Translating E/R-diagrams into consistent database specifications

Semi formal methods, for example those which are used in the database community, are useful for communication between developers and clients. But they are not useful for formal verification.To overcome this problem it is possible to translate E/R-diagrams into first order algebraic specifications. The aim of our task was to prove the consistency of such translate specifications. To realize the proof we use the KIV (Karlsruhe Interactive Verifier) approach for the development of correct large software systems, i.e. we prove the consistency indirect by proving the correctness of an implementation. For this purpose we automatically translate E/R-diagrams not only in an algebraic specification, but in a modular system containing structured specifications and implementations. For a concrete E/R-diagram we can prove the correctness with the KIV system. Because the translation is uniform a generalized handmade proof for arbitrary but fixed E/R-diagrams is possible, and presented in this paper. This paper also includes an exemplary translation of an E/R-diagram with 5 entities and 6 relations. The generated modular system contains 33 specifications with more than 300 specified operations and more than 500 axioms. Furthermore the implementation contains more than 2200 lines of code

Integrating processes in temporal logic

In this paper we propose a technique to integrate process models in classical structures for quantified temporal (modal) logic. The idea is that in a temporal logic processes are ordinary syntactical objects with a specific semantical representation. So we want to achieve a `temporal logics of processes\u27 to adequately describe aspects of systems dealing with data structures, reactive and time-critical behavior, environmental influences, and their interaction in a single frame. Thus the structural information of processes can be captured and exploited to guide proofs. As an instance of this scheme we present a quantified, metric, linear temporal logic containing processes and conjunctions of processes explicitly. Like a predicate a process can be regarded as a special kind of atomic formula with its own intension, a family of sets collecting the observable behavior as `runs\u27. A run is comparable with a Hoare-traces or a timed observational sequence it is a sequence of sequences of values taken from a set of objects. Each single value can be regarded as a snapshot of an observable feature at a moment in time, e.g. a value transmitted through a channel. Such a set has to respects the structure of the underlying temporal logic, but not one to one, we do not require that for a path in the time structure there is exactly one possible run. Since each run has a certain length, the view of a run is in particular associated with a time interval. The difference between moments and intervals of time is expressed by several kinds of modal operators each of them with restrictions in the shape of annotated equations and predicates to determined the relevant time slices. We describe syntax and semantic of this logic especially with a focus on the process part. Finally we sketch a calculus and give some examples

Breakup of Shearless Meanders and "Outer" Tori in the Standard Nontwist Map

The breakup of shearless invariant tori with winding number $\omega=[0,1,11,1,1,...]$ (in continued fraction representation) of the standard nontwist map is studied numerically using Greene's residue criterion. Tori of this winding number can assume the shape of meanders (folded-over invariant tori which are not graphs over the x-axis in $(x,y)$ phase space), whose breakup is the first point of focus here. Secondly, multiple shearless orbits of this winding number can exist, leading to a new type of breakup scenario. Results are discussed within the framework of the renormalization group for area-preserving maps. Regularity of the critical tori is also investigated.Comment: submitted to Chao

Minimal Recursion Semantics as Dominance Constraints: Translation, Evaluation, and Analysis

International audienceWe show that a practical translation of MRS descriptions into normal dominance constraints is feasible. We start from a recent theoretical translation, develop it into a practical system, and apply it to the output of the English Resource Grammar (ERG) on the Redwoods corpus. We validate the assumptions made by the theoretical translation for a large majority of cases; the MRS descriptions computed in all other cases seem to be systematically incomplete

On a new fixed point of the renormalization group operator for area-preserving maps

The breakup of the shearless invariant torus with winding number $\omega=\sqrt{2}-1$ is studied numerically using Greene's residue criterion in the standard nontwist map. The residue behavior and parameter scaling at the breakup suggests the existence of a new fixed point of the renormalization group operator (RGO) for area-preserving maps. The unstable eigenvalues of the RGO at this fixed point and the critical scaling exponents of the torus at breakup are computed.Comment: 4 pages, 5 figure

A Design Science Artefact for Cyber Threat Detection and Actor Specific Communication

Over the past few decades, the number and variety of cyberattacks and malware patterns have increased immensely. As a countermeasure, computer emergency response teams were established with the responsibility of securing the cyber environment. However, recent studies revealed that currently performed manual processes and the unavailability of adequate tools impede the achievement of cybersecurity. To address these challenges, we followed the Design Science paradigm to develop an artefact that improves the evaluation of open-source intelligence obtained from Twitter as well as the actor-specific communication of cyber threat information. Subsequently, the implemented artefact will be evaluated through semi-structured interviews with subject matter experts. This research in progress article presents the identified research gap and describes the development process and the endeavor to contribute to the cybersecurity domain theoretically with design principles for the development of an instrument and practically by implementing an artefact that supports domain experts in their work

Gauss map and Lyapunov exponents of interacting particles in a billiard

We show that the Lyapunov exponent (LE) of periodic orbits with Lebesgue measure zero from the Gauss map can be used to determine the main qualitative behavior of the LE of a Hamiltonian system. The Hamiltonian system is a one-dimensional box with two particles interacting via a Yukawa potential and does not possess Kolmogorov-Arnold-Moser (KAM) curves. In our case the Gauss map is applied to the mass ratio $\gamma = m_2/m_1$ between particles. Besides the main qualitative behavior, some unexpected peaks in the $\gamma$ dependence of the mean LE and the appearance of 'stickness' in phase space can also be understand via LE from the Gauss map. This shows a nice example of the relation between the "instability" of the continued fraction representation of a number with the stability of non-periodic curves (no KAM curves) from the physical model. Our results also confirm the intuition that pseudo-integrable systems with more complicated invariant surfaces of the flow (higher genus) should be more unstable under perturbation.Comment: 13 pages, 2 figure

What Measures Can Government Institutions in Germany Take Against Digital Disinformation? A Systematic Literature Review and Ethical-Legal Discussion

Disinformation campaigns spread rapidly through social media and can cause serious harm, especially in crisis situations, ranging from confusion about how to act to a loss of trust in government institutions. Therefore, the prevention of digital disinformation campaigns represents an important research topic. However, previous research in the field of information systems focused on the technical possibilities to detect and combat disinformation, while ethical and legal perspectives have been neglected so far. In this article, we synthesize previous information systems literature on disinformation prevention measures and discuss these measures from an ethical and legal perspective. We conclude by proposing questions for future research on the prevention of disinformation campaigns from an IS, ethical, and legal perspective. In doing so, we contribute to a balanced discussion on the prevention of digital disinformation campaigns that equally considers technical, ethical, and legal issues, and encourage increased interdisciplinary collaboration in future research

Scattering properties of a cut-circle billiard waveguide with two conical leads

We examine a two-dimensional electron waveguide with a cut-circle cavity and conical leads. By considering Wigner delay times and the Landauer-B\"{u}ttiker conductance for this system, we probe the effects of the closed billiard energy spectrum on scattering properties in the limit of weakly coupled leads. We investigate how lead placement and cavity shape affect these conductance and time delay spectra of the waveguide.Comment: 18 pages, 11 figures, accepted for publication in Phys. Rev. E (Jan. 2001