The domain of computer music is an interesting area which combines computer science and music art. We propose a music accompaniment system using a variable-length genetic algorithm. Via the system one can make the music corresponded to his demands. In the style music accompaniment we analyze some important characteristic of pop music, and propose a new chromosome representation scheme to include the concept of rhyme, chord and melody. Chord progression is used as one of the evaluation criterions in this thesis. The system allows a user to input melody, to select emotion and rhyme, and the system will automatically generate the appropriate accompaniment based on the database compiled from some music theory relating to the chord progression. In addition, the system allows a user to select his favorite accompaniment that generated by the system. Based on the user selected accompaniment the system will generate similar accompaniments for the user.

Wireless network placement of transmitters, such as base stations for 2G and 3G, access points for WLAN, is a NP-hard problem, since many factors have to be considered, like QoS, coverage, cost, etc. In wireless network placement problem, the goal is to find a set of transmitters which achieves the widest coverage on a given map and spends the minimal cost. In this thesis, we propose a novel variable-length genetic algorithm for solving this problem. Most of existing methods for solving wireless network placement problem, to our best knowledge, users must assign an upper bound or a total number of transmitters for placement. Unlike these existing methods, the proposed algorithm can search the optimal number of transmitters automatically. In addition, the proposed algorithm can find near optimal solutions even in heterogeneous transmitters placement problem, i.e., transmitters with different power radius or cost. The results on several benchmarks are very close to the optimal solutions, which validate the capability of the proposed method in finding the numbers, the types, are the positions of transmitters in heterogeneous wireless network environment.