Mozart's musical dice game

You may not like the so-called Turkish music improvised on a so-called Koto... I would recommend listening to the marvellous CD "Masters of Turkish Music" (Rounder CD 1051) and apologise to Turkish music lovers and lovely Koto players for such a joke.

How about some unknown pieces (presumably) composed by Wolfgang Amadeus Mozart? Select "Load project" in the "File" menu (cmd-l) and load

This grammar uses "simple notes", i.e. the predefined alphabet of French notes. This convention has been automatically selected when settings "-se.Mozart" were loaded.

Now produce items (cmd-r)...

In the current set-up (mm = 220 ticks/min) the duration of any variation is about 26 seconds, slightly more than computation time on a Mac II-ci. Therefore, Mac II-ci and faster machines are able to string variations without break. You may also save time by unchecking "Show messages" in the "Settings" dialog.

Weights of some rules in the grammar are controlled by <K1>, <K2>, etc., and may be changed by MIDI controllers (see §6.5). Since controllers are not used here, these parameters are assigned the constant values defined in the first grammar. These actually reflect the probabilities of getting 2, 3, 4,..., 12, out of a two-dice throw. An explanation of weights may be found in the reference manual, §4.6.

The last subgrammar has instruction "SUB1", a faster version of "SUB" when substitutions are to be performed only once.

You may select polymetric expressions in the last subgrammar and play them (cmd-p) in order to listen to the various units defined by the composer. If the selection contains a variable it is used as a start string by the grammar. Try for instance to play "A1 A2 A3".

To select an expression with balanced curled brackets {}, click anywhere inside the expression and type cmd-b ('balance'). Repeat typing to extend the selection.

How was this grammar created? Subgrammars 1 to 17 have been directly typed from Mozart's tables. Subgrammar 18 contains the "terminals" of the "dice grammar": musical segments taken from Mozart's score in conventional music notation. Selecting "Type from MIDI" in the "Misc" menu, or typing cmd-j allowed BP2 to capture notes from a MIDI keyboard, and prolongations '_' with the "hold" pedal.

If you are not yet familiar with polymetric structures, this grammar can teach you the essential: select structures, play them and compare polymetric expressions with their "scores" appearing on the "Graphic" window.