Physical Sciences and Mathematics Commons^™

A Framework For Controlling Cooperative Agents, Kuo-Chu Lee, William H. Mansfield, Amit P. Sheth

Kno.e.sis Publications

Presents an overview of the ITX (Interacting Transaction) system, which supports complex interactions among cooperating agents in the presence of user interventions that change application objectives and system failures. The system's components and its unique fixed-point criterion for feedback control of iterative interactions are described. An example of a simplified multimedia teleconferencing application is discussed to illustrate the features of the ITX system.

So Far (Schematically) Yet So Near (Semantically), Amit P. Sheth, Vipul Kashyap

Kno.e.sis Publications

In a multidatabase system, schematic conflicts between two objects are usually of interest only when the objects have some semantic affinity. In this paper we try to reconcile the two perspectives. We first define the concept of semantic proximity and provide a semantic taxonomy. We then enumerate and classify the schematic and data conflicts. We discuss possible semantic similarities between two objects that have various types of schematic and data conflicts. Issues of uncertain information and inconsistent information are also addressed.

On Transactional Workflows, Amit P. Sheth, Marek Rusinkiewicz

Kno.e.sis Publications

The basic transaction model has evolved over time to incorporate more complex transactions structures and to take the advantage of semantics of higher-level operations that cannot be seen at the level of page reads and writes. Well known examples of such extended transaction models include nested and multi-level transactions. A number of relaxed transaction models have been defined in the last several years that permit a controlled relaxation of the transaction isolation and atomicity to better match the requirements of various database applications. Correctness criteria other than global serializability have also been proposed. Several examples of extended/relaxed transaction models are …

Abduction In Annotated Logic Programming, Krishnaprasad Thirunarayan

Kno.e.sis Publications

The author investigates techniques to make the logic programming paradigm more expressive for knowledge representation, while simultaneously retaining the computational advantages of efficiency and simplicity. He extends the annotated language of K. Thirunarayan and K. Kifer (1989) in various directions to obtain an enriched representation language. In particular, rule bodies are permitted to be a conjunction of literals, and the rules to be recursive. A class of annotated logic programs called the stratified programs is identified which can be given a unique supported minimal Herbrand model as their meaning. Abductive reasoning is integrated into this annotated logic framework. The notion …

Using Flexible Transactions To Support Multisystem Telecommunication Applications, Mansoor Ansari, Linda Ness, Marek Rusinkiewicz, Amit P. Sheth

Kno.e.sis Publications

Service order provisioning is an important telecommunication application that automates the process of providing telephone services in response to the customer requests. It is an example of a multi-system application that requires access to multiple, independently developed application systems and their databases. In this paper, we describe the design and implementation of a prototype system1 that supports the execution of the Flexible Transactions and its use to develop the service order provisioning application. We argue that such approach may be used to support the development of multi-system, flow-through processing applications in a systematic and organized manner. Its advantages include fast …

Algorithms For Structural Schema Integration, James Geller, Ashish Mehra, Yehoshua Perl, Erich Neuhold, Amit P. Sheth

Kno.e.sis Publications

Current view and schema integration methodologies are driven by semantic considerations, and allow integration of objects only if that is valid from semantic and structural viewpoints. We had introduced a new integration technique called structural integration. It permits integration of objects that have structural similarities, even if they differ semantically. This technique uses the object-oriented Dual Model which separates the representation of structure and semantics.

In this paper we introduce algorithms for structural integration. We apply these algorithms to integrate two views of a large university database schema which had significant structural similarities but differed semantically.

Executing Multidatabase Transactions, Mansoor Ansari, Marek Rusinkiewicz, Linda Ness, Amit P. Sheth

Kno.e.sis Publications

In a multidatabase environment, the traditional transaction model has been found to be too restrictive. Therefore, several extended transaction models have been proposed in which some of the requirements of transaction, such as isolation or atomicity, are optional. The authors describe one of such extensions, the flexible transaction model and discuss the scheduling of transactions involving multiple autonomous database systems managed by heterogeneous DBMS.

The scheduling algorithm for flexible transactions is implemented using L.0, a logically parallel language which provides a framework for concisely specifying the multidatabase transactions and for scheduling them. The key aspects of a flexible transaction specification, …

Specifying Interdatabase Dependencies In A Multidatabase Environment, Marek Rusinkiewicz, Amit P. Sheth, George Karabatis

Kno.e.sis Publications

The problem of interdatabase dependencies and the effect they have on applications updating interdependent data are addressed. A model that allows specifications of constraints among multiple databases in a declarative fashion is proposed. The separation of the constraints from the application programs facilitates the maintenance of data constraints and allows flexibility in their implementation. It allows investigation of various mechanisms for enforcing the constraints, independently of the application programs. By grouping the constraints together, it is possible to check their completeness and discover possible contradictions among them. The concepts of polytransactions, which use interdatabase dependencies to generate a series of …

On The Relationship Between Parsimonious Covering And Boolean Minimization, Venu Dasigi, Krishnaprasad Thirunarayan

Kno.e.sis Publications

Minimization of Boolean switching functions is a basic problem in the design of logic circuits. The designer first comes up with a switching function expressed in terms of several binary input variables that satisfies the desired functionality, and then attempts to minimize the function as a sum of products or product of sums. It turns out that a sum of products form of a switching function that has no redundancy is a union of prime implicants of the function.

In this paper we would like to explicate some of the relationships of the boolean minimization problem to a formalization of …

On Serializability Of Multidatabase Transactions Through Forced Local Conflict, Dimitrios Georgakopoulos, Marek Rusinkiewicz, Amit P. Sheth

Kno.e.sis Publications

The main difficulty in enforcing global serializability in a multidatabase environment lies in resolving indirect transitive conflicts between multidatabase transactions. Indirect conflicts introduced by local transactions are difficult to resolve because the behavior or even the existence of local transactions is not known to the multidatabase system. To overcome these problems, we propose to incorporate additional data manipulation operations in the subtransactions of each multidatabase transaction. We show that if these operations create direct conflicts between subtransactions at each participating local database system, indirect conflicts can be resolved even if the multidatabase system is not aware of their existence. Based …

The Architecture Of Braid: A System For Bridging Al/Db Systems, Amit P. Sheth, Anthony B. O'Hare

Kno.e.sis Publications

We describe the design of BrAID (a Bridge between Artificial Intelligence and Database Management Systems), an experimental system for the efficient integration of logic based Artificial Intelligence (Al) and database (DB) technologies. Features provided by BrAID include (a) access to conventional DBMSs, (b) support for multiple inferencing strategies, (c) a powerful caching subsystem that manages views and employs subsumption to facilitate the reuse of previously cached data, (d) lazy or eager evaluation of queries submitted by the AI system, and (e) the generation of advice by the AI system to aid in cache management and query execution planning. To discuss …

Management Of Interdependent Data: Specifying Dependency And Consistency Requirements, Amit P. Sheth, Marek Rusinkiewicz

Kno.e.sis Publications

Multiple databases that serve the needs of various application systems are considered. One of the significant problems in managing these databases is to maintain the related data items consistent to the required degree. This problem is frequently referred to as `redundant data management'. Since the term `redundancy' tends to imply that the data is unwanted or superfluous, the authors use the more general term `management of interdependent data'. Some preliminary ideas in this area are discussed. The problem of managing interdependent data is characterized, and some important types of interdatabase dependency are identified.

Attribute Relationships: An Impediment In Automating Schema Integration, Amit P. Sheth, Sunit K. Gala

Kno.e.sis Publications

Success in schema integration depends on understanding the semantics of schema components (e.g., entity sets, relationship sets, attributes), and the ability to capture and reason about these semantics. An important objective of our work on schema integration is to automate the reasoning as much as possible, and when not possible, depend on the human input and guidance. A key results of comparing the semantics associated with schema objects is that of determining attribute relationship. Once attribute relationships are determined, the task of object class(e.g., entity sets and relationship sets) integration becomes simpler and can e automated to a great extent. …

Fault Tolerance In A Very Large Database System: A Strawman Analysis, Amit P. Sheth

Kno.e.sis Publications

A simple model is used to study the effect of fault-tolerance techniques and system design on system availability. A generic multiprocessor architecture is used that can be configured in different ways to study the effect of system architectures. Important parameters studied are different system architectures and hardware fault-tolerance techniques, mean time to failure of basic components, database size and distribution, interconnect capacity, etc. Quantitative analysis compares the relative effect of different parameter values. Results show that the effect of different parameter values on system availability can be very significant. System architecture, use of hardware fault tolerance (particularly mirroring), and data …

A Tool For Integrating Conceptual Schemas And User Views, Amit P. Sheth, James A. Larson, Aloysius Cornelio, Shamkant B. Navathe

Kno.e.sis Publications

An interactive tool has been developed to assist database designers and administrators (DDA) in integrating schemas. It collects the information required for integration from a DDA, performs essential bookkeeping, and integrates schemas according to the semantics provided. The authors present the capabilities of this tool by discussing the integration methodology and the user interface of the tool.

An Analysis Of The Effect Of Network Load And Topology On The Performance Of Concurrency Control Algorithm In Distributed Database Systems, Anoop Singhal, Amit P. Sheth, Ming T. Liu

Kno.e.sis Publications

Earlier studies in the performance analysis of concurrency control algorithms in distributed database systems (DDBS) have assumed that the message transmission time between any two nodes of a network is constant. Hence they disregard the effect of communication subnet related parameters such as network traffic, network topology, the capacity of transmission channels and the size of messages transmitted. In this paper an analytical model is used to estimate the delays in transmission channels for a DDBS in a long haul network. The analysis shows that the constant transmission time assumption cannot be justified in many cases and that response time …