William E. Howden
Prof Emeritus, Computer Science and Engineering
Software testing and analysis, error modeling and prevention, software design, and embedded systems.
Professor Howden has worked in the area of program testing and analysis since 1975. He was one of the founders of this research area. He has worked in most areas of testing research, and was responsible for some of the now standard terminology, such as "infeasible paths" and "test oracle". His research in testing has included results in: symbolic evaluation, theory of testing, algebraic testing, random testing, weak mutation testing, event sequence analysis, error-based testing and analysis, comments analysis, program understanding, trustability analysis, functional testing, and empirical studies of effectiveness. He was made a Fellow of the IEEE for his work in functional testing. Professor Howden's current research is in error-based testing. In this approach, human error models are used to guide the application of software testing and analysis. Perhaps the first application of error-based testing and analysis was described in his paper "Comments Analysis and Programming Errors", (1990) which used a simple error model in which there were two basic types: locality and semantic. In the first type, programmers made false assumptions about one part of a program while working on another, sometimes due to forgetting that something had not been done. In the second, they incorrectly interpreted the meanings of variables that were used to stand for less abstract concrete items. A technique based on this model, called comments analysis, was successfully applied to the avionics on the Navy's AV8-B aircraft. Currently, he is working with more elaborate error models including a software interpretation of a classical error model from cognitive science, as described in his paper "Error models and Software Certification". This model is being used to analyze the testing phase of an industrial control system project.
William Howden joined the UCSD faculty in 1974 He received his Ph.D. in 1973 from UCI. He is the co-author of a best selling tutorial on testing, Software Testing and Validation Techniques (2nd edition, IEEE, 1982) of "Functional Program Testing and Analysis". (McGraw-Hill, 1986), and of numerous papers on testing and software validation.
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