A study of the zero modes of the Faddeev-Popov operator in Euclidean Yang-Mills theories in the Landau gauge in d=2,3,4 dimensions
Examples of normalizable zero modes of the Faddeev-Popov operator in SU(2)
Euclidean Yang-Mills theories in the Landau gauge are constructed in d=2,3,4
dimensions.Comment: 18 pages. Text modifications. References added. Version accepted for
publication in the EPJ
Effects of Test-Driven Development : A Comparative Analysis of Empirical Studies
Test-driven development is a software development practice where small sections of test code are used to direct the development of program units. Writing test code prior to the production code promises several positive effects on the development process itself and on associated products and processes as well. However, there are few comparative studies on the effects of test-driven development. Thus, it is difficult to assess the potential process and product effects when applying test-driven development. In order to get an overview of the observed effects of test-driven development, an in-depth review of existing empirical studies was carried out. The results for ten different internal and external quality attributes indicate that test-driven development can reduce the amount of introduced defects and lead to more maintainable code. Parts of the implemented code may also be somewhat smaller in size and complexity. While maintenance of test-driven code can take less time, initial development may last longer. Besides the comparative analysis, this article sketches related work and gives an outlook on future research.Peer reviewe
An Empirical Study of Bots in Software Development -- Characteristics and Challenges from a Practitioner's Perspective
Software engineering bots - automated tools that handle tedious tasks - are
increasingly used by industrial and open source projects to improve developer
productivity. Current research in this area is held back by a lack of consensus
of what software engineering bots (DevBots) actually are, what characteristics
distinguish them from other tools, and what benefits and challenges are
associated with DevBot usage. In this paper we report on a mixed-method
empirical study of DevBot usage in industrial practice. We report on findings
from interviewing 21 and surveying a total of 111 developers. We identify three
different personas among DevBot users (focusing on autonomy, chat interfaces,
and "smartness"), each with different definitions of what a DevBot is, why
developers use them, and what they struggle with. We conclude that future
DevBot research should situate their work within our framework, to clearly
identify what type of bot the work targets, and what advantages practitioners
can expect. Further, we find that there currently is a lack of general purpose
"smart" bots that go beyond simple automation tools or chat interfaces. This is
problematic, as we have seen that such bots, if available, can have a
transformative effect on the projects that use them.Comment: To be published at the ACM Joint European Software Engineering
Conference and Symposium on the Foundations of Software Engineering
(ESEC/FSE
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