18279993
Mixed Preservation of Conditionally Nonblocking Switches under 2-stage Interconnection
The 2-stage interconnection network is conceivably the most compact design for interconnecting small switches into a large switch. When a certain class of switches is preserved under 2-stage interconnection, recursive application of 2-stage interconnection then builds indefinitely large switches in this class from atomic ones. The present paper studies switches that are not preserved under 2-stage interconnection but are yet constructive from atomic elements through recursive 2-stage interconnection. The principle is "mixed preservation" based on the following two properties: first, the 2-stage interconnection network constructs a class-A switch when switches at nodes on one stage belong to class A and switches at nodes on the other stage belong to class B; second, class-B switches are preserved under 2-stage interconnection. A class of conditionally nonblocking switches for such mixed preservation are identified, which are useful in the recursive construction of distribution networks
45808479
Recursive Construction of Distributors by Merging
39573562
Binary Trees and Uniform Distribution of Traffic Cutback
Abstract This article introduces the notion of the External Left Length (ELL) of binary trees, which is analogous to the notion of the External Path Length (EPL), and derives theorems about the ELL which correspond to well-known facts about the EPL. Results are applied to the analysis of the optimization of an algorithm for the smooth traffic cutback in data communication.
2426410
Network information flow
We introduce a new class of problems called network information flow which is inspired by computer network applications. Consider a point-to-point communication network on which a number of information sources are to be multicast to certain sets of destinations. We assume that the information sources are mutually independent. The problem is to characterize the admissible coding rate region. This model subsumes all previously studied models along the same line. We study the problem with one information source, and we have obtained a simple characterization of the admissible coding rate region. Our result can be regarded as the max-flow min-cut theorem for network information flow. Contrary to one's intuition, our work reveals that it is in general not optimal to regard the information to be multicast as a "fluid" which can simply be routed or replicated. Rather, by employing coding at the nodes, which we refer to as network coding, bandwidth can in general be saved. This finding may have significant impact on future design of switching systems.
15838609
Linear network coding
Consider a communication network in which certain source nodes multicast information to other nodes on the network in the multihop fashion where every node can pass on any of its received data to others. We are interested in how fast each node can receive the complete information, or equivalently, what the information rate arriving at each node is. Allowing a node to encode its received data before passing it on, the question involves optimization of the multicast mechanisms at the nodes. Among the simplest coding schemes is linear coding, which regards a block of data as a vector over a certain base field and allows a node to apply a linear transformation to a vector before passing it on. We formulate this multicast problem and prove that linear coding suffices to achieve the optimum, which is the max-flow from the source to each receiving node.
206817675
Independence numbers of graphs and generators of ideals
This article investigates the generators of certain homogeneous ideals which are associated with graphs with bounded independence numbers. These ideals first appeared in the theory oft-designs. The main theorem suggests a new approach to the Clique Problem which isNP-complete. This theorem has a more general form in commutative algebra dealing with ideals associated with unions of linear varieties. This general theorem is stated in the article; a corollary to it generalizes Turán’s theorem on the maximum graphs with a prescribed clique number.
13799673
A Metric-Based Heuristic Framework to Detect Object-Oriented Design Flaws
One of the important activities in re-engineering process is detecting design flaws. Such design flaws prevent an efficient maintenance, and further development of a system. This research proposes a novel metric-based heuristic framework to detect and locate object-oriented design flaws from the source code. It is accomplished by evaluating design quality of an object-oriented system through quantifying deviations from good design heuristics and principles. While design flaws can occur at any level, the proposed approach assesses the design quality of internal and external structure of a system at the class level which is the most fundamental level of a system. In a nutshell, design flaws are detected and located systematically in two phases using a generic OO design knowledge-base. In the first phase, hotspots are detected by primitive classifiers via measuring metrics indicating a design feature (e.g. complexity). In the second phase, individual design flaws are detected by composite classifiers using a proper set of metrics. We have chosen JBoss application server as the case study, due to its pure OO large size structure, and its success as an open source J2EE platform among developers
16413633
Feature analysis for service-oriented reengineering
Web services together with service-oriented architectures (SOA) are playing an important role in the future of distributed computing, significantly impacting software development and evolution. With the adoption to Web services technology, more and more existing non-service-oriented software systems turn to be legacy systems. They require a service-oriented reengineering process in order to survive in service-oriented computing environment. If the reengineering goal is to expose the services of a single object or any underlying function-oriented middleware, many problems will arise including semantic mismatches, service granularity issues and state management. Attempting to masquerade software assets from a lower level of abstraction can often cause significant mismatch and exposure problems. In this paper, by using feature analysis, an approach to supporting service-oriented reengineering is presented. Service identification and packaging process are performed and resulted into a service delegation.
8736073
Using Feature-Oriented Analysis to Recover Legacy Software Design for Software Evolution
Most design recovery approaches start from analysing source code. Nonetheless, it is very difficult to get adequate design information only depending on source code. Additional available information is required and Feature Oriented Analysis (FOA) is a way to reach this aim. FOA addresses the understanding of features in software systems and defines mechanisms for carrying a feature from the problem domain into the solution domain. Using feature as the first-class entity for software evolution can improve program comprehension and design recovery. In this paper, an approach is proposed to recover software design based on the feature model, which is a kind of legacy system knowledge. The features will first be located and mapped to the implementation module so that feature-oriented components can be identified and retrieved, and then, through the analysis of the feature relations, the design model of legacy system can be recovered and used for the future evolution.
36253673
A fuzzy goal programming approach to multi-objective optimization problem with priorities
Abstract In goal programming problem, the general equilibrium and optimization are often two conflicting factors. This paper proposes a generalized varying-domain optimization method for fuzzy goal programming (FGP) incorporating multiple priorities. According to the three possible styles of the objective function, the varying-domain optimization method and its generalization are proposed. This method can generate the results consistent with the decision-maker (DM)’s expectation, that the goal with higher priority may have higher level of satisfaction. Using this new method, it is a simple process to balance between the equilibrium and optimization, and the result is the consequence of a synthetic decision between them. In contrast to the previous method, the proposed method can make that the higher priority achieving the higher satisfactory degree. To get the global solution of the nonlinear nonconvex programming problem resulting from the original problem and the varying-domain optimization method, the co-evolutionary genetic algorithms (GAs), called GENOCOPIII, is used instead of the SQP method. In this way the DM can get the optimum of the optimization problem. We demonstrate the power of this proposed method by illustrative examples.
18473631
Cryptanalysis of a Chaotic Neural Network Based Multimedia Encryption Scheme
Recently, Yen and Guo proposed a chaotic neural network (CNN) for signal encryption, which was suggested as a solution for protection of digital images and videos. The present paper evaluates the security of this CNN-based encryption scheme, and points out that it is not secure from the cryptographical point of view: 1) it can be easily broken by known/chosen-plaintext attacks; 2) its security against the brute-force attack was much over-estimated. Some experiments are shown to support the results given in this paper. It is also discussed how to improve the encryption scheme.