An Interactive Trichord Space Based on Measures 18–23 of Clermont Pépin’s Toccate no. 3

Clermont Pépin’s Toccate no. 3 , a work for piano composed in 1961, features extensive repetition and sequencing through the development of smaller atonal intervallic motives. Measures 18–23, in particular, manifest several elements that return repeatedly in the course of the work, and consequently a space defined by the objects and transformations characteristic of this passage can provide a framework for interpreting transformational relations throughout the piece. This paper provides such a space, in an interactive format that allows the reader to explore grouping structure within the passage. The space is then expanded to accommodate later passages involving similar motivic material.