"David B. Lewin made his greatest impact, however, as an analyst of music. His innovative approach to the structure of music considered not only the "things" within a composition, but also the relationships among those things. In his transformational analysis, musical space took shape in intervals of "distance" (e.g., pitch) and also of "time" (e.g., rhythm). Such study of mathematical coherence in music [based upon the higher mathematics of group theory, algebraic topology, and projective geometry] proved inclusive, breaking down conventional boundaries between genres, periods, and styles. A consummate and dedicated teacher, Lewin influenced generations of students."
And what's wrong with conventional -- or, indeed, unconventional -- boundaries between genres, periods, and styles.
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