MIDIME is a software architecture that houses improvisational agents that react to MIDI messages from a finger-picked guitar. They operate in a pipeline whose first stage converts MIDI messages to a map of the state of instrument strings over time, and whose second stage selects rhythmic, modal, chordal, and melodic interpretations from the superposition of interpretations latent in the first stage. These interpretations are nondeterministic, not because of any arbitrary injection of randomness by an algorithm, but because guitar playing is nondeterministic. Variations in timing, tuning, picking intensity, string damping, and accidental or intensional grace notes can affect the selections of this second stage. The selections open to the second stage, as well as the third stage that matches second stage selections to a stored library of composition fragments, reflect the superposition of possible perceptions and interpretations of a piece of music. This paper concentrates on these working analytical stages of MIDIME. It also outlines plans for using the genetic algorithm to develop improvisational agents in the final pipeline stage.

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