Neutral and interordinal intervals in MOS scales: Difference between revisions
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Given a tuning of a primitive (single-period) [[mos]] pattern aLbs with a > b, we may define two types of notes "in the cracks of" interval categories defined by aLbs: | Given a tuning of a primitive (single-period) [[mos]] pattern aLbs with a > b, we may define two types of notes "in the cracks of" interval categories defined by aLbs: | ||
# Given 1 <= ''k'' <= a + b - 1, the '''neutral''' ''k''-step (abbrev. n''k''s) is an interval exactly halfway between the smaller ''k''-step and the larger ''k''-step of the mos. When the mos is generated by a (perfect) ''k''-step, this is instead called a '''semiperfect''' ''k''-step (abbrev. sP''k''ms or sP''k''s), since it is halfway between the perfect and imperfect (either diminished or augmented, depending on whether the generator is bright or dark) ''k''-step. | # Given 1 <= ''k'' <= a + b - 1, the '''neutral''' ''k''-step (abbrev. n''k''s) is an interval exactly halfway between the smaller ''k''-step and the larger ''k''-step of the mos. When the mos is generated by a (perfect) ''k''-step, this is instead called a '''semiperfect''' ''k''-step (abbrev. sP''k''ms or sP''k''s), since it is halfway between the perfect and imperfect (either diminished or augmented, depending on whether the generator is bright or dark) ''k''-step. | ||
# Given 1 <= ''k'' <= a + b − 2, and assuming that the larger ''k''-steps < the smaller (''k'' + 1)-step, the '''interordinal''' between ''k''-steps and (''k'' + 1)-steps, denoted ''k''x(''k'' + 1) or ''k''X(''k'' + 1), is the interval exactly halfway between the larger ''k''-step and the smaller (''k'' + 1)-step. The name comes from the fact that | # Given 1 <= ''k'' <= a + b − 2, and assuming that the larger ''k''-steps < the smaller (''k'' + 1)-step, the '''interordinal''' between ''k''-steps and (''k'' + 1)-steps, denoted ''k''x(''k'' + 1) or ''k''X(''k'' + 1), is the interval exactly halfway between the larger ''k''-step and the smaller (''k'' + 1)-step. The name comes from the fact that ''k''-steps in the diatonic mos are conventionally called "(''k'' + 1)ths". | ||
== The Interordinal Theorem == | == The Interordinal Theorem == | ||