3-1

One shape, its own mirror

Interval content

Every set in the class holds two semitones, one whole tone, no minor thirds, no major thirds, no fourths and no tritones.

Common tones

Notes a set keeps when transposed by n.

Notes a set keeps when inverted about n.

Its 12 sets

Set theory treats D# and Eb as one pitch class; the names under each set use one fixed spelling, sharps except Bb.

012

• 012C C# D
• 123C# D D#
• 234D D# E
• 345D# E F
• 456E F F#
• 567F F# G
• 678F# G G#
• 789G G# A
• 89tG# A Bb
• 9teA Bb B
• 0teBb B C
• 01eB C C#

Relations

Complement

9-1 012345678

Z-partner

none: no other class has this interval vector

Symmetry

T0 and one inversion map it onto itself

Inside it

2 notes: 2-1 ×2 · 2-2

Around it

4-1 ×2 · 4-2 ×2 · 4-4 ×2 · 4-5 ×2 · 4-6 · and 130 larger classes