waashk/dblp huggingface dataset:
the synergy of precise and fast abstractions for program verification. predicate abstraction is a powerful technique to reduce the state space of a program to a finite and affordable number of states. it produces a conservative over-approximation where concrete states are grouped together according to a given set of predicates. a precise abstraction contains the minimal set of transitions with regards to the predicates, but as a result is computationally expensive. most model checkers therefore approximate the abstraction to alleviate the computation of the abstract system by trading off precision with cost. however, approximation results in a higher number of refinement iterations, since it can produce more false counterexamples than its precise counterpart. the refinement loop can become prohibitively expensive for large programs. this paper proposes a new abstraction refinement technique that combines slow and precise predicate abstraction techniques with fast and imprecise ones. it allows computing the abstraction quickly, but keeps it precise enough to avoid too many refinement iterations. we implemented the new algorithm in a state-of-the-art software model checker. our tests with various real life benchmarks show that the new approach systematically outperforms both precise and imprecise techniques.
on scheduling soft real-time tasks with lock-free synchronization for embedded devices. in this paper, we consider minimizing the system-level energy consumption through dynamic voltage scaling for embedded devices, while a) allowing concurrent access to shared objects through lock-free synchronization b) meeting (m, k))-constraint, and c) completing as many high importance tasks as possible. we present a scheduling algorithm called lock-free utility accrual algorithm (or mk-lfua) to meet these goals. at offline stage, we set the optimal cpu speed to minimize system-level energy consumption. at run-time, the algorithm dynamically adjusts the cpu speed to compensate for slack time. our simulation studies on the intel pxa271 processor model illustrate mk-lfua's superiority over past work by 15-25%.
supporting recovery, privacy and security in rfid systems using a robust authentication protocol. rfid systems have been scrutinized nowadays as one of the emerging technologies in pervasive environment. and authentication becomes indispensible in applications where security and privacy are major concerns. besides thwarting some major attacks, rfid systems need to be able to recover from unexpected conditions during operation. in this paper, we propose a robust authentication protocol (roap) that supports not only security and privacy, but also recovery in rfid systems. the protocol can get back the desynchronized tags and readers to their normal state, and thus provides robustness. we also present a "safety ring" consisted of six major goals that have to ensure by each rfid system to be secured. this paper illustrates security and robustness analysis of the protocol. finally, we present the implementation of our authentication protocol.
incorporating accountability into internet email. email used to be the "number one killer application" of the internet. however, misuse and abuse such as spam, phishing, and malware attacks have plagued the email systems. considering deterrence as important as prevention and protection in countering misuse and abuse, we aim to improve the accountability in the email system beyond identification and non-repudiability. full accountability should be an intrinsic condition for trust, and it constitutes the basis of deterrence against email misuse and abuse. therefore, we propose to use a layered trust management framework to help email receivers eliminate their unwitting trust and provide them with accountability support. this helps systems to deter misuses and address wrongdoings. by describing and analyzing how our trust management facilitates email accountability, we also show that it can be used to improve the trustworthiness of the internet services as a whole.
using artificial life techniques for distributed grid job scheduling. grids are an emerging infrastructure providing distributed access to computational and storage resources. handling many incoming requests at the same time and distributing the workload efficiently is a challenge which load balancing algorithms address. current load balancing implementations for the grid are central in nature and therefore prone to the single point of failure problem. this paper introduces two distributed artificial life-inspired load balancing algorithms using ant colony optimization and particle swarm optimization. distributed load balancing stands out as a robust algorithm in regard to any topology changes in the network. the implementation details are given and evaluation results show the efficiency of the two distributed load balancing algorithms.
visual loop-closing with image profiles. this paper investigates the ability of image profiles, pixel-intensity sums across subsets of a video stream, to support the crucial robotic skill of place recognition through visual information alone. building from work in which image profiles are the fundamental image representation for a model of biological neural processing [3, 4, 5], this paper offers a conceptually simpler approach to simultaneous localization and mapping via a single camera (monocular slam). in contrast to feature-based approaches in which extraction and statistical post-processing dominate the computation, this work uses a representation suitable even for very simple autonomous platforms. experiments demonstrate the ability of our profile-based path segments to compensate for the inevitable inaccuracies in odometry when creating consistent world maps.
simplifying security policy descriptions for internet servers in secure operating systems. secure operating systems (secure oses) are widely used to limit the damage caused by unauthorized access to internet servers. however, writing a security policy based on the principle of least privilege for a secure os is a challenge for an administrator. considering that remote attackers can never attack a server before they establish connections to it, we propose a novel scheme that exploits phases to simplify security policy descriptions for internet servers. in our scheme, the entire system has two execution phases: an initialization phase and a protocol processing phase. the initialization phase is defined as the phase before the server establishes connections to its clients, and the protocol processing phase is defined as the phase after it establishes connections. the key observation is that access control should be enforced by the secure os only in the protocol processing phase to defend against remote attacks. thus, we can omit the access-control policy in the initialization phase, which effectively reduces the number of policy rules. our experimental results demonstrate that our scheme effectively reduces the number of descriptions; it eliminates 47.2%, 27.5%, and 24.0% of policy rules for http, smtp, and pop servers respectively, compared with an existing selinux policy that includes the initialization of the server.
tweast: a simple and effective technique to implement concrete-syntax ast rewriting using partial parsing. abstract syntax trees (asts) are commonly used to represent an input/output program in compilers and language processing tools. many of the tasks of these tools consist in generating and rewriting asts. such an approach can become tedious and hard to maintain for complex operations, namely program transformation, optimization, instrumentation, etc. on the other hand, concrete syntax provides a natural and simpler representation of programs, but it is not usually available as a direct feature of the aforementioned tools. we propose a simple technique to implement ast generation and rewriting in general purpose languages using concrete syntax. our approach relies on extensions made in the scanner and the parser and the use of objects supporting partial parsing called texts with embedded abstract syntax trees (tweasts). a compiler for a simple language (tiger) written in c++ serves as an example, featuring transformations in concrete syntax: syntactic desugaring, optimization, code instrumentation such as bounds-checking, etc. extensions of this technique to provide a full-fledged concrete-syntax rewriting framework are presented as well.
itrustu: a blog recommender system based on multi-faceted trust and collaborative filtering. blogs give users a channel to express their knowledge and feelings with individuals worldwide, explaining the exponential growth of new blogs. however, due to the diverse subjects covered by bloggers, bloggers/readers have difficulty in finding valuable articles from the hundreds of millions of blogs on the internet. to help ease information overload in the blogosphere, this work proposes a trust-enhanced collaborative filtering approach that integrates multi-faceted trust based on article type and user similarity. an online blog article recommender system, called itrustu, is also designed to evaluate the effectiveness of the proposed approach in terms of accuracy and quality of recommendations. results of a 45-day online experiment with 179 participants from the internet demonstrate that the proposed integrated approach yields a significantly higher accuracy than traditional approaches, especially for cold-start users. analysis results indicate that trust and similarity among bloggers/readers have a significantly positive correlation in the blogosphere. effective recommender systems can be achieved by exploiting trust relationships in a trust network. the proposed approach is applicable not only to the blogosphere, but also to online social communities when trust relationships already exist between users.
the unique solution for problem. in this paper, we make the study on the unique solution for the p3p problem. after partitioning the space into several regions, the parametric function and target function for each region are presented. under the condition of knowing the approximate relative position between center of perspective and control points, the unique solution can be obtained.
abstraction of multiple executions of object-oriented programs. recovering software behaviors from execution traces is useful in program comprehension and maintenance. multiple executions upon different test inputs can help to locate program behaviors related to a particular use case, i.e. a specific functionality. an abstraction and visualization environment abstracer was developed, and experiments have been performed on an open-source software, jhotdraw.
semi-automatic parallelization of direct and inverse problems for geothermal simulation. we describe a strategy for parallelizing a geothermal simulation package using the shared-memory programming model openmp. during the code development openmp is employed for the direct problem in such a way that, in a subsequent step, the openmp-parallelized code can be transformed via automatic differentiation into an openmp-parallelized code capable of computing derivatives for the inverse problem. performance results on a sun fire x4600 using up to 16 threads are reported demonstrating that, for the derivative computation, an approach using nested parallelism is more scalable than a single level of parallelism.
global-to-local representation and visualization of molecular surfaces using deformable models. macromolecules such as proteins and enzymes are responsible for most of cellular functionality. many molecular interactions, such as protein-protein interactions or protein-ligand binding, occur at what can be defined as the molecular surface. the topology of the molecular surface is often complex, containing various geometric features such as clefts, cavities, tunnels, and flat regions. these geometric features coupled with non-geometric physicochemical properties influence surface-based molecular interactions. consequently analysis of molecular surfaces is crucial in elucidating structure-property relationships of molecules. in this paper we propose a method for visualizing a molecular surface in a manner that preserves and elucidates salient features. the method involves mapping of a molecular surface to a standard spherical coordinate system. the ability to map arbitrary molecular surfaces to a standard coordinate system aids in comparison of surface features across different molecules. the mapping is accomplished by enclosing the molecular surface by a sphere, and then iteratively deforming the sphere until it converges by wrapping the entire molecular surface. this allows a one-to-one relationship to be established between points on the molecular surface and points on the surface of the sphere. the presence of discontinuities such as tunnels in the molecular surface can be identified by detecting collision between patches of the deforming sphere. subsequently, the deformable surface is restored back to the sphere, retaining the mapping. features and properties defined at the molecular surface are then mapped and visualized in the standard spherical coordinate system. the proposed approach has several key advantages. first, it allows a global-to-local visualization of molecular surfaces. second, it facilitates comparison of specific features as well as collection of features within and across molecules by mapping them to a common coordinate system. third, the method allows visualization of both geometric and non-geometric surface properties. fourth, specific molecular characteristics can be visualized individually or in combination on-demand. finally, and crucially the advantages offered by the proposed visualization do not involve simplification of the surface characteristics thereby ensuring that no loss of potentially important information occurs.
spam decisions on gray e-mail using personalized ontologies. e-mail is one of the most common communication methods among people on the internet. however, the increase of e-mail misuse/abuse has resulted in an increasing volume of spam e-mail over recent years. as spammers always try to find a way to evade existing spam filters, new filters need to be developed to catch spam. a statistical learning filter is at the core of many commercial anti-spam filters. it can either be trained globally for all users, or personally for each user. generally, globally-trained filters outperform personally-trained filters for both small and large collections of users under a real environment. however, globally-trained filters sometimes ignore personal data. globally-trained filters cannot retain personal preferences and contexts as to whether a feature should be treated as an indicator of legitimate e-mail or spam. gray e-mail is a message that could reasonably be considered either legitimate or spam. in this paper, a personalized ontology spam filter was implemented to make decisions for gray e-mail. in the future, by considering both global and personal ontology-based filters, we can show a significant improvement in overall performance.
stratified division queries involving ordinal user preferences. in this paper, we are interested in taking preferences into account for a family of queries inspired by the relational division. a division query aims at retrieving the elements associated with a specified set of values and usually the results remain not discriminated. so, we suggest the introduction of preferences inside such queries with the following specificities: i) the user gives his/her preferences in an ordinal way and ii) the preferences apply to the divisor which is defined as a hierarchy of sets. different uses of the hierarchy are investigated, which leads to queries conveying different semantics and the property of the result in terms of a quotient is studied. a special attention is paid to the implementation of such queries using a regular database management system and some experimental results illustrate the feasibility of the approach.
new content-aware request distribution policies in web clusters providing multiple services. due to the explosive growth of the internet and increasing service demands from all around the world, the cluster-based system that consists of one request-dispatching server and several request-handling servers has become a cost-effective way to serve the huge amount of service demands. nowadays, web servers have to handle more complex types of requests since requests from clients may be mixed with dynamic web pages, database processing, or multimedia stream data. therefore, a web cluster should be designed with intelligent request dispatching policies for supporting various types of service requests. in this paper, we have proposed two new content-aware request distribution policies named locality-aware request distribution with replication and classification (lard/rc) and grouped client-aware policy (gcap) to dispatch requests efficiently in web clusters providing multiple types of services and running in homogeneous or heterogeneous environments. we have implemented our proposed policies in the lvs-cad web cluster that can efficiently perform content-aware request dispatching. performance evaluation shows that our proposed lard/rc and gcap policies could dispatch requests of different types to proper back-end servers in a more efficient way to utilize system resources than the other existing policies in both homogeneous and heterogeneous environments.
visual navigation: image profiles for odometry and control. this paper investigates the extent to which image profiles, pixel-intensity sums across subsets of a video stream, offer a basis for autonomous robotics. building on previous work that uses image profiles for odometry, we introduce an improved algorithm for odometric estimation based on visual input alone. in addition, we extend prior results by showing how image profiles can support control and exploration tasks. we validate these new approaches through results implemented atop a low-cost vision-only vehicle consisting of a laptop and an irobot create.
robust scheduler for grid networks. imprecise input data imposes additional challenges to grid scheduling. this paper introduces a novel scheduler based on fuzzy optimization called ip-full-fuzzy which considers uncertainties of both application demands and of resource availability. the effectiveness of the proposed scheduler is compared to those of a non-fuzzy scheduler as well as to those of a fuzzy scheduler which considers only uncertainties of application demands. results evince the advantages of adopting the proposed scheduler.
facial image classification of mouse embryos for the animal model study of fetal alcohol syndrome. fetal alcohol syndrome (fas) is a developmental disorder caused by maternal drinking during pregnancy. computerize imaging techniques have been applied to study human facial dysmorphology associated with fas. this paper describes a new facial image analysis method based on a multi-angle image classification technique using micro-video images of mouse embryo. images taken from several different angles are analyzed separately, and the results are combined for classifications that separate embryos with and without alcohol exposures. analysis results from animal models provide critical references for the understanding of fas and potential therapy solutions for human patients.
an extensible simulation tool for overlay networks and services. research community on distributed systems, and in particular on peer-to-peer systems, needs tools for evaluating their own protocols and services, as well as against other protocols with the same preconditions. since a (tcp/ip) experimental evaluation is not always feasible, simulation tools appeared. in this paper we introduce planetsim, a discrete event-based simulation framework tool for overlay networks and services, as well as extensions from third parties that prove its true extensibility and adaptability to the researchers' needs. in addition, we introduce within planetsim a novel methodology for implementing peer-to-peer overlay protocols based on behaviors.
online annotation and prediction for regime switching data streams. regime switching models, in which the state of the world is locally stationary, are a useful abstraction for many continuous valued data streams. in this paper we develop an online framework for the challenging problem of jointly predicting and annotating streaming data as it arrives. the framework consists of three sequential modules: prediction, change detection and regime annotation, each of which may be instantiated in a number of ways. we describe a specific realisation of this framework with the prediction module implemented using recursive least squares, and change detection implemented using cusum techniques. the annotation step involves associating a label with each regime, implemented here using a confidence interval approach. experiments with simulated data show that this methodology can provide an annotation that is consistent with ground truth. finally, the method is illustrated with foreign exchange data.
geographical data collection in sensor networks with self-organizing transaction cluster-heads. this paper proposes 2g, a flexible and energy-efficient data collection protocol for sensor networks for increasing network lifetime. to this end, it integrates self-organizing data aggregation mechanisms based on geographical and cluster-based routing, and transaction cluster-head (tch). a tch is a location-based role, dynamically assigned to a node for the duration of handling a request-response transaction that targets its region of the network. tch nodes collect raw sensor readings from their local regions and forward the answers containing aggregated data using geographical routing. a prototype of 2g was implemented on micaz motes, and experimental results in realistic conditions proved that data collection reaches significantly higher delivery rates than with gear, the geographical routing protocol leveraged by 2g. additionally, simulation results for larger scale networks demonstrate that 2g outperforms gear in terms of network lifetime.
representing refactoring opportunities. approaches for the representation of refactoring opportunities and their association with refactorings are usually described in an informal basis. this informality can hamper the creation of catalogues and tools to represent and search for refactoring opportunities. we propose an unified way to represent both the conditions in which the application of a refactoring can be advantageous and the mechanisms to associate these conditions with refactorings. the resulting representation mechanisms can be used to express search criteria based on software metrics, structural problems, heuristics or improvements on the software quality.
data parallel dialect of scheme: outline of the formal model, implementation, performance. we outline new functional programming language and stack-based model of implicit parallel execution of programs. the language, called schemik, is high-level lexically-scoped implicitly-parallel dialect of scheme. schemik is designed as an implicitly parallel language, meaning that the parallel execution of programs is done independently of the programmer and each program written in schemik always produces the same results no matter which parts of the program are executed simultaneously. the execution of programs is formally described by transitions of a particular pushdown automaton working with two stacks. because of the limited scope of this paper, we just outline key ideas and postpone detailed description to a full version of this paper.