Membrane Algorithms

A new type of approximate algorithms for optimization problems, called membrane algorithms, is proposed, which can be seen as an application of membrane computing to evolutionary computing. A membrane algorithm consists of several membrane separated regions, where subalgorithms and tentative solutions to the optimization problem to be solved are placed, as well as a solution transporting mechanism between adjacent regions. The subalgorithms improve tentative solutions simultaneously. After that, the best and worst solutions in a region are sent to adjacent inner and outer regions, respectively. By repeating this process, a good solution will appear in the innermost region. The algorithm terminates if a terminate condition is satisfied. A simple condition of this type is the number of iterations, while a little more sophisticated condition becomes true if the good solution is not changed during a predetermined period. Computer experiments show that such algorithms are rather efficient in solving the travelling salesman problem.