David M. Arnow

Green’s function Monte Carlo for few fermion problems

The Green’s function Monte Carlo method used for obtaining exact solutions to the Schrodinger equation of boson systems is generalized to treat systems of several fermions. We show that when it is possible to select eigenfunctions of the Hamiltonian based on physical symmetries, the GFMC method can be used to yield the lowest energy state of that symmetry. In particular, the lowest totally antisymmetric eigenfunction, the fermion ground state, can be obtained. Calculations on several two‐ and three‐body model problems show the method to be computationally feasible for few‐body systems.

WebToTeach: an interactive focused programming exercise system

In this paper, we describe a web-based interactive programming exercise system, aimed in part at addressing the retention crisis in computer science education. The system is based on automatic program-checking software. It is designed to be easy for students and faculty to use, to support a wide variety of programming exercises, and to encourage sharing of exercises among faculty. The system is immediately available to anyone with web access with no arrangements needed. Special features such as roster maintenance can be arranged with a minimum of effort.

On-line programming examinations using Web to teach

Using the automated code-checking capability of the WebToTeach system, we have built WebToTest, a system for administering on-line programming examination.The system successfully addresses many of the issues raised by recent work in on-line exams by providing reliable automatic checking of exam questions and a secure, restricted programming environment useable by the students during the exam. Its web-based character makes it amenable to distance education applications. Furthermore, because examinations may be administered on any collection of computers that provide a browser, and thus do not require reservation of the student programming labs.

:-)When you grade that: using e-mail and the network in programming courses

We have been using network facilities and e-mail for submitting and responding to homework assignments, faculty student communication and as a general means for providing instructional maten’al (assignments, solutions, sample quizzes, etc.). The most important component of this is a homework programming assignment checker. These methods have been successful in alleviating a number of problems, including student dificulty in making faculty oftice hours, slow feedback on homework assignments, heavier teaching loads and larger classes. In addition, several unexpected benefits resulted as well.

Teaching programming to liberal arts students: using loop invariants

Loop invariants have long been present in advanced undergraduate and graduate courses on programming methodology or program correctness. Recently there has been an increased interest in using loop invariants in teaching more elementary courses. In this paper, its successful use in teaching elementary programming in a computer literacy course for non-majors is described. The techniques described here, that are necessary in order to work successfully with this population, are also applicable to the teaching of programming to computer science majors.

An empirical comparison of B-trees, compact B-trees and multiway trees

It is well-known that the B-tree data structure yields excellent worst-case search costs and for that reason is widely employed in the organization of external files and in the implementation of data bases. In this paper, we examine general B-trees empirically and compare them with a less restrictive structure, the general multiway tree, and a more restrictive structure, the compact B-tree. We compare search costs, insertion costs, and space costs of these three structures for both small and large orders and indicate their relative utility for large and small data sets. Although there are cases when general multiway trees are more effective than B-trees, this is not the case for most practical situations. Compact B-trees are also shown to degrade rapidly in the presence of insertions and are therefore only useful for static data sets.

XDP: a simple library for teaching a distributed programming module

XDP is a simplified interface to the DP distributed programming library. I describe its use in a course on workstation programming, a pragmatic course whose mission is to cover concurrent programming, graphical user interfaces and event driven programming as well as network and distributed computing. Using XDP, rather than the native socket interface, makes it feasible to cover the last topics, squeezed though they are into a rather overloaded course. Finding (or building) teaching tools like XDP will become increasingly essential as more demands are placed on undergraduate CS curriculum coverage.

Parallel integer goal programming

We present a vertical integration of linear programming, logic programming and distributed programming which in this paper is applied to a family of administrative problems that occur in many businesses and other organizations. These problems, which require integer goal programming, are both difficult to model and computationally demanding. 2LP is both a modeling language and a language that provides control for solving disjunctive programming problems. In 2LP integer goal programs can be modeled in an elegant manner. Most important to this work, 2LP supports a mechanism for bringing parallel computing to bear on these problems. Using the distributed programming library DP as a substratum, we have developed a scheme for parallelizing integer goal programs in an eficient way. The result is twofold: a family of applications of broad interest and a systematic way of parallelizing them on a distributed programming system.

Concurrency the first year (panel session): experience reports

Concurrency as a topic for CS 1 and 2 is at that point in its evolution where early adopters have already obtained several years of experience, but the bulk of educators are still considering their options. Thus we are at the perfect moment for a panel where the early adopters report on their experiences to the broader community of educators considering introducing concurrency in the first year. Each of the panelists has at least three iterations of experience with concurrency in the first year, and will report both on the course design decisions they made and on how those designs have played out. We will then leave thirty minutes for discussion.

The Iliad and the WHILE loop: computer literacy in a liberal arts program

A required computer literacy course whose design and implementation were greatly influenced by that of required courses in classics and other liberal arts is described. The course is an instance of the new trend of principles-based courses, but does not take the survey approach. Topics are chosen selectively on the basis of importance to the field, usefulness in demystifying the computer itself, and their ability to be compatible with a hands-on, exercise-oriented pedagogy. Topics include propositional logic, digital circuit design, information representation, a Pascal subset, program hierarchies and software engineering principles. The course has been successfully run in over 30 sections with over 1000 students.