Answer the following about the intersection of mathematics and 20th-century music theory, for 10 points each.
[10e] Microtonal composer Harry Partch developed extended tuning systems using this series, which can be used to explain consonance. This divergent series consists of integer multiples of a fundamental frequency.
ANSWER: harmonic series [or overtone series]
[10h] David Lewin proved that two sets with identical examples of this object, called homometric, can be otherwise entirely unrelated. This mathematical object represents the intervals contained in a set of pitch classes.
ANSWER: interval vector [or interval-class vector or absolute pitch-class interval vector; accept APIC vector]
[10m] Students learning serialist composition create matrices in which transposition, retrograde, and this operation have been applied to tone rows. This operation names chord voicings denoted by figured bass symbols like “6 4.”
ANSWER: inversion [or word forms like inverted]
<DM, Classical Music>