A Realtime Human-Computer Ensemble System: Formal Representation and Experiments for Expressive Performance

A human-computer ensemble system is one of time concerned cooperative systems, which performs secondo of an ensemble played by a computer-controlled piano cooperating with primo played by a human performer. For creating expressive performance, a rehearsal program is adopted to this system. By the rehearsal program, the system learns the tendency of the expression that the human performer thinks and/or plans. To do so, the program records his/her performance of solo and calculates the tendency, which depends on not only the performer but also the composition of music itself. Hence, it is necessary for the expressive performance to analyze the score of the composition and to experiment dependent on it. This system is an example of intelligent realtime programs appropriate for formal verification and analysis. N Sigma-labeled calculus is a formal system for verification for such time-concerned programs. In this paper, a logical specification and experimental results for an expressive ensemble system will be introduced.