IEEE Transactions on Knowledge and Data Engineering

Describes a new, logic-based methodology for analyzing observations. The key features of this "logical analysis of data" (LAD) methodology are the discovery of minimal sets of features that are necessary for explaining all observations and the detection of hidden patterns in the data that are capable of distinguishing observations describing "positive" outcome events from "negative" outcome events... View full abstract»

Proposes a hierarchical error detection framework for a software-implemented fault tolerance (SIFT) layer of a distributed system. A four-level error detection hierarchy is proposed in the context of Chameleon, a software environment for providing adaptive fault tolerance in an environment of commercial off-the-shelf (COTS) system components and software. The design and implementation of a softwar... View full abstract»

Coordination among processes in a distributed system can be rendered very complex in a large-scale system where messages may be delayed or lost and when processes may participate only transiently or behave arbitrarily, e.g. after suffering a security breach. In this paper, we propose a scalable architecture to support coordination in such extreme conditions. Our architecture consists of a collecti... View full abstract»

An integrated checkpointing and recovery scheme which exploits the low latency and high coverage characteristics of a concurrent error detection scheme is presented. Message dependency, which is the main source of multistep rollback in distributed systems, is minimized by using a new message validation technique derived from the notion of concurrent error detection. The concept of a new global sta... View full abstract»

Past research in message logging has focused on studying the relative overhead imposed by pessimistic, optimistic and causal protocols during failure-free executions. In this paper, we give the first experimental evaluation of the performance of these protocols during recovery. Our results suggest that applications face a complex tradeoff when choosing a message logging protocol for fault toleranc... View full abstract»

Functional dependencies (FDs) and inclusion dependencies (INDs) are the most fundamental integrity constraints that arise in practice in relational databases. In this paper, we address the issue of normalization in the presence of FDs and INDs and, in particular, the semantic justification for an inclusion dependency normal form (IDNF), which combines the Boyce-Codd normal form with the restrictio... View full abstract»

The TMO (Time-triggered Message-triggered Object) scheme was formulated as a major extension of the conventional object structuring schemes with the idealistic goal of facilitating general-form design and timeliness-guaranteed design of complex real-time application systems. Recently, as a new scheme for realizing TMO-structured distributed and parallel computer systems that are capable of both ha... View full abstract»

Powerful solutions enabling interoperability must allow applications to evolve and the requirements of shared databases to change, while minimizing such changes on other integrated applications. Several approaches have been proposed to make interoperability possible by using object-oriented techniques. These approaches may generate a large number of schema versions over time, resulting in an exces... View full abstract»

This paper proposes new definitions of lower and upper approximations, which are basic concepts of the rough set theory. These definitions follow naturally from the concept of ambiguity introduced in this paper. The new definitions are compared to the classical definitions and are shown to be more general, in the sense that they are the only ones which can be used for any type of indiscernibility ... View full abstract»

Proposes a new measure of fuzzy equality (FE) comparison based on the similarity of possibility distributions. We define a type of fuzzy equi-join based on the new FE comparison and allow threshold values to be associated with predicates of the join condition. A sort-merge join algorithm based on a partial order of intervals is used to evaluate the fuzzy equi-join. In order for the evaluation to b... View full abstract»

It is striking that the optimization of disjunctive queries-i.e. those which contain at least one OR-connective in the query predicate-has been vastly neglected in the literature, as well as in commercial systems. In this paper, we propose a novel technique, called bypass processing, for evaluating such disjunctive queries. The bypass processing technique is based on new selection and join operato... View full abstract»

Graphs are a powerful and universal data structure useful in various subfields of science and engineering. In this paper, we propose a new algorithm for subgraph isomorphism detection from a set of a priori known model graphs to an input graph that is given online. The new approach is based on a compact representation of the model graphs that is computed offline. Subgraphs that appear more than on... View full abstract»

The problem of optimally placing data on disks (ODP) to maximize disk-access performance has long been recognized as important. Solutions to this problem have been reported for some widely available disk technologies, such as magnetic CAV and optical CLV disks. However, important new technologies such as multizoned magnetic disks, have been recently introduced. For such technologies no formal solu... View full abstract»