16011778
A Uniform System for Publishing and Maintaining XML Data
XML has become the prime standard for data exchange on the Web. To exchange data residing in Databases, one needs to publish it in XML. Data publishing is often done with a predefined “schema.” The chapter proposes a new approach for schema-directed publishing of relational data in XML, based on the novel notion of attribute transformation grammars (ATGs). ATGs provide guidance on how to define views conforming to target schemas (DTDs), and automatically ensure schema conformance. The chapter also develops an incremental algorithm for maintaining XML views produced by ATGs, based on new incremental computation techniques that capitalize on the hierarchical structure of XML data and unique features of the ATGs. Taking real-life data from Gene Ontology (GO), this chapter also demonstrates how this system can efficiently publish the GO data in XML with respect to a predefined recursive DTD, and how it incrementally updates the target XML data in response to changes to the underlying GO database.
17179157
Conditional Functional Dependencies for Data Cleaning
We propose a class of constraints, referred to as conditional functional dependencies (CFDs), and study their applications in data cleaning. In contrast to traditional functional dependencies (FDs) that were developed mainly for schema design, CFDs aim at capturing the consistency of data by incorporating bindings of semantic ally related values. For CFDs we provide an inference system analogous to Armstrong's axioms for FDs, as well as consistency analysis. Since CFDs allow data bindings, a large number of individual constraints may hold on a table, complicating detection of constraint violations. We develop techniques for detecting CFD violations in SQL as well as novel techniques for checking multiple constraints in a single query. We experimentally evaluate the performance of our CFD-based methods for inconsistency detection. This not only yields a constraint theory for CFDs but is also a step toward a practical constraint-based method for improving data quality.
4599441
A Hypothesis-Based Approach to Detecting Runtime Violations
We have developed an approach to apply formal methods to represent program source code as a model and use an automated theorem prover to detect runtime violations by doing static analysis. Unlike other proof-based program verification approaches, this approach is based on a hypothesis to develop the implicit specification information, such as invariants, preconditions, postconditions, then using an automated theorem prover to verify the correctness of each statement in the program. Our research work can catch those runtime exceptions that are beyond the capability of control flow-based analysis in compilers.
1493304
On random points in the unit disk
Let n be a positive integer and λ > 0 a real number. Let Vn be a set of n points in the unit disk selected uniformly and independently at random. Define G(λ, n) to be the graph with vertex set Vn, in which two vertices are adjacent if and only if their Euclidean distance is at most λ. We call this graph a unit disk random graph. Let λ = c √ lnn/n and let X be the number of isolated points in G(λ, n). We prove that almost always X ∼ n1−c2 when 0 ≤ c < 1. It is known that if λ = √ (ln n + φ(n))/n where φ(n) → ∞, then G(λ, n) is connected. By extending a method of Penrose, we show that under the same condition on λ, there exists a constant K such that the diameter of G(λ, n) is bounded above by K · 2/λ. Furthermore, with a new geometric construction, we show that when λ = c √ lnn/n and c > 2.26164 · · · , the diameter of G(λ, n) is bounded by (4 + o(1))/λ; and we modify this construction to yield a function c(δ) > 0 such that the diameter is at most 2(1 + δ + o(1))/λ when c > c(δ). ∗This is a preprint of an article accepted for publication in Random Structures and Algorithms c ©2005. †Partially supported by NSF grant DMS-9977354. ‡Partially supported by NSF grant DMS-0245526, DMS-0308827 and a Sloan Fellowship. The author is also affiliated with Dalian University of Technology.
22388831
PROOF: A Parallel Object-Oriented Functional Computation Model
Abstract Despite the rapid development of parallel computer architectures in recent years, software development technology for parallel processing systems is still largely inadequate. An integrated object-oriented and functional computation model, called PROOF, is developed to facilitate the effective development of software for parallel processing systems. It will fully explore the parallelism in software systems and reduce the development effort by supporting software engineering principles, such as information hiding, modularity, modifiability, and reusability. In PROOF, we achieve the coherent integration of (1) parallelism and inheritance of objects and (2) referential transparency and history sensitivity of functions. The major features and the semantics of PROOF are presented. A parallel programming language and a software development approach based on PROOF are under development. Implementation issues are also discussed.
28697957
The maximum size of graphs satisfying a degree condition
Let G be a simple graph of order n without isolated vertices. If the integer h satisfies 
h ⩾ maxυ ϵ V(G)minu ψ N(V)(degGu) 
then G is called an Fn(h)-graph. In this note the maximum size of Fn(h)-graphs is determined. A result of Krol and Veldman on critically h-connected graphs follows as a corollary.
2524138
Code synthesis based on object-oriented design models and formal specifications
Presents an approach to synthesizing functional and robust code from object-oriented design models and Z data and operation specifications. The approach used is based on an integrated notation of the Unified Modeling Language (UML) and a slightly extended Z notation to include object-oriented concepts and structures. Our approach generates fully functional code which can be compiled and executed without modifications. The information from object-oriented analysis and design models along with the formal specifications are combined, analyzed and translated into an intermediate representation from which code can be generated. A research prototype has been developed to demonstrate the feasibility and the effectiveness of our approach.