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b. (Dynamics) the transition n2-n3 involves a change in dynamics
and n1-n2 and n3-n4 do not, or if
c. (Articulation) the transition n2-n3 involves a change in articulation
and n1-n2 and n3-n4 do not, or if
d. (Length) n2 and n3 are of different lenghts and both pairs n1,n2
and n3,n4 do not differ in lenght.
GPR 4 (Intensification)
Where the effects picked out by GPRs 2 and 3 are relatively more pronounced,
a larger-level group boundary may be placed.
GPR 5 (Symmetry)
Prefer grouping analyses that most closely approach
the ideal subdivision of groups into twoparts of equal
length.
GPR 6 (Parallelism)
Where two or more segments of the music can be
construed as parallel, they preferably form parallel
parts of groups.
GPR 7 (Time-Span and Prolongational Stability)
Prefer a grouping structure that results in more stable
time-span and/or prolongational reductions.
Grouping Overlap
Given a well-formed underlying grouping structure G
as described by GWFRs 1-5, containing two adjacent
groups g1 and g2 such that
g1 ends with event e1,
g2 begins with event e2, and
e1 = e2,
a well-formed surface grouping structure G' may be
formed that is identical to G except that
it contains one event e1 where G had the sequence
e1e2,
e' = e1 = e2,
all groups ending with e1 in G end with e' in G', and
all groups beginning with e2 in G begin with e' in G'.
Grouping Elision
Given a well-formed underlying grouping structure G
as described by GWFRs 1-5, containing two adjacent
groups g1 and g2 such that
g1 ends with event e1,
g2 begins with event e2, and
(for left elision) e1 is harmonically identical to e2
and less than e2 in dynamics and pitch range or
(for right elision) e2 is harmonically identical to e1
and less than e1 in dynamics and pitch range,
a well-formed surface grouping structure G' may be
formed that is identical to G except that
it contains one event e1 where G had the sequence
e1e2, |