The Algorithmic Composer (review)

David Cope: The Algorithmic Composer. Softcover, 2000, ISBN 0-89579-454-3, 302 pages, illustrated, bibliography, index, comprehensive index (to CMDAU, Volumes 6, 12, 16), CD-ROM; A-R Editions, Computer Music and Digital Audio Series, Volume 16; A-R Editions, Inc., 801 Deming Way, Madison, Wisconsin 53717-1903, USA; telephone (800) 736-0070 or (608) 836-9000; fax (608) 831-8200; electronic mail info@areditions.com; World Wide Web www.areditions.com

David Cope's newest book, The Algorithmic Composer, is the third installment of a trilogy, of which Computers and Musical Style (1991) and Experiments in Musical Intelligence (1996) comprise the first two volumes. (These two books have also spun off three commercially available compact discs on the Centaur label: Bach by Design, Classical Music Composed by Computer, and Virtual Mozart.) All three volumes share the following compelling premise: "Every work of music contains a set of instructions for creating different but highly related replications of itself. These instructions, interpreted correctly, can lead to important discoveries about structure and possibly style." The first two books describe in detail Mr. Cope's method both for extracting these instructions into a database and for putting the instructions to use in the creation of novel works which are arguably in the style of the music contained in the database.

Whereas the objective of the first two books is the use of "recombinancy" to create entire compositions in the style of the works in the database (by Mozart, Bach, Joplin, etc.), The Algorithmic Composer has a somewhat different orientation. The software program described within--ALICE (ALgorithmically Integrated Composing Environment)--is intended to function as a collaborative, interactive creative assistant, rather than as an independent virtual composer. The emphasis is thus on the augmentation and extension of user-composed music rather than on the creation of completed works. Mr. Cope envisions a working environment in which a composer, moments after creating a phrase of music, could request ALICE to spin out several stylistically consistent variations and transformations, which the composer could then consider as possibilities for inclusion in the work at hand. ALICE would also grow in "understanding" as the work proceeds, giving progressively more honed responses. As the importance of the current book lies equally with the quality of the software that is described within as with the prose contained in the book, the following offers both an overview of the program as well as reflections on the text.

The success or failure of ALICE's output critically depends upon the quality of the database with which it works. The pieces of music in the database must all be massaged into a similar format--they should resemble one another with respect to meter, tempo, and so forth (this is to facilitate pattern-matching). The process by which databases are created is more or less the same with ALICE as it is with Mr. Cope's Experiments in Musical Intelligence (EMI) program, and the author refers the reader to the second volume of the series for more information on this important process.

Once a robust database has been created, ALICE is ready to begin deriving rules from the music, rules which attempt to "extrapolate basic principles from examples." This extraction of rules makes several powerful operations available. The user can view the rules from a given musical database and compare them to rules derived from another database, which may yield potentially important insights. Also, users can change the rules directly, taking, say, rules for pitches from one database and rules for rhythms from another. These types of transformations are all possible because ALICE works not with actual musical data, but with principles derived from the data.

One of the primary issues involved in analyzing the database is the determination of "grouping size," that is, how to segment the music into meaningful chunks. When the sizes are too small, the results will be too random sounding, and when they are too large, too much of the source material will come through unchanged. ALICE addresses...