1233277
A delay-optimal quorum-based mutual exclusion scheme with fault-tolerance capability
The performance of a mutual exclusion algorithm is measured by the number of messages exchanged per critical section execution and the delay between successive executions of the critical section. There is a message complexity and synchronization delay trade-off in mutual exclusion algorithms. Lamport's (1978) algorithm and Ricart and Agrawal's (1981) algorithm both have a synchronization delay of T, but their message complexity is O(N). Maekawa's (1985) algorithm reduces message complexity to O(/spl radic/N); however, it increases the synchronization delay to 2T. After Maekawa's algorithm, many quorum-based mutual exclusion algorithms have been proposed to reduce message complexity or increase the resiliency to site and communication link failures. Since these algorithms are Maekawa-type algorithms, they also suffer from long synchronization delay 2T. We propose a delay-optimal quorum-based mutual exclusion algorithm which reduces the synchronization delay to T and still has the low message complexity O(K) (K is the size of the quorum, which can be as low as log N). A correctness proof and detailed performance analysis are provided.
26263616
Developing a Formal Design Analysis Framework
9746543
Design an Interoperable Mobile Agent System Based on Predicate Transition Net Models
Mobile agents provide an effective and flexible style to develop advanced distributed systems. In order to promote interoperability and ensure the quality of mobile agent systems, it is necessary to formalize software architecture of mobile agent systems. In this paper, we not only define the software architecture of interoperable mobile agent systems using predicate transition nets, but also analyze the interoperability between agents. In addition, a formal model-driven design method to develop mobile agent systems is described with examples. Our method naturally integrates formal methods and practical approaches in the agent system design phase. The method can be used to develop other complex software systems as well.
24822225
Achieving a Better Middleware Design through Formal Modeling and Analysis
13531819
A visual approach to XML document design and transformation
This paper presents a visual approach to the representation and validation of multimedia document structures specified in XML and transformation of one structure to another. The underlying theory of our approach is a context-sensitive graph grammar formalism. The paper demonstrates the conciseness and expressiveness of the graph grammar formalism. An example XML structure is provided and its graph grammar representation, validation and transformation to a multimedia representation are presented.
14596334
A formal approach to designing secure software architectures
Software architecture plays a central role in developing software systems that provide basic functionality and satisfy critical properties such as reliability and security. However, little has been done to formally model software architectures and to systematically enforce required properties. We aim to propose a formal approach to designing secure software architectures. We use the software architecture model (SAM), a general software architecture model combining Petri nets and temporal logic, as the underlying formalism. Architecture design consists of the functionality part and the security part. Guidelines are proposed to design functionality of software architectures at both element level and composition level. Software security is enforced by stepwise refinement.
23293268
Novel Ω-protocols for NP
AbstractΩ-protocols, introduced by Garay, Mackenzie and Yang, is a variant of S-protocols with online extractor which is a useful tool to overcome the nest effect in concurrent scenario. In this work, we construct an Ω-protocol for Hamiltonian cycle problem, and therefore, it allows us to present Ω-protocol for any NP relation. For most general NP relations, our construction of Ω-protocols is much more efficient than the informal one described by Garay et al. and we believe that the method for our construction may be of independent interest.
2501651
A Fast Line Segment Based Dense Stereo Algorithm Using Tree Dynamic Programming
Many traditional stereo correspondence methods emphasized on utilizing epipolar constraint and ignored the information embedded in inter-epipolar lines. Actually some researchers have already proposed several grid-based algorithms for fully utilizing information embodied in both intra- and inter-epipolar lines. Though their performances are greatly improved, they are very time-consuming. The new graph-cut and believe-propagation methods have made the grid-based algorithms more efficient, but time-consuming still remains a hard problem for many applications. Recently, a tree dynamic programming algorithm is proposed. Though the computation speed is much higher than that of grid-based methods, the performance is degraded apparently. We think that the problem stems from the pixel-based tree construction. Many edges in the original grid are forced to be cut out, and much information embedded in these edges is thus lost. In this paper, a novel line segment based stereo correspondence algorithm using tree dynamic programming (LSTDP) is presented. Each epipolar line of the reference image is segmented into segments first, and a tree is then constructed with these line segments as its vertexes. The tree dynamic programming is adopted to compute the correspondence of each line segment. By using line segments as the vertexes instead of pixels, the connection between neighboring pixels within the same region can be reserved as completely as possible. Experimental results show that our algorithm can obtain comparable performance with state-of-the-art algorithms but is much more time-efficient.
1960949
A symmetric patch-based correspondence model for occlusion handling
Occlusion is one of the challenging problems in stereo. In this paper, we solve the problem in a segment-based style. Both images are segmented, and we propose a novel patch-based stereo algorithm that cuts the segments of one image using the segments of the other, and handles occlusion areas in a proper way. A symmetric graph-cuts optimization framework is used to find correspondence and occlusions simultaneously. The experimental results show superior performance of the proposed algorithm, especially on occlusions, untextured areas and discontinuities
42696276
Concurrently Non-malleable Black-Box Zero Knowledge in the Bare Public-Key Model
In this paper we study the possibility of reducing the setup assumptions under which concurrent non-malleable zero knowledge protocol can be realized. A natural model choice is the bare public-key (BPK) model of [6], a model with very minimal setup assumptions. Our main contribution is to show in this model the following about constant-round concurrent non-malleable black-box zero-knowledge arguments. 
They can be constructed from any one-way function for any language in $\mathcal{NP}$. Here, our construction takes 5 rounds, and we can reduce it to a 4-round (round-optimal) argument under existence of one-way permutations. 
Under number-theoretic assumptions, they admit a time-efficient instantiation for some specific $\mathcal{NP}$ languages (e.g., all languages having efficient Σ protocols, for which we can implement our construction using only $\mathcal{O}(1)$ modular exponentiations). 
 
 
 
Compared to the non-black-box construction in a concurrent work of [OPV, ICALP 2008] in this model, our protocol (even the construction from one-way function) is significantly more time- and round-efficient and can be based on more general assumptions.
207130140
Guest Editors' Introduction: Special Issue on Embedded Software Engineering
Embedded systems, typically components of larger electro-mechanical systems with the purpose of controlling or helping such systems to achieve their overall goals, are playing an increasingly critical role in modern society and economy. According to David Tennenhouse, Chief Scientist of Intel and former director of DARPA ISO, 98% of all current computer applications are embedded systems. The market for embedded computer applications has shown explosive growth with tremendous applications in, for example, telecommunications, health-care, manufacturing, remote monitoring, and transportation, to name a few. An important trend is that embedded systems are becoming increasingly complex, software-intensive and distributed. For instance, it was projected that software written for cellular phones will reach from 2 to 5 million lines of code in the next few years. While this underscores the growing importance of software it also raises some concerns since methods of developing embedded software are lagging far behind hardware advances. The unique characteristics of embedded systems, such as complex control logic, severe limitations on resources (e.g. memory and power consumption), hard real-time constraints, and stringent performance and dependability requirements, are stressing the limits of mainstream architectures, languages, tools, and techniques. Much of the embedded software development today depends on intensive manual programming and costly yet error-prone testing methods for quality assurance. Further, current embedded software development techniques use monolithic designs which are not scalable, configurable, or adaptable. These problems have resulted in long product cycles, cost overruns, and poor system quality. These problems, if not addressed, will escalate, and significantly hinder the development and deployment of complex embedded systems. This special issue on embedded software engineering is aimed at stimulating research interests in this important emerging area, which merges software engineering methodologies and techniques with embedded system development techniques. After careful reviews, five papers were selected for the special issue. Collectively,