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wgetch | 5 years ago

Always interesting to see logic programming applied to music, it is in my experience a good fit for the musical problem space. I spent some time exploring the analysis of chords using answer set programming. On the surface ASP programs look very similar to Prolog but the semantics differ; you query Prolog to answer a question or series of questions related to your program, whereas ASP produces complete "stable models" of your program (it answers "all questions").

The first version of my analysis program would most likely have been a valid Prolog program, and furthermore the program was completely positive (contained no negation). After several weeks of rewrites, I ended up with a much smaller program that also took advantage of ASP "choice" and "optimization" rules. Much of the complexity was reduced by one fundamental improvement in the representation of internal facts and adjusting the rules to accommodate. In hindsight, the original version used a rather foolish approach, but like many things it took some effort to realize why and how to do better.

This process of rewriting and incremental improvement (and initially struggling in a less-familiar programming paradigm) gave me a great appreciation for logic systems, and also a desire to use them more often. There is something very beautiful in reducing a problem into logical relationships, and instead of focusing on algorithms just focusing on the problem space and how different pieces interrelate. It does take practice and experimentation to produce an elegant solution to a problem, but with experience it gets easier. I have no doubt the author of this article could make it feasible to discover chords and tunings as he describes in the Future Work section. Though I would recommend starting over with this goal in mind; even a naive but viable solution might reveal some property of the system that would transfer over to the original program and increase its versatility.

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