Algorithms and Data Structure

The dominant parallel programming models for shared memory computers, Pthreads and OpenMP, are both thread-centric in that they are based on explicit management of tasks and enforce data dependencies and output ordering through task management. By com- parison, the Cray XMT programming model is data-centric where the primary concern of the programmer is managing data dependencies, allowing threads to progress

In this paper we present a new attack technique that allows extraction of selected database content relying merely on the attacker's ability to perform database transactions (INSERTs or UPDATEs) that are usually available to any anonymous database user. Our attack technique uses a side-channel timing attack in the realm of database indexing algorithms and data structures. We prove that by exploiting the inherent characteristics of the most commonly used indexing data structures and algorithms in today's commercial database management systems it is possible to extract privacy-sensitive data from a database. In particular we prove, both in theory and practice that it is feasible to do so if the B-tree data structure is used and the attacker is able to insert records with chosen data that is used as the search key of one of the table's indexes. We present experimental results of a successful attack implementation against MySQL and provide conclusions and ideas for further r...

This paper describes a project for use in computer networks courses, implementation of the Reliable Transport Protocol (RTP), that gives students hands-on experience with network protocol concepts and construction. Lecture topics such as the protocol layering model, sliding window protocols, packet formats and headers, techniques for establishing and closing connections, and UDP sockets programming are all driven home via first-hand

Many modern programming languages support basic generics, sufficient to implement type-safe polymorphic containers. Some languages have moved beyond this basic support, and in doing so have enabled a broader, more powerful form of generic programming. This paper reports on a comprehensive comparison of facilities for generic programming in eight programming languages: C++, Standard ML, Objective Caml, Haskell, Eiffel, Java, C# (with its proposed generics extension), and Cecil. By implementing a substantial example in each of these languages, we illustrate how the basic roles of generic programming can be represented in each language. We also identify eight language properties that support this broader view of generic programming: support for multi-type concepts, multiple constraints on type parameters, convenient associated type access, constraints on associated types, retroactive modeling, type aliases, separate compilation of algorithms and data structures, and implicit argument t...

We present an elegant and simple to implement framework for performing out-of-core visualization and view-dependent refinement of large terrain surfaces. Contrary to the recent trend of increasingly elaborate algorithms for large-scale terrain visualization, our algorithms and data structures have been designed with the primary goal of simplicity and efficiency of implementation. Our approach to managing large terrain data also departs from more conventional strategies based on data tiling. Rather than emphasizing how to segment and efficiently bring data in and out of memory, we focus on the manner in which the data is laid out to achieve good memory coherency for data accesses made in a top-down (coarse-to-fine) refinement of the terrain. We present and compare the results of using several different data indexing schemes, and propose a simple to compute index that yields substantial improvements in locality and speed over more commonly used data layouts.

Our second contribution is a new and simple, yet easy to generalize method for view-dependent refinement. Similar to several published methods in this area, we use longest edge bisection in a top-down traversal of the mesh hierarchy to produce a continuous surface with subdivision connectivity. In tandem with the refinement, we perform view frustum culling and triangle stripping. These three components are done together in a single pass over the mesh. We show how this framework supports virtually any error metric, while still being highly memory and compute efficient.

1. Introduction. The nite element method for computing approximate solu-tions to linear elliptic partial di erential equations in the plane 12] is usually consid-ered to have three parts: subspace selection, matrix assembly, and matrix solution. If a particular approximate solution is ...

This paper presents a taxonomy for algorithm simulation exercises that allow to build learning environments that not only portray a variety of algorithms and data structures, but also distribute tracing exercises to the student and then automatically evaluates his/her answer to the exercises. The taxonomy systematically classies the exercises into 8 separate categories that have 8 subcategories each. Each category

All programmers should understand the concept of software families and know the techniques for constructing them. This paper suggests that classic problems, such as well-known algorithms and data structures, are good sources for examples to use in a study of software family design. The paper describes two case studies that can be used to introduce students in a Java software design course to the construction of software families using software frameworks. The first is the family of programs that use the well-known divide and conquer algorithmic strategy. The second is the family of programs that carry out traversals of binary trees.