Distinguishing Views in Symmetric Networks: A Tight Lower Bound

The view of a node in a port-labeled network is an infinite tree encoding all walks in the network originating from this node. We prove that for any integers $n\geq D\geq 1$, there exists a port-labeled network with at most $n$ nodes and diameter at most $D$ which contains a pair of nodes whose (infinite) views are different, but whose views truncated to depth $\Omega(D\log (n/D))$ are identical

Topology recognition with advice

In topology recognition, each node of an anonymous network has to deterministically produce an isomorphic copy of the underlying graph, with all ports correctly marked. This task is usually unfeasible without any a priori information. Such information can be provided to nodes as advice. An oracle knowing the network can give a (possibly different) string of bits to each node, and all nodes must reconstruct the network using this advice, after a given number of rounds of communication. During each round each node can exchange arbitrary messages with all its neighbors and perform arbitrary local computations. The time of completing topology recognition is the number of rounds it takes, and the size of advice is the maximum length of a string given to nodes. We investigate tradeoffs between the time in which topology recognition is accomplished and the minimum size of advice that has to be given to nodes. We provide upper and lower bounds on the minimum size of advice that is sufficient to perform topology recognition in a given time, in the class of all graphs of size $n$ and diameter $D\le \alpha n$, for any constant $\alpha< 1$. In most cases, our bounds are asymptotically tight

On the Algorithmic Power of Spiking Neural Networks

Spiking Neural Networks (SNN) are mathematical models in neuroscience to describe the dynamics among a set of neurons that interact with each other by firing instantaneous signals, a.k.a., spikes. Interestingly, a recent advance in neuroscience [Barrett-Den\`eve-Machens, NIPS 2013] showed that the neurons' firing rate, i.e., the average number of spikes fired per unit of time, can be characterized by the optimal solution of a quadratic program defined by the parameters of the dynamics. This indicated that SNN potentially has the computational power to solve non-trivial quadratic programs. However, the results were justified empirically without rigorous analysis. We put this into the context of natural algorithms and aim to investigate the algorithmic power of SNN. Especially, we emphasize on giving rigorous asymptotic analysis on the performance of SNN in solving optimization problems. To enforce a theoretical study, we first identify a simplified SNN model that is tractable for analysis. Next, we confirm the empirical observation in the work of Barrett et al. by giving an upper bound on the convergence rate of SNN in solving the quadratic program. Further, we observe that in the case where there are infinitely many optimal solutions, SNN tends to converge to the one with smaller l1 norm. We give an affirmative answer to our finding by showing that SNN can solve the l1 minimization problem under some regular conditions. Our main technical insight is a dual view of the SNN dynamics, under which SNN can be viewed as a new natural primal-dual algorithm for the l1 minimization problem. We believe that the dual view is of independent interest and may potentially find interesting interpretation in neuroscience.Comment: To appear in ITCS 201

Archival Romances : Found, Compressed and Loved Again

Images have a life cycle that is material, social, and imaginative. Their trajectories are especially evident in the work of Arab media artists. Like others in places where official image archives are difficult to access, value glitch, error, and loss of resolution not only for their own aesthetic interest but also as indications of the labor of love required to access the past. Analog demagnetization and lossy digital compression; glitch, error, and artifacts introduced by compression; and layers of formatting draw attention to the trajectories and life cycles of images. Rania Stephan, Mohammad Allam, Riad Yassin, Roy Dib, and other Arab media artists painstakingly amass VHS collections of popular movies and TV shows, in archives that augment in care while they diminish in quality. Other artists including Akram Zaatari, Sophia Al-Maria, and Joana Hadjithomas and Khalil Joreige draw attention to the new meanings that attach to anonymous images as they travel online, finally to be embraced by the recipient

Fold-thrust structures : where have all the buckles gone?

Special publication title: Folding and Fracturing of Rocks: 50 Years of Research since the Seminal Text Book of J. G. Ramsay We dedicate the paper to the memory of Martin Casey (1948-2008), who did much through good-humored argument to ensure that buckling ideas were not lost to what he called “the Ramping Club” (the thrust belt community). The Fold – Thrust Research Group has been funded by InterOil, OilSearch and Santos. We thank Paul Griffiths and anonymous referee for comments together with Hermann Lebit for scientific editing. The views expressed here of course remain those of the authors.Peer reviewedPostprin

La construcción por estratos. Técnicas y estrategias del proyecto moderno (1923-1945)

The influence of industrialization on architecture in the first half of 20th century changed architects’ way of working, who resorted to industrialized products to create an architecture characterized by Construction by Strata. New strategies were put into practice and the role of technique became something more than simply resorting to new materials or advanced industrialized technology. The aesthetic component became an inherent aspect of the building itself and was always subtly present to reflect the consistency with which the objective criteria of scientific methods were used. The main objective of this research is, using the case method, to analyze, from a technical and constructive point of view, the new project strategies that emerged at the beginning of the 20&nbsp;th&nbsp; century from the appearance of new paradigms, as well as to demonstrate the creative capacities of the construction process itself and check the current validity of the identified strategies.La influencia de la industrialización en la arquitectura de la primera mitad del siglo 20 modificó el modo de trabajar de los arquitectos, quienes recurrieron a productos industrializados para crear una arquitectura caracterizada por la Construcción por Estratos. Nuevas estrategias se pusieron en práctica y el rol de la técnica se convirtió en algo más que un simple recurso a nuevos materiales o tecnologías industrializadas avanzadas. El componente estético se convirtió en un aspecto inherente al propio edificio y siempre estuvo sutilmente presente para reflejar la coherencia con la que se utilizaron los criterios objetivos propios del método científico. El principal objetivo de esta investigación es, utilizando el método del caso, analizar, desde un punto de vista técnico-constructivo, las nuevas estrategias de proyecto surgidas a principios del sigo XX a partir de la aparición de nuevos paradigmas, así como demostrar las capacidades creativas del propio proceso de construcción y verificar la vigencia de las estrategias identificadas

Distributed multimedia systems

A distributed multimedia system (DMS) is an integrated communication, computing, and information system that enables the processing, management, delivery, and presentation of synchronized multimedia information with quality-of-service guarantees. Multimedia information may include discrete media data, such as text, data, and images, and continuous media data, such as video and audio. Such a system enhances human communications by exploiting both visual and aural senses and provides the ultimate flexibility in work and entertainment, allowing one to collaborate with remote participants, view movies on demand, access on-line digital libraries from the desktop, and so forth. In this paper, we present a technical survey of a DMS. We give an overview of distributed multimedia systems, examine the fundamental concept of digital media, identify the applications, and survey the important enabling technologies.published_or_final_versio