Ternary scale theorems: Difference between revisions
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# If ''n'' is odd, ''s'' is of the form ''a'''''x''' ''b'''''y''' ''b'''''z''' for some permutation {{nowrap|('''x''', '''y''', '''z''')}} of {{nowrap|('''L''', '''M''', '''s''')}}. | # If ''n'' is odd, ''s'' is of the form ''a'''''x''' ''b'''''y''' ''b'''''z''' for some permutation {{nowrap|('''x''', '''y''', '''z''')}} of {{nowrap|('''L''', '''M''', '''s''')}}. | ||
# If ''n'' is odd, ''s'' is abstractly SV3 (i.e. SV3 for almost all tunings). | # If ''n'' is odd, ''s'' is abstractly SV3 (i.e. SV3 for almost all tunings). | ||
# If ''n'' is odd, then the result of identifying the two equinumerous step sizes is a primitive MOS. | |||
# If ''n'' is odd, {{nowrap|''s'' {{=}} ''a'''''X''' ''b'''''Y''' ''b'''''Z'''}} is obtained from some mode of the (primitive) MOS ''a'''''X''' 2''b'''''W''' by replacing all the '''W'''s successively with alternating '''Y'''s and '''Z'''s (or alternating '''Z'''s and '''Y'''s for the other chirality, fixing the mode of ''a'''''X''' 2''b'''''W'''). The two alternants differ by replacing one '''Y''' with a '''Z'''. In other words, ''s'' is ''odd-regular'' in our classification of MV3 scales. | # If ''n'' is odd, {{nowrap|''s'' {{=}} ''a'''''X''' ''b'''''Y''' ''b'''''Z'''}} is obtained from some mode of the (primitive) MOS ''a'''''X''' 2''b'''''W''' by replacing all the '''W'''s successively with alternating '''Y'''s and '''Z'''s (or alternating '''Z'''s and '''Y'''s for the other chirality, fixing the mode of ''a'''''X''' 2''b'''''W'''). The two alternants differ by replacing one '''Y''' with a '''Z'''. In other words, ''s'' is ''odd-regular'' in our classification of MV3 scales. | ||
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==== Statement (4) ==== | ==== Statement (4) ==== | ||
==== Statement (5) ==== | |||
By part (2), we have that ''s'' has step signature {{nowrap|''a'''''X''' ''b'''''Y''' ''b'''''Z'''}}, ''a'' odd. By part (4), we have that {{nowrap|''T''('''X''', '''W''') {{=}} ''s''('''X''', '''W''', '''W''')}} is a MOS scale ''a'''''X'''2''b'''''W'''. If {{nowrap|''b'' {{=}} 1}}, there's nothing to prove, so assume {{nowrap|''b'' > 1}}. | By part (2), we have that ''s'' has step signature {{nowrap|''a'''''X''' ''b'''''Y''' ''b'''''Z'''}}, ''a'' odd. By part (4), we have that {{nowrap|''T''('''X''', '''W''') {{=}} ''s''('''X''', '''W''', '''W''')}} is a MOS scale ''a'''''X'''2''b'''''W'''. If {{nowrap|''b'' {{=}} 1}}, there's nothing to prove, so assume {{nowrap|''b'' > 1}}. | ||