Ernst A. Heinz

Experimental evaluation in computer science: a quantitative study

A survey of 400 recent research articles suggests that computer scientists publish relatively few papers with experimentally validated results. The survey includes complete volumes of several refereed computer science journals, a conference, and 50 titles drawn at random from all articles published by ACM in 1993. The journals of Optical Engineering (OE) and Neural Computation (NC) were used for comparison. Of the papers in the random sample that would require experimental validation, 40% have none at all. In journals related to software engineering, this fraction is 50%. In comparison, the fraction of papers lacking quantitative evaluation in OE and NC is only 15% and 12%, respectively. Conversely, the fraction of papers that devote one fifth or more of their space to experimental validation is almost 70% for OE and NC, while it is a mere 30% for the computer science (CS) random sample and 20% for software engineering. The low ratio of validated results appears to be a serious weakness in computer science research. This weakness should be rectified for the long-term health of the field. The fundamental principle of science, the definition almost, is this: the sole test of the validity of any idea is experiment. —Richard P. Feynman. Beware of bugs in the above code; I have only proved it correct, not tried it. —Donald E. Knuth

Using Wearable Sensors for Real-Time Recognition Tasks in Games of Martial Arts - An Initial Experiment

Beside their stunning graphics, modern entertainment systems feature ever-higher levels of immersive user-interaction. Today, this is mostly achieved by virtual (VR) and augmented reality (AK) setups. On top of these, we envision to add ambient intelligence and context awareness to gaming applications in general and games of martial arts in particular. To this end, we conducted an initial experiment with inexpensive body-worn gyroscopes and acceleration sensors for the chum kiu motion sequence in wing tsun (a popular form of kung fu). The resulting data confirm the feasibility of our vision. Fine-tuned adaptations of various thresholding and pattern-matching techniques known from the fields of computational intelligence and signal processing should suffice to automate the analysis and recognition of important wing tsun movements in real time. Moreover, the data also seem to allow for the possibility of automatically distinguishing between certain levels of expertise and quality in executing the movements.

Automatic synchronisation elimination in synchronous FORALLs

This paper investigates a promising optimization technique that automatically eliminates redundant synchronization barriers in synchronous FORALLs. We present complete algorithms for the necessary program restrictions and subsequent code generation. Furthermore, we discuss the correctness, complexity, and performance of our restructuring algorithm before we finally evaluate its practical usefulness by quantitative experimentation. The experimental evaluation results are very encouraging. An implementation of the optimization algorithms in our Modula-2* compiler eliminated more than 50% of the originally present synchronization barriers in a set of seven parallel benchmarks. This barrier reduction improved the execution times of the generated programs by over 40% on a MasPar MP-1 with 16384 processors and by over 100% on a sequential workstation.<<ETX>>

Compiling machine-independent parallel programs

Initial evidence is presented that explicitly parallel, machine-independent programs can automatically be translated into parallel machine code that is competitive in performance with hand-written code.The programming language used is Modula-2*, an extension of Modula-2, which incorporates both data and control parallelism in a portable fashion. An optimizing compiler targeting MIMD, SIMD, and SISD machines translates Modula-2* into machine-dependent C code.The performance of the resulting code is compared to that of equivalent, carefully hand-coded and tuned prograins. On a MasPar MP-1 (SIMD machine with up to 16k processors) the Modula-2* programs typically achieve 80% of the performance of the hand-coded parallel versions. When targeting sequential processors, the Modula-2* programs reach 90% of the performance of hand-coded sequential C. (There are no MIMD results yet.)The effects of two major optimization techniques, synchronization point elimination and data/process alignment are also quantified.

The Modula-2* environment for parallel programming

Presents a portable parallel programming environment for Modula-2*, an explicitly parallel machine-independent extension of Modula-2. Modula-2* offers synchronous and asynchronous parallelism, a global single address space, and automatic data and process distribution. The Modula-2* system consists of a compiler, a debugger, a cross-architecture make, graphical X Windows control panel, run-time systems for different machines, and sets of scalable parallel libraries. The existing implementation targets the MasPar MP series of massively parallel processors (SIMD), the KSR-1 parallel computer (MIMD), heterogeneous LANs of workstations (MIMD), and single workstations (SISD). We describe the important components of the Modula-2* environment, and discuss selected implementation issues. We focus on how we achieve a high degree of portability for our system, while at the same time ensuring efficiency.<<ETX>>

Project Triton: towards improved programmability of parallel computers

The main objective of Project Triton is adequate programmability of massively parallel computers. This goal can be achieved by tightly coupling the design of programming languages and parallel hardware.