Computing ‘ideas’ - Bol Processor

Dwaram Venkataswamy Naidu playing a violin (credit)

A composition in Carnatic musical style by Srikumar K. Subramanian, June 1995.
Name: "-gr.trial.mohanam"

This is a non-stop improvisation of variations in a style similar to Carnatic music. The compositional approach here is to decide that each variation should contain 32 notes and can use up to 20 "ideas". To do this, a flag called Ideas is set to 20 at the beginning, and it is decreased by 1 unit in certain rules (such as GRAM#2[2]) or 2 units in others (such as GRAM#2[3]). See the page Flags in grammars for more details.

Rules in subgrammar #3 can only be candidates if there are few ideas left, but they do not reduce ideas.

Rules in subgrammar #6 use wildcards to create patterns.

Rules in subgrammar #9 create "effects" by changing velocities.

ORD
GRAM#1[1] S --> _transpose(-5) I /Ideas=20/ /Notes=32/ /NumR=1/

RND
GRAM#2[1] <0> I --> I /NumR+1/ [This rule is only fired on a _goto()]
GRAM#2[2] <20> /Ideas-1/ I --> R1 A R2
GRAM#2[3] <50> /Ideas-2/ I --> A B
GRAM#2[4] <20> /Ideas-1/ I --> R1 B R2
GRAM#2[5] <50> /Ideas-2/ I --> B A

RND
GRAM#3[1] <100> /Ideas/ /NumR-1/ A --> I
GRAM#3[2] <100> /Ideas/ /NumR-1/ B --> I
GRAM#3[3] <1> /Ideas/ I --> I _goto(2,1)

SUB1
GRAM#4[1] I --> lambda

RND
GRAM#5[1] <50-12> /Notes-4/ A --> P4
GRAM#5[2] <50-9> /Notes-3/ A --> P3
GRAM#5[3] <50-10> /Notes-2/ A --> P2
GRAM#5[4] <50-12> /Notes-4/ B --> Q4
GRAM#5[5] <50-9> /Notes-3/ B --> Q3
GRAM#5[6] <50-10> /Notes-2/ B --> Q2

RND
GRAM#6[1] R1 ?1 R2 --> ?1 ?1
GRAM#6[2] R1 ?1 ?2 R2 --> ?1 ?2 ?1 ?2
GRAM#6[3] R1 ?1 ?2 ?3 R2 --> ?1 ?2 ?3 ?1 ?2 ?3
GRAM#6[4] R1 ?1 ?2 ?3 ?4 R2 --> ?1 ?2 ?3 ?4 ?1 ?2 ?3 ?4
GRAM#6[5] R1 ?1 ?2 ?3 ?4 ?5 R2 --> ?1 ?2 ?3 ?4 ?5 ?1 ?2 ?3 ?4 ?5

RND
GRAM#7[1] P4 --> P41
GRAM#7[2] P4 --> P42
GRAM#7[3] P4 --> P43
GRAM#7[4] P4 --> P44
GRAM#7[5] P3 --> P31
GRAM#7[6] P3 --> P32
GRAM#7[7] P2 --> P21
GRAM#7[8] P2 --> P22
GRAM#7[9] Q4 --> Q41
GRAM#7[10] Q4 --> Q42
GRAM#7[11] Q4 --> Q43
GRAM#7[12] Q4 --> Q44
GRAM#7[13] Q3 --> Q31
GRAM#7[14] Q3 --> Q32
GRAM#7[15] Q3 --> Q33
GRAM#7[16] Q3 --> Q34
GRAM#7[17] Q2 --> Q21
GRAM#7[18] Q2 --> Q22
GRAM#7[19] Q2 --> Q23

RND
GRAM#8[1] R1 --> lambda
GRAM#8[2] R2 --> lambda

RND [Effects]
GRAM#9[1] Str ?1 --> _vel(110) ?1 _vel(64)
GRAM#9[2] Step3Up ?1 ?2 ?3 --> _vel(80) ?1 _vel(95) ?2 _vel(110) ?3 _vel(64)
GRAM#9[3] Step3Dn ?1 ?2 ?3 --> _vel(110) ?1 _vel(95) ?2 _vel(80) ?3 _vel(64)
GRAM#9[4] P41 --> sa6 re6 ga6 pa6
GRAM#9[5] P42 --> re6 ga6 pa6 ga6
GRAM#9[7] P43 --> dha6 pa6 ga6 pa6
GRAM#9[9] P44 --> ga6 Str dha6 pa6 Str dha6
GRAM#9[11] P31 --> ga6 pa6 dha6
GRAM#9[13] P32 --> sa6 ga6 re6
GRAM#9[14] P33 --> Str ga6 re6 sa6
GRAM#9[15] P34 --> Str sa7 dha6 pa6
GRAM#9[17] P21 --> ga6 pa6
GRAM#9[19] P22 --> sa6 Str ga6
GRAM#9[20] Q41 --> Str ga6 _ re6 sa6
GRAM#9[22] Q42 --> Str re6 ga6 _ re6
GRAM#9[24] Q43 --> ga6 _ pa6 Str dha6
GRAM#9[26] Q44 --> Str sa6 re6 _ ga6
GRAM#9[28] Q31 --> sa6 _ re6
GRAM#9[29] Q32 --> sa6 _ ga6
GRAM#9[30] Q33 --> Str sa7 dha6
GRAM#9[32] Q34 --> ga6 _ _
GRAM#9[34] Q21 --> ga6 ga6
GRAM#9[36] Q22 --> pa6 pa6
GRAM#9[38] Q23 --> Str dha6 Str dha6

In the ‘Improvize’ mode, the values of flags and rule weights can be carried over from one variation to the next. This allows them to be used to trigger/inhibit events at any distance from those that created/modified them.

The following output was recorded on a Roland D-50 synthesiser.

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