Is facilitation a true species interaction?

Current ecological literature considers facilitation to be a positive interaction alongside symbiosis or mutualism. But unlike these interactions, the fitness of one of the species involved in facilitation remains unaffected which precludes coevolution. Therefore, we believe that facilitation is not a true species interaction and should be kept within the framework of succession.Pablo Munguia, Alfredo F. Ojanguren, Andrew N. Evans, Laura Ryckman, Brad Gemmell, Colt Cook, Geoff Hensge

A Comparison Study of Static Mapping Heuristics for a Class of Meta-tasks on Heterogeneous Computing Systems

Heterogeneous computing (HC) environments are well suited to meet the computational demands of large diverse groups of tasks (i. e., a meta- task). The prob lem of mapping (defi ned as matching and scheduling ) these tasks onto the machines of an HC environment has been shown in general to be NP- complete, requir ing the development of heuristic techniques. Selecting the best heuristic to use in a given environment , how ever, remains a di cult problem because comparisons are often clouded by di erent underlying assumptions in the original studies of each heuristic. Therefore, a collection of eleven heuristics from the literature has been selected implemented and analyzed under one set of common assumptions. The eleven heuristics exam ined are Opportunistic Load Balancing, User- Directed Assignment, Fast Greedy, Min min Max- min, Greedy, Genetic Algorithm, Simulated Annealing , Genetic Sim ulated Annealing, Tabu , and A*. This study provides one even basis for comparison and insights into circum stances where one technique will outperform another . The evaluation procedure is speci ed the heuristics are defined and then selected results are compared