To mark the 250th anniversary of Beethoven's birth, Deutsche Telekom commissioned a team to develop with machine learning Beethoven's fragmentary sketches for a Tenth symphony. Here, the research part of that team discuss some of the key musical and computational decisions involved, including: making sense of Beethoven's few, ambiguous plans for this work; curating that and other musical data in machine-readable formats; and identifying suitable generation tasks, relevant training materials, and network architectures. Most of all, we consider highly topical themes for AI in the creative arts today, notably on the interaction between not only human and computer, but also living and historical artists.