OpenRaiser/Intern-Atlas huggingface dataset:
Formative Assessment and its E-learning Implementation
Venue: arXiv cs.CY 2014
Year: 2014

Innovation in assessment is no more a choice in a tech-savvy instant age. The purpose of this study was to get more insight into the implementation of formative assessment through the e-learning tool called Black Board Learning System in our University. The proposal is to implement a series of weekly or fortnightly tests on the BB. These would have options to provide sufficient feedback as a follow up to the attempt of students. Responses from questionnaires were used to discover the important concerns in the perceptions of students on the proposed concept of continuous assessment and the BB Online test implementation. The results indicate that students support the idea mainly because they find the disintegration into small topic assessments as useful, coupled with the availability of immediate teacher feedback. What we intend is a culture of success, backed by a belief that all pupils can achieve the same.
Research status and trends in Operations Research and Management Science (OR/MS) journals: A bibliometric analysis based on the Web of Science database 2001-2012
Venue: arXiv cs.DL 2014
Year: 2014

A bibliometric analysis to evaluate global scientific production in the subject category of Operations Research and Management Science (OR/MS) from 2001 to 2012 was applied. Data was based on the Web of Science (Science Citation Index) database compiled by Thomson Reuters. The results showed that the OR/MS research has significantly increased over the past twelve years. The Bradford core journals in the category were identified. The researchers paid great attention to networks, control, and simulation. Among the countries, USA attained a dominant position in global research in the field.
Security - a perpetual war: lessons from nature
Venue: arXiv cs.CR 2014
Year: 2014

For ages people have sought inspiration in nature. Biomimicry has been the propelling power of such inventions, like Velcro tape or "cat's eyes" - retroreflective road marking. At the same time, scientists have been developing biologically inspired techniques: genetic algorithms, neural and sensor networks, etc. Although at a first glance there is no direct inspiration behind offensive and defensive techniques seen in the Internet and the patterns present in nature, closer inspection reveals many analogies between these two worlds. Botnets, DDoS (Distributed Denial of Service) attacks, IDS/IPSs (Intrusion Detection/Prevention Systems), and others, all employ strategies which very closely resemble actions undertaken by certain species of the kingdoms of living things. The main conclusion of the analysis is that security community should turn to nature in search of new offensive and defensive techniques for virtual world security.
Pruned Bit-Reversal Permutations: Mathematical Characterization, Fast Algorithms and Architectures
Venue: arXiv cs.IT 2014
Year: 2014

A mathematical characterization of serially-pruned permutations (SPPs) employed in variable-length permuters and their associated fast pruning algorithms and architectures are proposed. Permuters are used in many signal processing systems for shuffling data and in communication systems as an adjunct to coding for error correction. Typically only a small set of discrete permuter lengths are supported. Serial pruning is a simple technique to alter the length of a permutation to support a wider range of lengths, but results in a serial processing bottleneck. In this paper, parallelizing SPPs is formulated in terms of recursively computing sums involving integer floor and related functions using integer operations, in a fashion analogous to evaluating Dedekind sums. A mathematical treatment for bit-reversal permutations (BRPs) is presented, and closed-form expressions for BRP statistics are derived. It is shown that BRP sequences have weak correlation properties. A new statistic called permutation inliers that characterizes the pruning gap of pruned interleavers is proposed. Using this statistic, a recursive algorithm that computes the minimum inliers count of a pruned BR interleaver (PBRI) in logarithmic time complexity is presented. This algorithm enables parallelizing a serial PBRI algorithm by any desired parallelism factor by computing the pruning gap in lookahead rather than a serial fashion, resulting in significant reduction in interleaving latency and memory overhead. Extensions to 2-D block and stream interleavers, as well as applications to pruned fast Fourier transforms and LTE turbo interleavers, are also presented. Moreover, hardware-efficient architectures for the proposed algorithms are developed. Simulation results demonstrate 3 to 4 orders of magnitude improvement in interleaving time compared to existing approaches.
Transforming while/do/for/foreach-Loops into Recursive Methods
Venue: arXiv cs.PL 2014
Year: 2014

In software engineering, taking a good election between recursion and iteration is essential because their efficiency and maintenance are different. In fact, developers often need to transform iteration into recursion (e.g., in debugging, to decompose the call graph into iterations); thus, it is quite surprising that there does not exist a public transformation from loops to recursion that handles all kinds of loops. This article describes a transformation able to transform iterative loops into equivalent recursive methods. The transformation is described for the programming language Java, but it is general enough as to be adapted to many other languages that allow iteration and recursion. We describe the changes needed to transform loops of types while/do/for/foreach into recursion. Each kind of loop requires a particular treatment that is described and exemplified.
Unshared Secret Key Cryptography
Venue: arXiv cs.CR 2014
Year: 2014

Current security techniques can be implemented with either secret key exchange or physical layer wiretap codes. In this work, we investigate an alternative solution for MIMO wiretap channels. Inspired by the artificial noise (AN) technique, we propose the unshared secret key (USK) cryptosystem, where the AN is redesigned as a one-time pad secret key aligned within the null space between transmitter and legitimate receiver. The proposed USK cryptosystem is a new physical layer cryptographic scheme, obtained by combining traditional network layer cryptography and physical layer security. Unlike previously studied artificial noise techniques, rather than ensuring non-zero secrecy capacity, the USK is valid for an infinite lattice input alphabet and guarantees Shannon's ideal secrecy and perfect secrecy, without the need of secret key exchange. We then show how ideal secrecy can be obtained for finite lattice constellations with an arbitrarily small outage.
Improved Region-Growing and Combinatorial Algorithms for $k$-Route Cut Problems
Venue: arXiv cs.DS 2014
Year: 2014

We study the {\em $k$-route} generalizations of various cut problems, the most general of which is \emph{$k$-route multicut} ($k$-MC) problem, wherein we have $r$ source-sink pairs and the goal is to delete a minimum-cost set of edges to reduce the edge-connectivity of every source-sink pair to below $k$. The $k$-route extensions of multiway cut ($k$-MWC), and the minimum $s$-$t$ cut problem ($k$-$(s,t)$-cut), are similarly defined. We present various approximation and hardness results for these $k$-route cut problems that improve the state-of-the-art for these problems in several cases. (i) For {\em $k$-route multiway cut}, we devise simple, but surprisingly effective, combinatorial algorithms that yield bicriteria approximation guarantees that markedly improve upon the previous-best guarantees. (ii) For {\em $k$-route multicut}, we design algorithms that improve upon the previous-best approximation factors by roughly an $O(\sqrt{\log r})$-factor, when $k=2$, and for general $k$ and unit costs and any fixed violation of the connectivity threshold $k$. The main technical innovation is the definition of a new, powerful \emph{region growing} lemma that allows us to perform region-growing in a recursive fashion even though the LP solution yields a {\em different metric} for each source-sink pair. (iii) We complement these results by showing that the {\em $k$-route $s$-$t$ cut} problem is at least as hard to approximate as the {\em densest-$k$-subgraph} (DkS) problem on uniform hypergraphs.
Fixed-Points of Social Choice: An Axiomatic Approach to Network Communities
Venue: arXiv cs.SI 2014
Year: 2014

We provide the first social choice theory approach to the question of what constitutes a community in a social network. Inspired by the classic preferences models in social choice theory, we start from an abstract social network framework, called preference networks; these consist of a finite set of members where each member has a total-ranking preference of all members in the set. Within this framework, we develop two complementary approaches to axiomatically study the formation and structures of communities. (1) We apply social choice theory and define communities indirectly by postulating that they are fixed points of a preference aggregation function obeying certain desirable axioms. (2) We directly postulate desirable axioms for communities without reference to preference aggregation, leading to eight natural community axioms. These approaches allow us to formulate and analyze community rules. We prove a taxonomy theorem that provides a structural characterization of the family of community rules that satisfies all eight axioms. The structure is actually quite beautiful: these community rules form a bounded lattice under the natural intersection and union operations. Our structural theorem is complemented with a complexity result: while identifying a community by the most selective rule of the lattice is in P, deciding if a subset is a community by the most comprehensive rule of the lattice is coNP-complete. Our studies also shed light on the limitations of defining community rules solely based on preference aggregation: any aggregation function satisfying Arrow's IIA axiom, or based on commonly used aggregation schemes like the Borda count or generalizations thereof, lead to communities which violate at least one of our community axioms. Finally, we give a polynomial-time rule consistent with seven axioms and weakly satisfying the eighth axiom.
Finding Near-optimal Solutions in Multi-robot Path Planning
Venue: arXiv cs.RO 2014
Year: 2014

We deal with the problem of planning collision-free trajectories for robots operating in a shared space. Given the start and destination position for each of the robots, the task is to find trajectories for all robots that reach their destinations with minimum total cost such that the robots will not collide when following the found trajectories. Our approach starts from individually optimal trajectory for each robot, which are then penalized for being in collision with other robots. The penalty is gradually increased and the individual trajectories are iteratively replanned to account for the increased penalty until a collision-free solution is found. Using extensive experimental evaluation, we find that such a penalty method constructs trajectories with near-optimal cost on the instances where the optimum is known and otherwise with 4-10 % lower cost than the trajectories generated by prioritized planning and up to 40 % cheaper than trajectories generated by local collision avoidance techniques, such as ORCA.
On Content-centric Wireless Delivery Networks
Venue: arXiv cs.NI 2014
Year: 2014

The flux of social media and the convenience of mobile connectivity has created a mobile data phenomenon that is expected to overwhelm the mobile cellular networks in the foreseeable future. Despite the advent of 4G/LTE, the growth rate of wireless data has far exceeded the capacity increase of the mobile networks. A fundamentally new design paradigm is required to tackle the ever-growing wireless data challenge. In this article, we investigate the problem of massive content delivery over wireless networks and present a systematic view on content-centric network design and its underlying challenges. Towards this end, we first review some of the recent advancements in Information Centric Networking (ICN) which provides the basis on how media contents can be labeled, distributed, and placed across the networks. We then formulate the content delivery task into a content rate maximization problem over a share wireless channel, which, contrasting the conventional wisdom that attempts to increase the bit-rate of a unicast system, maximizes the content delivery capability with a fixed amount of wireless resources. This conceptually simple change enables us to exploit the "content diversity" and the "network diversity" by leveraging the abundant computation sources (through application-layer encoding, pushing and caching, etc.) within the existing wireless networks. A network architecture that enables wireless network crowdsourcing for content delivery is then described, followed by an exemplary campus wireless network that encompasses the above concepts.
Computationally -Efficient Algorithms for Multiuser Detection in Short Code Wideband CDMA (TDD) Systems
Venue: arXiv cs.IT 2014
Year: 2014

Paper derives and analyzes a novel block Fast Fourier Transform (FFT) based joint detection algorithm. The paper compares the performance and complexity of the novel block-FFT based joint detector to that of the Cholesky based joint detector and single user detection algorithms. The novel algorithm can operate at chip rate sampling, as well as higher sampling rates, unlike existing algorithms. For the performance/complexity analysis, the time division duplex (TDD) mode of a wideband code division multiplex access (WCDMA) is considered. The results indicate that the performance of the fast FFT based joint detector is comparable to that of the Cholesky based joint detector, and much superior to that of single user detection algorithms. On the other hand, the complexity of the fast FFT based joint detector is significantly lower than that of the Cholesky based joint detector and less than that of the single user detection algorithms. For the Cholesky based joint detector, the approximate Cholesky decomposition is applied. Moreover, the novel method can also be applied to any generic multiple-input-multiple-output (MIMO) system.
Optimized Disk Layouts for Adaptive Storage of Interaction Graphs
Venue: arXiv cs.DB 2014
Year: 2014

We are living in an ever more connected world, where data recording the interactions between people, software systems, and the physical world is becoming increasingly prevalent. This data often takes the form of a temporally evolving graph, where entities are the vertices and the interactions between them are the edges. We call such graphs interaction graphs. Various application domains, including telecommunications, transportation, and social media, depend on analytics performed on interaction graphs. The ability to efficiently support historical analysis over interaction graphs require effective solutions for the problem of data layout on disk. This paper presents an adaptive disk layout called the railway layout for optimizing disk block storage for interaction graphs. The key idea is to divide blocks into one or more sub-blocks, where each sub-block contains a subset of the attributes, but the entire graph structure is replicated within each sub-block. This improves query I/O, at the cost of increased storage overhead. We introduce optimal ILP formulations for partitioning disk blocks into sub-blocks with overlapping and non-overlapping attributes. Additionally, we present greedy heuristic approaches that can scale better compared to the ILP alternatives, yet achieve close to optimal query I/O. To demonstrate the benefits of the railway layout, we provide an extensive experimental study comparing our approach to a few baseline alternatives.
3D Printing: Developing Countries Perspectives
Venue: arXiv cs.CY 2014
Year: 2014

For the past decade, 3D printing (3DP) has become popular due to availability of low-cost 3D printers such as RepRap and Fab@Home; and better software, which offers a broad range of manufacturing platform that enables users to create customizable products. 3DP offers everybody with the power to convert a digital design into a three dimensional physical object. While the application of 3DP in developing countries is still at an early stage, the technology application promises vast solutions to existing problems. This paper presents a critical review of the current state of art of 3DP with a particular focus on developing countries. Moreover, it discusses the challenges, opportunities and future insights of 3DP in developing countries. This paper will serve as a basis for discussion and further research on this area.
Neural Turing Machines
Venue: arXiv cs.NE 2014
Year: 2014

We extend the capabilities of neural networks by coupling them to external memory resources, which they can interact with by attentional processes. The combined system is analogous to a Turing Machine or Von Neumann architecture but is differentiable end-to-end, allowing it to be efficiently trained with gradient descent. Preliminary results demonstrate that Neural Turing Machines can infer simple algorithms such as copying, sorting, and associative recall from input and output examples.
Software in e-Learning Architecture, Processes and Management
Venue: arXiv cs.SE 2014
Year: 2014

Our entire society is becoming more and more dependent on technology and specifically on software. The integration of e-learning software systems into our day by day life especially in e-learning applications generates modifications upon the society and, at the same time, the society itself changes the process of software development. This circle of continuous determination engenders a highly dynamic environment. Lehman describes the software development environment as being characterized by a high, necessary and inevitable pressure for change. Changes are reflected in specific uncertainties which impact the success and performance of the software project development.
Certified Connection Tableaux Proofs for HOL Light and TPTP
Venue: arXiv cs.LO 2014
Year: 2014

In the recent years, the Metis prover based on ordered paramodulation and model elimination has replaced the earlier built-in methods for general-purpose proof automation in HOL4 and Isabelle/HOL. In the annual CASC competition, the leanCoP system based on connection tableaux has however performed better than Metis. In this paper we show how the leanCoP's core algorithm can be implemented inside HOLLight. leanCoP's flagship feature, namely its minimalistic core, results in a very simple proof system. This plays a crucial role in extending the MESON proof reconstruction mechanism to connection tableaux proofs, providing an implementation of leanCoP that certifies its proofs. We discuss the differences between our direct implementation using an explicit Prolog stack, to the continuation passing implementation of MESON present in HOLLight and compare their performance on all core HOLLight goals. The resulting prover can be also used as a general purpose TPTP prover. We compare its performance against the resolution based Metis on TPTP and other interesting datasets.
On computational complexity of length embeddability of graphs
Venue: arXiv cs.CC 2014
Year: 2014

A graph $G$ is embeddable in $\mathbb{R}^d$ if vertices of $G$ can be assigned with points of $\mathbb{R}^d$ in such a way that all pairs of adjacent vertices are at the distance 1. We show that verifying embeddability of a given graph in $\mathbb{R}^d$ is NP-hard in the case $d > 2$ for all reasonable notions of embeddability.
Variance-Constrained Capacity of the Molecular Timing Channel with Synchronization Error
Venue: arXiv cs.IT 2014
Year: 2014

Molecular communication is set to play an important role in the design of complex biological and chemical systems. An important class of molecular communication systems is based on the timing channel, where information is encoded in the delay of the transmitted molecule---a synchronous approach. At present, a widely used modeling assumption is the perfect synchronization between the transmitter and the receiver. Unfortunately, this assumption is unlikely to hold in most practical molecular systems. To remedy this, we introduce a clock into the model---leading to the molecular timing channel with synchronization error. To quantify the behavior of this new system, we derive upper and lower bounds on the variance-constrained capacity, which we view as the step between the mean-delay and the peak-delay constrained capacity. By numerically evaluating our bounds, we obtain a key practical insight: the drift velocity of the clock links does not need to be significantly larger than the drift velocity of the information link, in order to achieve the variance-constrained capacity with perfect synchronization.
Dynamic Optimization For Heterogeneous Powered Wireless Multimedia Sensor Networks With Correlated Sources and Network Coding
Venue: arXiv cs.NI 2014
Year: 2014

The energy consumption in wireless multimedia sensor networks (WMSN) is much greater than that in traditional wireless sensor networks. Thus, it is a huge challenge to remain the perpetual operation for WMSN. In this paper, we propose a new heterogeneous energy supply model for WMSN through the coexistence of renewable energy and electricity grid. We address to cross-layer optimization for the multiple multicast with distributed source coding and intra-session network coding in heterogeneous powered wireless multimedia sensor networks (HPWMSN) with correlated sources. The aim is to achieve the optimal reconstruct distortion at sinks and the minimal cost of purchasing electricity from electricity grid. Based on the Lyapunov drift-plus-penalty with perturbation technique and dual decomposition technique, we propose a fully distributed dynamic cross-layer algorithm, including multicast routing, source rate control, network coding, session scheduling and energy management, only requiring knowledge of the instantaneous system state. The explicit trade-off between the optimization objective and queue backlog is theoretically proven. Finally, the simulation results verify the theoretic claims.
Robust Multidimensional Mean-Payoff Games are Undecidable
Venue: arXiv cs.LO 2014
Year: 2014

Mean-payoff games play a central role in quantitative synthesis and verification. In a single-dimensional game a weight is assigned to every transition and the objective of the protagonist is to assure a non-negative limit-average weight. In the multidimensional setting, a weight vector is assigned to every transition and the objective of the protagonist is to satisfy a boolean condition over the limit-average weight of each dimension, e.g., $\LimAvg(x_1) \leq 0 \vee \LimAvg(x_2)\geq 0 \wedge \LimAvg(x_3) \geq 0$. We recently proved that when one of the players is restricted to finite-memory strategies then the decidability of determining the winner is inter-reducible with Hilbert's Tenth problem over rationals (a fundamental long-standing open problem). In this work we allow arbitrary (infinite-memory) strategies for both players and we show that the problem is undecidable.