MOS substitution: Difference between revisions

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In other words, there exist non-negative integers ''m'', ''n'', 0 < ''a'' < ''n'', 0 < ''b'' < ''n'', a vector '''a''', and two linearly independent vectors '''v''' and '''w''' such that the set of notes in the scale as a subset of the pitch-class lattice is

<math>\{\mathbf{a} + i\mathbf{v}\}_{i=a}^{n-1} \cup \{\mathbf{a} + i\mathbf{v} + j\mathbf{w}\}_{(i,j) \in [n]_0 \times [m-1]_1} \cup \{\mathbf{a} + i\mathbf{v} + m\mathbf{w}\}_{i=0}^{b}.</math>

<math>\{\mathbf{a} + i\mathbf{v}\}_{i=a}^{n-1} \cup \{\mathbf{a} + i\mathbf{v} + j\mathbf{w}\}_{(i,j) \in [n]_0 \times [m-2]_1} \cup \{\mathbf{a} + i\mathbf{v} + m\mathbf{w}\}_{i=0}^{b}.</math>

Let us call rank-3 scales with such lattice shapes ''almost parallelograms''. MOS substitution scales are thus almost parallelograms, but the converse is false, as the scale in 5 letters [9/8 28/27 9/8 64/63 9/8 28/27 243/224 28/27 64/63 567/512 64/63] is almost a parallelogram.

@@ Line 135: / Line 135: @@
 In other words, there exist non-negative integers ''m'', ''n'', 0 < ''a'' < ''n'', 0 < ''b'' < ''n'', a vector '''a''', and two linearly independent vectors '''v''' and '''w''' such that the set of notes in the scale as a subset of the pitch-class lattice is
-<math>\{\mathbf{a} + i\mathbf{v}\}_{i=a}^{n-1} \cup \{\mathbf{a}  + i\mathbf{v} + j\mathbf{w}\}_{(i,j) \in [n]_0 \times [m-1]_1} \cup \{\mathbf{a} + i\mathbf{v} + m\mathbf{w}\}_{i=0}^{b}.</math>
+<math>\{\mathbf{a} + i\mathbf{v}\}_{i=a}^{n-1} \cup \{\mathbf{a}  + i\mathbf{v} + j\mathbf{w}\}_{(i,j) \in [n]_0 \times [m-2]_1} \cup \{\mathbf{a} + i\mathbf{v} + m\mathbf{w}\}_{i=0}^{b}.</math>
 Let us call rank-3 scales with such lattice shapes ''almost parallelograms''. MOS substitution scales are thus almost parallelograms, but the converse is false, as the scale in 5 letters [9/8 28/27 9/8 64/63 9/8 28/27 243/224 28/27 64/63 567/512 64/63] is almost a parallelogram.