- Take two diminished chords:
C Eb F# A, andDb E G Bb. - Interlacing these, we get
C Db Eb E F# G A Bb, which is the half-tone whole tone scale. - So, if you know your diminshed chords (which you do, to play joplin and evans), then you can easily get the half-whole tone scale, which is super useful for playing over dominant chords.