Abstract Introduced in 1993, the DIRECT global optimization algorithm provided a fresh approach to minimizing a black-box function subject to lower and upper bounds on the variables. In contrast to the plethora of nature-inspired heuristics, DIRECT was deterministic and had only one hyperparameter (the desired accuracy). Moreover, the algorithm was simple, easy to implement, and usually performed well on low-dimensional problems (up to six variables). Most importantly, DIRECT balanced local and global search (exploitation vs. exploration) in a unique way: in each iteration, several points were sampled, some for global and some for local search. This approach eliminated the need for “tuning parameters” that set the balance between local and global search. However, the very same features that made DIRECT simple and conceptually attractive also created weaknesses. For example, it was commonly observed that, while DIRECT is often fast to find the basin of the global optimum, it can be slow to fine-tune the solution to high accuracy. In this paper, we identify several such weaknesses and survey the work of various researchers to extend DIRECT so that it performs better. All of the extensions show substantial improvement over DIRECT on various test functions. An outstanding challenge is to improve performance robustly across problems of different degrees of difficulty, ranging from simple (unimodal, few variables) to very hard (multimodal, sharply peaked, many variables). Opportunities for further improvement may lie in combining the best features of the different extensions.

Researchers have established that information technology (IT) can improve firms’ productivity. Whether improved productivity leads to additional investment in IT, however, remains largely uninvestigated. In this paper, we consider whether the relationship between productivity and subsequent IT investment might be positive, negative, or ad hoc, and hypothesize that this relationship is positive. We analyze seven years of panel data from 1236 healthcare firms and present empirical evidence supporting our hypothesis. When our finding is combined with extant research, it becomes reasonable to propose that unidirectional causality does not fully describe the process of IT business value creation. Instead, we argue that existing static models of IT business value with unidirectional causality can be recast as dynamic models that explicitly incorporate multiple time periods and a positive feedback relationship to more accurately capture the complexity of this process. The creation of IT business value can thus be understood as a positive feedback model where IT investment in a given time period builds the stock of IT inputs, where those IT inputs then impact productivity, and where productivity leads to IT investment in a future time period, beginning the cycle anew.

A parallel rendering environment is being developed to utilize the IBM Scaleable Graphics Engine (SGE), a hardware frame buffer for parallel computers. Goals of this software development effort include finding efficient ways of producing and displaying graphics generated on IBM SP nodes and of assisting programmers in adapting or creating scientific simulation applications to use the SGE. Four software development phases discussed utilize the SGE: tunneling, SMP rendering, development of an OpenGL API implementation which utilizes the SGE in parallel environments, and additions to the SGE-enabled OpenGL implementation that uses threads. The performance observed in software tests show that programmers would be able to utilize the SGE to output interactive graphics in a parallel environment.