An intruder model for verifying termination in security protocols

We formally describe an intruder that is suitable for checking fairness properties of security protocols. The intruder is proved to be equivalent to the Dolev-Yao intruder that respects the resilient communication channels assumption, in the sense that, if a fairness property holds in one of these models, it also holds in the other

Fast kk-NNG construction with GPU-based quick multi-select

In this paper we describe a new brute force algorithm for building the $k$-Nearest Neighbor Graph ($k$-NNG). The $k$-NNG algorithm has many applications in areas such as machine learning, bio-informatics, and clustering analysis. While there are very efficient algorithms for data of low dimensions, for high dimensional data the brute force search is the best algorithm. There are two main parts to the algorithm: the first part is finding the distances between the input vectors which may be formulated as a matrix multiplication problem. The second is the selection of the $k$-NNs for each of the query vectors. For the second part, we describe a novel graphics processing unit (GPU) -based multi-select algorithm based on quick sort. Our optimization makes clever use of warp voting functions available on the latest GPUs along with use-controlled cache. Benchmarks show significant improvement over state-of-the-art implementations of the $k$-NN search on GPUs

IS KUWAIT TV DIGLOSSIC? A SOCIOLINGUISTIC INVESTIGATION

Diglossia is a sociolinguistic term refers to the use of two varieties of one language in a given community; one is regarded as the high variety and the other as a low variety. This paper is a qualitative study thatinvestigates diglossia in various Kuwaiti TV stations. It attempts to mainly see if the two varieties are used differently whenever there is a change of topic in TV programs. Topics investigated include news, programs discussing political issues, cooking, sports, religion, and fashion. The researchers made sure that all programs chosen for investigation are presented by Kuwaitis. Data collected for this study relied mainly on observations and videotaping which took five months duration. Data was then phonetically transcribed and qualitatively analyzed.Speech extracts indicating the use of either H or L variety are demonstrated where necessary. The analysis showed that diglossia extensively exists in all the Kuwaiti TVchannels under investigation. Such a study may, to some extent, draw some generalizations about diglossia in Kuwait due to the fact that these channels present a variety of diglossic behaviors in different settings by different Kuwaiti speakers

Access Control Synthesis for Physical Spaces

Access-control requirements for physical spaces, like office buildings and airports, are best formulated from a global viewpoint in terms of system-wide requirements. For example, "there is an authorized path to exit the building from every room." In contrast, individual access-control components, such as doors and turnstiles, can only enforce local policies, specifying when the component may open. In practice, the gap between the system-wide, global requirements and the many local policies is bridged manually, which is tedious, error-prone, and scales poorly. We propose a framework to automatically synthesize local access control policies from a set of global requirements for physical spaces. Our framework consists of an expressive language to specify both global requirements and physical spaces, and an algorithm for synthesizing local, attribute-based policies from the global specification. We empirically demonstrate the framework's effectiveness on three substantial case studies. The studies demonstrate that access control synthesis is practical even for complex physical spaces, such as airports, with many interrelated security requirements

Competing Universalities in Kardar-Parisi-Zhang (KPZ) Growth Models

We report on the universality of height fluctuations at the crossing point of two interacting (1+1)-dimensional Kardar-Parisi-Zhang (KPZ) interfaces with curved and flat initial conditions. We introduce a control parameter p as the probability for the initially flat geometry to be chosen and compute the phase diagram as a function of p. We find that the distribution of the fluctuations converges to the Gaussian orthogonal ensemble Tracy-Widom (TW) distribution for p0.5. For p=0.5 where the two geometries are equally weighted, the behavior is governed by an emergent Gaussian statistics in the universality class of Brownian motion. We propose a phenomenological theory to explain our findings and discuss possible applications in nonequilibrium transport and traffic flow.Comment: 5 pages, 6 figures, Phys. Rev. Lett. (2019) (accepted

Probing charge and heat current noise by frequency-dependent temperature and potential fluctuations

The energetic properties of electron transport in mesoscopic and nanoscale conductors is of large current interest. Here we theoretically investigate the possibility of probing fluctuations of charge and heat currents as well as their mixed correlations via fluctuations of the temperature and electrochemical potential of a probe coupled to the conductor. Our particular interest is devoted to the charge and energy noise stemming from time-dependently driven nanoelectronic systems designed for the controlled emission of single electrons, even though our setup is appropriate for more general AC driving schemes. We employ a Boltzmann-Langevin approach in order to relate the frequency-dependent electrochemical potential and temperature fluctuations in the probe to the bare charge and energy current fluctuations emitted from the electron source. We apply our findings to the prominent example of an on-demand single-electron source, realized by a driven mesoscopic capacitor in the quantum Hall regime. We show that neither the background fluctuations of the probe in the absence of the working source, nor the fluctuations induced by the probe hinder the access to the sought-for direct source noise for a large range of parameters.Comment: 17 pages, 6 figures, in revie