Generic and specific intervals: Difference between revisions

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[[Image:Maximal evenness seconds.png|thumb|The [[major scale]] is [[maximal evenness|maximally even]]. For example, for every generic interval of a second there are only two possible specific intervals: 1 semitone (a minor second) or 2 semitones (a major second).]]
 
In [[diatonic set theory]], a '''generic interval''' is the number of scale [[Step (music)|steps]] between [[note (music)|notes]] of a [[Set (music)|collection]] or [[scale (music)|scale]]. The largest generic [[interval (music)|interval]] is one less than the number of scale members. (Johnson 2003, p. 26)
 
A '''specific interval''' is the clockwise distance between [[pitch class]]es on the [[chromatic circle]] ([[interval class]]), in other words the number of [[half step]]s between [[note (music)|notes]]. The largest specific [[interval (music)|interval]] is one less than the number of "chromatic" pitches. In twelve tone equal temperament the largest specific interval is 11. (Johnson 2003, p. 26)
 
In the [[diatonic collection]] the generic interval is one less than the corresponding diatonic interval:
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==Myhill's property<!--'Myhill's property' redirects here-->==
'''Myhill's property'''<!--boldface per WP:R#PLA--> is the quality of [[musical scale]]s or collections with exactly two specific intervals for every generic interval, and thus also have the properties of [[cardinality equals variety]], [[structure implies multiplicity]], and being a [[well formed generated collection|well-formed generated collection]]. In other words, each generic interval can be made from one of two possible different specific intervals. For example, there are major or minor and perfect or augmented/diminished variants of all the diatonic intervals:
 
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