Repetition-Structure Inference with Formal Prototypes

The concept of form in music encompasses a wide range of musical aspects, such as phrases and (hierarchical) segmentation, formal functions, cadences and voice-leading schemata, form templates, and repetition structure. In an effort towards a unified model of form, this paper proposes an integration of repetition structure (i.e., which segments of a piece occur several times) and formal templates (such as AABA). While repetition structure can be modeled using context-free grammars, most prior approaches allow for arbitrary grammar rules. Constraining the structure of the inferred rules to conform to a small set of templates (meta-rules) not only reduces the space of possible rules that need to be considered but also ensures that the resulting repetition grammar remains interpretable in the context of musical form. The resulting formalism can be extended to cases of varied repetition and thus constitutes a building block for a larger model of form.