Lyman L. Johnson

Breeding software test cases with genetic algorithms

Faulty software is usually costly and possibly life threatening as software becomes an increasingly critical component in a wide variety of systems. Thorough software testing by both developers and dedicated quality assurance staff is one way to uncover flaws. Automated test generation techniques can be used to augment the process, free of the cognitive biases that have been found in human testers. This paper focuses on breeding software test cases using genetic algorithms as part of a software testing cycle. An evolving fitness function that relies on a fossil record of organisms results in interesting search behaviours, based on the concepts of novelty, proximity, and severity. A case study that uses a simple, but widely studied program is used to illustrate the approach. Several visualization techniques are also introduced to analyze particular fossil records, as well as the overall search process.

Breeding software test cases for complex systems

The potential cost savings from handling software errors within a development cycle, rather than subsequent cycles, has been estimated at 38.3 billion dollars. Such figures emphasize that current testing methods are inadequate, and that helping reduce software bugs and errors is an important area of research with a substantial payoff. This paper reports on research using genetic algorithms for test case generation for systems level testing, building on past work at the unit testing level. The goals of the paper are to explore the use of genetic algorithms for testing complex distributed systems, as well as to develop a framework or vocabulary of important environmental attributes that characterize complex systems failures. In addition, preliminary visualization techniques that might help software developers to understand and uncover complex systems failures are explored.

Población y espacio en el Buenos Aires del siglo XVIII

Durante el siglo XVIII Buenos Aires se convirtio en una ciudad importante del imperio espafiol en America. Comenzando en las primeras decadas y prolongandose ininterrumpidamente durante todo el siglo, el comercio (tanto legal como el contrabando) y la creciente actividad militar en el Rio de la Plata dio a la ciudad una nueva importancia economica y estrategica. Poco a poco, Buenos Aires paso a ser un floreciente centro comercial y burocratico.

Cities and Wealth in the South Atlantic: Buenos Aires and Rio de Janeiro before 1860

Rio de Janeiro and Buenos Aires, the leading cities of the South Atlantic, experienced substantial growth in wealth holding during the first half of the nineteenth century. In this article, we argue that this growth is best interpreted in a broad, comparative framework, which examines these cities in relation to their internal demographic and institutional arrangements and to their external links to the Atlantic World. Our research emphasizes three major comparative findings. First, according to our samples, both Rio de Janeiro and Buenos Aires experienced substantial growth in wealth holding from the 1820s through the 1850s, well before their participation in the better-known global economic expansion of the late nineteenth century. Second, residents of both South Atlantic cities held wealth broadly similar in scale with their counterparts in comparable cities in North America. And third, wealth inequality was probably no greater in Rio de Janeiro and Buenos Aires than in contemporary cities in the United States. Moreover, we believe that these increases in average wealth holding, as well as changes in the allocation of wealth across sectors, suggests economies that were growing rapidly while becoming more complex. In order to arrive at these findings we synthesized a growing new literature on the economic dynamism of the early nineteenth century in southeastern

USING GENETIC ALGORITHMS AND DECISION TREE INDUCTION TO CLASSIFY SOFTWARE FAILURES

This paper describes two laboratory experiments designed to evaluate a failure-pursuit strategy for system level testing. In the first experiment, two GAs are used to automatically generate test suites that are rich in failure-causing test cases. Their performance is compared to random generation. The resulting test suites are then used to train a series of decision trees, producing rules for classifying other test cases. Finally, the performance of the classification rules is evaluated empirically. The results indicate that the combination of GA-based test case generation and decision tree induction can produce rules with high-predictive accuracy that can assist human testers in diagnosing the cause of system failures.

Urbanization in Colonial Latin America

The nations of modern Latin America are dominated politically and economically by large, rapidly expanding cities. In many countries-Argentina, Uruguay, and Peru, for example-nearly a third of the total national population lives in the capital city. Despite the obvious importance of the region’s cities today and the subsequent development of a large, if uneven, body of scholarship dealing with the problems of contemporary urbanization, relatively few scholars have studied the colonial antecedents of Latin America’s urban development. In general, however, the existing scholarship, although limited in geographical and temporal coverage, does provide a strong foundation for future work. In this article we will provide a brief overview of the development of the colonial system of cities. After reviewing the model for sixteenth-century urbanization, the chronology of

Aftershocks: Earthquakes and Popular Politics in Latin America.

Earthquakes have helped shape the history of many Latin American nations. The effects of floods, droughts, hurricanes, and earthquakes and tsunamis have destroyed peoples lives and their built environments, and changed land forms, such as mountains, rivers, forests, and canyons. This collection of essays focuses on earthquakes in Latin America since the mid-nineteenth century. Often interpreted as evidence of Gods wrath, internalized as punishment for sins, and serving as detonators of revolutions, earthquakes have shined an unforgiving light on political corruption and provided new opportunities to previously disadvantaged groups. These analyses of earthquakes reveal the human role in shaping interactions with our environment.

CLAH Lecture: Have We Loved the Book to Death?

Let me begin by thanking you for this honor. Like most of you I belong to many professional organizations and all of them have provided me with the opportunity to grow intellectually as well as forge the enduring professional associations that have so enriched my life. From the beginning of my career, however, CLAH has always served as my professional home. It is because I consider myself fortunate to be one of you that this award means so much to me. I am grateful indeed.