Modeling Michael Jarrell’s CSP in Gelisp

Constraint Satisfaction Problems (CSPs) in computer music are used to solve harmonic, rhythmic or melodic problems. In addition,they can be used for automatic generation of musical structures satisfying a set of rules. Forinstance, the CSP proposed by compositor Michael Jarrell, which we explain in this document anddetail its implementation. Usually, a CSP is represented by a script defining the variables, theirdomain, and its constraints.Instead of writing a script, in Gelisp for OpenMusic (OM) we represent a program with a specialpatch. A patch is a visual algorithm, in which boxes represent functional calls, and connectionsare functional compositions. Inside this CSP patch, we can place special boxes: to connect eachconstraint in the CSP, to define variable and value heuristics, to define a time limit in the search,to connect the list of variables that we want to observe, and a box to connect the variable to bethe optimization criterion during the search.Furthermore, we provide a variety of boxes to represent simple constraints (e.g., a = b anda < 2) and high-level constraints (e.g., “the motive A occurs n times in the sequence S”). Theoutput of a CSP patch can be connected to three different kind of boxes: to find one solution, tofind all the solutions, and to perform propagation (narrow the domain of the variables) withoutsearch.