14954145
Interacting frameworks in Catalysis
In current OO design, most of the existing (semi-formal) methods use classes or objects as the basic unit of design. However it is increasingly recognised that classes are not the best focus for design. Typical design artefacts are about groups of objects and the way they interact In the Catalysis project, we use the term frameworks for descriptions of groups of objects, their relationships, division of responsibilities, and interactions. The power of frameworks lies in the fact that interactions can also occur at the level of frameworks. In a previous paper we defined a framework formally as a (first-order) many-sorted theory with a model theoretic semantics and showed how it can be represented using a pictorial notation for practical system development. However we considered only frameworks that do not interact with one another In this paper we discuss frameworks that interact with one another and show that such frameworks are very powerful tools for formal OO design.
9811887
A formal operational semantics for SOFL
SOFL (Structured-Object-Based-Formal Language) is a formal language and method for practical systems development. As a language, it integrates data flow diagrams, VDM-SL, and Petri nets to provide a graphical and textual formal notation for specification construction. Previous publications introducing SOFL are based on its informal semantics. We provide a formal operational semantics which gives a firm foundation for consistent understanding and application of SOFL in practical systems development. Development of the semantics, and application of SOFL to practical systems, have led to some changes in the original definitions. This formal semantics will serve as a firm foundation for building an effective support environment for SOFL.
6009818
A Formal Definition of FRSM and Applications
FRSM (Formal Requirements Specification Method) is a structured formal language and method for requirements analysis and specification construction based on data flow analysis. It uses a formalized DeMarco data flow diagram to describe the overall structure of systems and a VDM-SL like formal notation to describe precisely the functionality of components in the diagrams. This paper first describes the formal syntax and semantics of FRSM and then presents an example of using the axiom and inference rules given in the definition of the formal semantics for checking consistency of specifications. A case study of applying FRSM to a practical example is described to demonstrate the principle of constructing requirements specifications and to uncover the benefits and deficiencies of FRSM.
30881235
Criteria for generating specification-based tests
This paper presents general criteria for generating test inputs from state-based specifications. Software testing can only be formalized and quantified when a solid basis for test generation can be defined. Formal specifications of complex systems represent a significant opportunity for testing because they precisely describe what functions the software is supposed to provide in a form that can easily be manipulated. These techniques provide coverage criteria that are based on the specifications, and are made up of several parts, including test prefixes that contain inputs necessary to put the software into the appropriate state for the test values. The test generation process includes several steps for transforming specifications to tests. Empirical results from a comparative case study application of these criteria are presented.
1976770
Self-independent Petri Nets for Distributed Systems
We propose that asynchronous mechanism for communication should be considered as a primitive for semantic models of distributed systems in contrast to the synchronous mechanism (hand-shaking) of CSP (Hoare, 1985) and of CCS (Milner, 1989). By doing so, we present an approach to producing a deadlock-free system, and give a denotational model for CCS in a non-interleaving fashion.
1315911
An Object Semantic Model of SOFL
SOFL (Structured-Object-based-Formal Language) is recently proposed to combine the advantages of formal methods, structured methods and object-oriented methodology into one method for software development. SOFL integrates modeling techniques from VDM (for specifying system component state) and data flow diagrams with Petri nets (for specifying system behaviours and interaction). To support the standardisation and the tool support for SOFL, a formal semantics of the language is desirable. As SOFL is under further development, the semantic representation of current SOFL needs to be easily reused and extended. In this paper, an object-oriented approach is taken to specify the semantics of SOFL and this approach is proved to be effective in providing a modular and reusable semantic representation. Object modeling techniques, such as inheritance is used to illustrate the common and the differences between various SOFL graphical constructs; object containment is used to capture the acyclic structure of SOFL hierarchical module decomposition.
14314870
Formalization, Testing and Execution of a Use Case Diagram
Errors in a requirements model have prolonged detrimental effects on reliability, cost, and safety of a software system. It is very costly to fix these errors in later phases of software development if they cannot be corrected during requirements analysis and design. A use case diagram, as a requirements model, plays an important role in giving requirements for a software system. It provides a communication tool between software requirements developers and prospective users to understand what requirements of a software system are. However most descriptions of a use case diagram are written in some informal language, leading to possible misunderstanding between developers and users. In this paper, we propose a new rigorous review technique which can be applied to software requirements models. Using this new technique before a software system is fully designed will help us find some potential errors in a requirements model, resulting in reduced time, labor and expenditure in software development.
6979172
Encoding the Temporal Statistics of Markovian Sequences of Stimuli in Recurrent Neuronal Networks
Encoding, storing, and recalling a temporal sequence of stimuli in a neuronal network can be achieved by creating associations between pairs of stimuli that are contiguous in time. This idea is illustrated by studying the behavior of a neural network model with binary neurons and binary stochastic synapses. The network extracts in an unsupervised manner the temporal statistics of the sequence of input stimuli. When a stimulus triggers the recalling process, the statistics of the output patterns reflects those of the input. If the sequence of stimuli is generated through a Markov process, then the network dynamics faithfully reproduces all the transition probabilities.
14849633
A study of Japanese software process practices and a potential for improvement using SOFL
The goal of this paper is to examine the Japanese experience with the software development process, the challenges they face and how formal engineering methods, in particular SOFL (structured object-oriented formal language), can help overcome these problems. We also recommend additional management tools and documents that can aid organizations in achieving a higher CMM rating through the use of SOFL.
719681
Feature competition in a spike-based winner-take-all VLSI network
Recurrent networks and hardware analogs that perform a winner-take-all computation have been studied extensively. This computation is rarely demonstrated in a spiking network of neurons receiving input spike trains. In this work, we demonstrate this computation not only within a VLSI network but also across networks of integrate-and-fire neurons in a feature competition task. The chip has four populations of neurons receiving input spike trains that represent the outputs of four feature maps. The connectivity within each population is configured so that all the neurons compete with one another. In addition, a second level of competition, which we call the feature competition, can be introduced between all populations (or feature maps). The two levels of competition are useful in a system that has to select both the locations of relevant features and the best feature map that is coded in an input stimulus. The selection process can be completed as fast as after two input spikes
14446563
Vague Content and Structure (VCAS) Retrieval for Document-centric XML Collections
document-centric XML collections with structure conditions improves retrieval precisions. The structures of such XML collections, however, are often too complex for users to fully grasp. Thus, for queries regarding such collections, it is more appropriate to retrieve answers that approximately match the structure and content conditions in these queries, a process also known as vague content and structure (VCAS) retrieval. Most existing XML engines, however, only support content-only (CO) retrieval and/or strict content and structure (SCAS) retrieval. To remedy these shortcomings, we propose an approach for VCAS retrieval using existing XML engines. Our approach first decomposes a VCAS query into a SCAS sub-query and a CO sub- query, then uses existing XML engines to retrieve SCAS results and CO results for the decomposed sub-queries, and finally combines results from both retrievals to produce approximate results for the original query. Further, to improve retrieval precision, we propose two similarity metrics to adjust the scores of CO retrieval results by their relevancies to the path condition for the original query target. We evaluate our VCAS retrieval approach through extensive experiments with the INEX 04 XML collection and VCAS query sets. The experimental results demonstrate the effectiveness of our VCAS retrieval approach.