5683523
A Metadata Approach to Resolving Semantic Conflicts
In this paper we describe a rule-based approach to semantic specification that can be used to establish semantic agreement between a source and receiver. Query processing techniques use these specifications along with conversion routines and query modification to guarantee correct data semantics. This work also examines the effect of changing data semantics. These changes may occur at the source of the data or they may be changes in the specifications of the dat,a semantics for the application, Methods are described for detecting these changes and for determining if the database can continue to supply meaningful data to the application. These methods for semanlic reconcilia2ion are necessary for determining logical connectivity between a data source (database) and a data receiver (application). Though described in terms of the source-receiver model, these techniques can also be used for semantic reconciliation and schema integration for multidatabase systems. Keywords[data dictionaries, heterogeneous databases, metadata, query modification, schema integration, semantic conflicts]
38159603
The COntext INterchange (COIN) Project: Data Extraction and Interpretation from Semi-Structured Web Sources
2677077
Context interchange: new features and formalisms for the intelligent integration of information
The Context Interchange strategy presents a novel perspective for mediated data access in which semantic conflicts among heterogeneous systems are not identified a priori, but are detected and reconciled by a context mediator through comparison of contexts axioms corresponding to the systems engaged in data exchange. In this article, we show that queries formulated on shared views, export schema, and shared “ontologies” can be mediated in the same way using the Context Interchange framework. The proposed framework provides a logic-based object-oriented formalsim for representing and reasoning about data semantics in disparate systems, and has been validated in a prototype implementation providing mediated data access to both traditional and web-based information sources.
3110757
Context Knowledge Representation and Reasoning in the Context Interchange System
The Context Interchange Project presents a unique approach to the problem of semantic conflict resolution among multiple heterogeneous data sources. The system presents a semantically meaningful view of the data to the receivers (e.g. user applications) for all the available data sources. The semantic conflicts are automatically detected and reconciled by a Context Mediator using the context knowledge associated with both the data sources and the data receivers. The results are collated and presented in the receiver context. The current implementation of the system provides access to flat files, classical relational databases, on-line databases, and web services. An example application, using actual financial information sources, is described along with a detailed description of the operation of the system for an example query.
523278
Seizing the Opportunity: Exploiting Web Aggregation
This paper examines the development of web aggregators, entities that collect information from a wide range of sources, with or without prior arrangements, and add value through post-aggregation services. New Web-page extraction tools, context sensitive mediators, and agent technologies have greatly reduced the barriers to constructing aggregators. We predict that aggregators will soon emerge in industries where they were not formerly present. Through studying over a hundred existing and emerging aggregators, we present a model for understanding the aggregator's strategic interaction with existing organizations. We also suggest different ways that businesses can take advantage of the new opportunities presented. Finally, we provide valuable insights to all organizations concerning the issues, impacts, and actions required as aggregators become increasingly present.
17058444
The Context Interchange Network Prototype
In this paper we describe a prototype implementation of the Context Interchange Network (CIN). The prototype is described in terms of a financial application. The CIN is designed to provide for the intelligent integration of contextually (i.e., semantically) heterogeneous data. The system uses explicit context knowledge representation and a context mediator to automatically detect conflicts and resolve them through context conversion. The network also allows for context explication; making it possible for a receiver of data to understand meaning of the information represented by the source data.
37254437
Exact Solutions for the Evolution of a Bubble in Stokes Flow: A Cauchy Transform Approach
A Cauchy transform approach to the problem of determining the free surface evolution of a single bubble in Stokes flow is developed. A number of exact solutions to a class of problems have been derived in the literature using conformal mapping theory, and these solutions are retrieved and further generalized using the new formulation. Certain quantities which are conserved by the dynamics are also identified, the existence of which had not previously been pointed out. A principal purpose of this paper is to use the new formulation to understand when it is possible to externally specify the evolution of the bubble area in such classes of exact solution. It is found to be possible only for certain types of far-field boundary conditions.
15882359
Deciding Equality Formulas by Small Domains Instantiations
We introduce an efficient decision procedure for the theory of equality based on finite instantiations. When using the finite instantiations method, it is a common practice to take a range of [1..n] (where n is the number of input non-Boolean variables) as the range for all non-Boolean variables, resulting in a state-space of nn. Although various attempts to minimize this range were made, typically they either required various restrictions on the investigated formulas or were not very effective. In many cases, the nn state-space cannot be handled by BDD-based tools within a reasonable amount of time. In this paper we show that significantly smaller domains can be algorithmically found, by analyzing the structure of the formula. We also show an upper bound for the state-space based on this analysis. This method enabled us to verify formulas containing hundreds of integer and floating point variables.
7986917
Translation Validation: From DC+ to C*
Translation validation is an alternative to the verification of translators (compilers, code generators). Rather than proving in advance that the compiler always produces a target code which correctly implements the source code (compiler verification), each individual translation (i.e. a run of the compiler) is followed by a validation phase which verifies that the target code produced on this run correctly implements the submitted source program. In order to be a practical alternative to compiler verification, a key feature of this validation is its full automation. 
 
In this paper we demonstrate the feasibility of translation validation for industrial code generators from DC+ -a widely used intermediate format for synchronous languages- to C. We explain the compilation pattern from DC+ to C and advocate new abstraction techniques for a fragment of first order logic as part of the automation of our approach.
6090717
From Testing Theory to Test Driver Implementation
In this article we describe the theoretical foundations for the VVT-RT test system (Verification, Validation and Test for Reactive Real-Time Systems) which supports automated test generation, test execution and test evaluation for reactive systems. VVT-RT constructs and evaluates tests based on formal CSP specifications [6], making use of their representation as labelled transition systems generated by the CSP model checker FDR [3]. The present article provides a sound formal basis for the development and verification of high-quality test tools: Since, due to the high degree of automation offered by VVT-RT, human interaction becomes superfluous during critical phases of the test process, the trustworthiness of the test tool is an issue of great importance. The VVT-RT system will therefore be formally verified so that it can be certified for testing safety-critical systems. The present article represents the starting point of this verification suite, where the basic strategies for test generation and test evaluation used by the system are formally described and verified. VVT-RT has been designed to support automation of both untimed and real-time tests. The present article describes the underlying theory for the untimed case. Exploiting these results, the concepts and high-level algorithms used for the automation of real-time tests are described in a second report which is currently prepared [14]. At present, VVT-RT is applied for hardware-in-the-loop tests of railway and tramway control computers.
43742881
Erratum ("The small model property: how small can it be?" Volume 178, Number 1 [2002], pages 279-293)