Let’s look at a typical progression and see what relationships we have between the chords.
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This progression can be analyzed with jazz/pop chord symbols and roman numerals as shown below:
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The relationship between each two chords can also be analyzed as an NRT transformation.
Chords 1-2 (F to D-): Relative relationship (R) since F major and D minor are relative major and minor keys.
Chords 2-3 (D- to Bb): Leading tone relationship (L) since D- and Bb major have 2 notes in common and the other notes are a half step away.
Chords 3-4 (Bb to Bb-): Parallel relationship (P) since Bb major and Bb minor are parallel major and minor chords/keys.
Chords 4-5 (Bb- to Gb): Leading tone relationship (L) since Bb- and Gb major have 2 notes in common and the other notes are a half step away.
These relationships can be seen below:
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These relationships can be seen on the tonnetz as follows:
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