Interval arithmetic

Interval arithmetic systems refer to sets of rules regarding the names and qualities of stacked intervals.

Diatonic interval arithmetic

Diatonic interval arithmetic is a set of rules governing diatonic notation systems, which says that the degrees of stacked intervals should always follow arithmetic if 1 is subtracted from all degree numbers. For example, a stack of two thirds is always a fifth, since (3-1)+(3-1)=(5-1).