Adaptive neighbourhood search for the component deployment problem

Since the establishment of the area of search-based software engineering, a wide range of optimisation techniques have been applied to automate various stages of software design and development. Architecture optimisation is one of the aspects that has been automated with methods like genetic algorithms, local search, and ant colony optimisation. A key challenge with all of these approaches is to adequately set the balance between exploration of the search space and exploitation of best candidate solutions. Different settings are required for different problem instances, and even different stages of the optimisation process. To address this issue, we investigate combinations of different search operators, which focus the search on either exploration or exploitation for an efficient variable neighbourhood search method. Three variants of the variable neighbourhood search method are investigated: the first variant has a deterministic schedule, the second variant uses fixed probabilities to select a search operator, and the third method adapts the search strategy based on feedback from the optimisation process. The adaptive strategy selects an operator based on its performance in the previous iterations. Intuitively, depending on the features of the fitness landscape, at different stages of the optimisation process different search strategies would be more suitable. Hence, the feedback from the optimisation process provides useful guidance in the choice of the best search operator, as evidenced by the experimental evaluation designed with problems of different sizes and levels of difficulty to evaluate the efficiency of varying the search strategy.