13942242
A Scheme of Parallel Processing for MIMD Systems
This paper presents a recognition procedure for parallel tasks in the user program written in a conventional programming language. To establish our program model, it describes the parallelism of the program in tenns of a process flow graph in which the relationships among processes are of predecessors and successors. And finally it presents a parallel processing scheme which realizes automatically the recognition of parallel tasks and schedules these tasks for parallel execution.
21910023
On Universal and Representative Instances for Inconsistent Databases
17317346
Representative instances and γ-acyclic relational schemes
In this paper, we study under what conditions will a pairwise inconsistent relational database ≪R,r≫ have a universal/representative instance L. If R is γ-acyclic and r satisfies all existence constraints, then it is possible to construct a universal instance L, using unmarked nulls, whose total projections onto R yield exactly the relations in r. We show that L would actually be a representative instance under a set of functional dependencies if R satisfies the additional mild condition: for any functional dependency X → A where A is a single attribute, whenever XA is contained in two relation schemes R and R' of R, it follows that R ∩R' is a relation scheme of R, having X as one of its keys.
45839880
Universal and Representative Instances Using Unmarked Nulls
Representative instances are important since in addition to the universal relation view they permit updates in the individual relations; if these updates are locally valid, then they do not violate global consistency. In this paper, we first give conditions under which we can construct a universal instance I which uses only one type of nulls (unmarked nulls) and whose total projections onto the relation schemes yield exactly the database relations. Then, we give a necessary and sufficient condition under which this I is actually a representative instance. Our conditions are simple and easily maintained.
45139817
Alternative methods for the reconstruction of trees from their traversals
It is well-known that given the inorder traversal of a binary tree's nodes, along with either one of its preorder or postorder traversals, the original binary tree can be reconstructed using a recursive algorithm. In this short note we provide a short, elegent, iterative solution to this classical problem.
8520486
Local Area Networks: Software and Related Issues
In this paper, we present a review of the issues that affect the software requirements for a local area network. We introduce protocols for the local area networks and characterize their software needs. Two approaches to operating systems are outlined and examples of each approach are presented. Various applications which use local area networks and performance issues are also discussed.
30110235
Distributed Policies for Data Management - Making Policies Mobile
This paper presents the challenges facing developers of multi-tier information systems in providing effective consistent data policy enforcement, such as access control in these architectures. It introduces “Mobile Policy”(MoP) as a potential solution and presents a framework for using mobile policy in the business logic tier of multi-tier information systems.
16610756
High assurance discretionary access control for object bases
Discretionary access control, based on checking access requests against users' authorizations, does not provide any way of restricting the usage of information once it has been “legally” accessed. This makes discretionary systems vulnerable to Trojan Horses maliciously leaking information. Therefore the need arises for providing additional controls limiting the indiscriminate flow of information in the system. This paper proposes a message filter complementing discretionary authorization control in object-oriented systems to limit the vulnerability of authorization systems to Trojan Horses. The encapsulation property of the object-oriented data model, which requires that access to objects be possible only through defined methods, makes information flow in such systems have a very concrete and natural embodiment in the form of messages and their replies. As a result, information information flow can be controlled by mediating the transmission of messages exchanged between objects. The message filter intercepts every message exchanged between objects to ensure that information is not leaked to objects accessible by users not allowed for it.
18523825
Secure Locking Protocols for Multilevel Database Management Systems
While there are several secure concurrency control protocols for multilevel database management systems, most of them employ timestamp ordering or multiple versions of data or a hybrid protocol that utilizes both. The only known secure locking protocol that maintains single version data and can guarantee serializability, immediately aborts a higher level transaction whenever any of its locks at the lower levels is broken.
14959461
Securely sharing neuroimagery
Shared scientific data, such as neuroimagery, offers great benefits to science. However, data owners must exercise custodial responsibilities which can conflict with the unhindered sharing of their data. Given simple choices of sharing widely or not at all, the result will frequently be no sharing. We hypothesize that neuroimagery sharing will be enhanced if data owners are provided with well-defined intermediate levels of data visibility. In this paper, we describe a broadly applicable data sharing model, Structured Sharing Communities (SSC), in which data becomes incrementally visible to communities structured as a complete partial-order; the associated properties of Privacy and Fairness regulate access to shared data. Within SSC, a customized policy space is defined capturing the sharing relationships among specific collaborators.
9334464
Implementing Consistency Checking in Correlating Attacks
Static analysis of attack sequences (a.k.a topological vulnerability analysis -TVA) studies sequences of attacks that can eventually lead to exploitable vulnerabilities in a network In models where the attacks are specified in terms of their preconditions and post conditions, the sequences that can be launched are those in which the post condition of the antecedent attack implies the precondition of the precedent attack We show a method of doing so, and show the drawbacks in omitting these checks in the CRIM [5]) model.