34739655
On the Bisimulation Congruence in chi-Calculus
In this paper, we study weak bisimulation congruences for the χ-calculus, a symmetric variant of the π-calculus. We distinguish two styles of such bisimulation definitions, i.e. “open” and “closed” bisimulation, the difference between which lies in that in open style the equivalence is closed under context in every bisimulation step whereas in closed style the equivalence is closed under context only at the very beginning. As a result, we show that both in labelled and barbed congruence, the open and closed style definitions coincide. Thus all bisimulation congruences collapse into two equivalences, that is, the well-known open congruence and open barbed congruence, which are the same in the strong case, while in the weak case their difference can be reflected by one axiom. The results of this paper close some conjectures in the literatures and shed light on the algebraic theory of a large class of mobile process calculi.
8043922
Intensionality of modal logic for Robust Ambient Calculus
Abstract Computation with mobility becomes a novel distributed computation paradigm with the development of network technology. The calculus of Mobile Ambient is a widely studied formal mechanism for describing both mobile computing and mobile computation. To improve this process calculus, Robust Mobile Ambient is introduced by providing co-actions. This paper deals with the modal logic for finite fragment of this calculus without communication primitives. In details, we compare standard behavioral equivalence with the equivalence induced by the logic (=L) and with the structural congruence. As a result, we prove the intensionality of the logic and at the same time, an axiomatization for = L is given. The authors thank the three referees for many constructive suggestions and comments.
17432425
Structure analysis for dynamic software architecture
The open and dynamic Internet environment greatly urges software entities that are distributed on different locations to coordinate with each other to accomplish a computing task. Software architecture is applied to abstract the software entities to be components and the coordination between them to be connectors and then a model is extracted as the architecture on which the design, analysis and verification are based. Currently, the notion of dynamic software architectures that can modify their architecture and enact modifications during the system execution has become one of the most active research areas. In this paper, we focus on the dynamic evolution of system structure other than coordination mechanisms (e.g. communication protocols). It is widely recognized that some restrictions should be imposed on the system evolution to ensure that the system structure may remain one style or transform within a scope. These conditions, to a large extent, make the system execute under control as expected.
5970126
On the Complete Axiomatization for Prefix Iteration modulo Observation Congruence
Prefix iteration is a variation on the original binary version of the Kleene star operation P*Q, obtained by restricting the first argument to be an atomic action. Aceto and Ingolfsdottir provided an axiom system for observation congruence over basic CCS with prefix iteration. However hitherto the only direct completeness proof given for such a system is very long and technical. In this paper, we provide a new proof for the completeness of the axiom system in [3], which is a considerable simplification comparing to the original proof. Thus the open problem to find a direct completeness proof is closed.
8665982
Structure analysis for dynamic software architecture based on spatial logic
The requirement for modifying system structure during system execution is specified by dynamic software architectures. The system architecture style should remain one style or transform within a scope so that some constraints need to be imposed on during the system execution. Our work expands such an idea along two directions in the setting of formalism. The first direction is to model the system by a graph-based calculus stressing the structure. The other direction lies in that we tailor spatial logic to be a suitable logic as the system specification for structure. The model and specification are basis for the model checking algorithm that is to verify whether the system evolution satisfies some structure constraints. We invite a master-slave architecture style as a running example from the beginning and throughout the paper to demonstrate our approach. Such work can be seen as the basis of the structure analysis for architectures.
5876317
Framework of performance evaluation for mobile process based on mobile ambient
Formal methodology for distributed and concurrent system, especially computation system with mobility, is increasingly important both in the theory and the practice. Based on the calculus of mobile ambient (MA), a widely studied formal mechanism for mobile computation, this paper focuses on the quantitative analysis of mobile computation system and provides a framework of performance evaluation for it. In details, this paper introduces an enhanced labelled transition system as the system model, and assigns rate to each label through so-called cost function. Based on it, the labelled transition system can be mapped to continuous time Markov chains and thus performance evaluation can be carried out by standard numerical techniques and tools. In some sense the main work of this paper can be regarded as integrating behavior and performance analysis in a compositional formal framework, which provides some basis of unified formal methodology for the development of mobile system.
305291
Toward an Efficient Column Minimum Degree Code for Symmetric Multiprocessors
Ordering the columns of a nonsymmetric sparse matrix can reduce the fill created in its factorization. Minimum-degree is a popular heuristic for ordering symmetric matrices; a variant that can be used to order nonsymmetric matrices is called column minimum degree. In this paper we describe the design of a multithreaded approximate column minimum degree code. We present a framework for the algorithm, study potential sources of parallel inefficiency, and describe our attempts to circumvent the obstacles. We present experimental results that support our analysis.
19799763
An approach to isochronous slot reuse for multimedia services on DQDB network
This paper discusses an isochronous connection management protocol and its slot-reuse scheme for multimedia services on DQDB network. For asynchronous services, slot-reuse improves slot utilization, which has already been discussed in depth. However only few literature addressed the slot-reuse for synchronous services. Our proposed scheme reuses video slots for either synchronous or asynchronous services according to the need of downstream nodes. Simulation shows that the scheme significantly increases the maximum number of video connections as well as reduces the failure rate of connection request comparing with that without slot-reuse.
18209709
Mesostructure from Specularity
We describe a simple and robust method for surface mesostructure acquisition. Our method builds on the observation that specular reflection is a reliable visual cue for surface mesostructure perception. In contrast to most photometric stereo methods, which take specularities as outliers and discard them, we propose a progressive acquisition system that captures a dense specularity field as the only information for mesostructure reconstruction. Our method can efficiently recover surfaces with fine-scale geometric details from complex real-world objects with a wide variety of reflection properties, including translucent, low albedo, and highly specular objects. We show results for a variety of objects including human skin, dried apricot, orange, jelly candy, black leather and dark chocolate.
33188963
Improving the quality of classification trees via restructuring
The classification-hierarchy table developed by Chen and Poon (1996) provides a systematic approach to construct classification trees from given sets of classifications and their associated classes. The paper enhances their study by defining a metric to measure the "quality" of a classification tree, and providing an algorithm to improve this quality.
18749157
A case study in genome-level fragment assembly
MOTIVATION
We use the fact of two teams independently sequencing the one megabase genome of Borrelia burgdorferi as an opportunity to study the accuracy of genome-level assembly.


RESULTS
We compare the results of three different assembly programs (PHRAP, TIGR Assembler, and STROLL) on the DNA fragments used in both the Brookhaven and TIGR sequencing projects. We also describe the algorithms and data structures used in our assembly program STROLL, which was used in the Brookhaven Borrelia project.