A Production System for Assigning Beat Strength

What the Rules Should Represent

• Strong beats tend to be equally spaced.
• Strong beats tend not to fall on rests.
• Strong beats tend to occur on every second or third "micropulse".
• The first and last elements of a run tend to be strong.

Issues in Representing the Input

• Is processing left-to-right?
• Are the "micropulses" built into the input?
• Are elements already grouped into runs?
• How is the periodicity represented?

Input and Rules

• Input (initial Working Memory): two kinds of patterns
  • The sequence is repeated enough times so that 36 micropulses appear; each of the positions in the longer sequence is given a number.
  • To represent the sequence, there are two kinds of patterns
    • (run ?start ?finish)
    • (event ?position)
• Rules
  • Rules do two things
    • Create clauses of the form (beat ?position ?strength)
    • Modify (beat ?position ?strength) clauses by changing the ?strength
    • An example rule
      • Interpretation: Weaken any beat which is on a rest.
      • if (beat ?position ?strength)
        and (not (event ?position))
        then (beat ?position (- ?strength 1))
  • Some things we (well, I anyway) will have to worry about for this particular problem
    • The system needs to be able arithmetic on both the left- and right-hand sides
    • The system needs to have a way to update a clause of the form (beat ?position ?strength) so that the strength changes

Take me back to the Rhythm and Cognition Home Page.

Last updated: 16 November 1995
URL: http://www.indiana.edu/~gasser/rhythm_ps.html
Comments: gasser@salsa.indiana.edu
Copyright 1995, The Trustees of Indiana University