Computer Models of Musical Creativity (David Cope)
Chapter 4: Recombinance

  • Western tonal music generally follows simple principles that drive melody, harmony, voice leading, and hierarchical form
  • One can create music by programming such principles into a computer
  • Such an approach often creates stale music
  • Recombinance is a method of using existing music and recombining it logically to create new music
  • Cope uses destination pitches and beat-size groupings to split chorales into smaller groups called lexicons that can be recombined using the pitch and beat data
  • Such syntactic networking actually preserves a great deal of the music's integrity while generating new output
  • To further extend the abilities of recombinance, Cope had his program analyze the source piece's "distance to cadence, position of groupings in relation to meter, and other context-sensitive features"
  • Artists often use musical signatures, patterns of notes that recur in many works of a composer
  • Recombinance can be described in terms of Markov chains
  • Recombinance can work both vertically and horizontally
  • Generation of music must start with an abstract hierarchy and move towards specifics (this is exactly what I foresaw and intended when I made the structure module the foundation upon which mGen works! Cope agrees!)
  • Rule acquisition from music models the musical training of humans
  • Machine renditions of music are often crude and dead...successful algorithmic composition requires dynamics
  • An improviser basically has a repertory and an idea of how he or she wants an improvised idea to flow into the next
  • "Recombinance, or rules acquisition, provides more logical and successful approaches to composing in tonal music styles"
  • "Every work of music, I feel, contains a set of instructions for creating different but highly related replications of itself"
  • "The secret of successful creativity lies not in the invention of new alphabet letters or musical pitches, but in the elegance of the combination and recombination of existing letters and pitches"
  • "In recombination, rules are not necessary, since the destination notes provide all of the requisite information"
  • "While recombinance of this type ensures beat-to-beat logic in new compositions, it does not guarantee the same logic at higher levels"
  • "The initial and final groupings of a phrase are most pivotal"
  • "Experiments in Musical Intelligence protects signatures from being fragmented into smaller groupings, thus ensuring that these signatures will survive the recombination process"
  • "A Markovian description of recombinant processes does not allow for the broader control of larger-scale structure"
  • "In music, what happens in measure 5 may directly influence what happens in measure 55, without necessarily affecting any of the intervening measures"
  • "The top-down approach is necessary because choosing new beat-to-beat groupings must be informed by hierarchy, and not the reverse. No new grouping of a work-in-progress can be selected until its implications for the entire structure of the work are determined"
  • "Acquired rules are often more accurate since, by default, they originate from the music itself and not from generalizations about the music"
  • "Having a program first derive rules and then apply these rules during composition, though a simple notion, is critically important to the basic thrust of my modeling creativity"
  • "I continue to maintain that computer-composed music in any style is as real as human-composed music in any style"
  • "I see no reason why computer-created music cannot move us to tears, find roots in our cultures, and reveal or obscure its internal implications as much as any music composed in more traditional ways"
  • "Improvisation consists of either generating music associatively to maintain continuity, or interruptively striking out in apparently new directions"
  • "Improvisers associate rhythmic patterns, melodic contours, and harmony"
  • "Improvisation tends to function as a series of gestures that themselves have a sense of beat and that, when performed one after another, make musical, rhythmic, and metric sense"